Great info Steve but you do realise that it's just not going to happen. Rightly or wrongly your average builder is not going to take that must care over the detailing and building control certainly don't pay much attention to it. Constantly changing regulations and standards just add to the problems. We are having to price for ever increasing insulation requirements and still remain competitive AND keep our guys employed AND make a decent living for ourselves. Try telling a customer that your quote is more expensive because you have got to seal the AVCL with the special (ie expensive) butyl tape, oh and yes we cant use the same PIR that we've always been able to use for years, we now need to use this special (ie more expensive, and no doubt unobtainable from my normal supplier) PIR. I'm just glad that i'm old enough to retire soon and leave all this behind me.
IF the specification is given to a builder / roofer they have to do the work correctly or will be held responsible. Hidden costs in materials and labour are horrendous when you look at the correct way of doing this. Easily missed when tendering. Because you cannot see this once the job has been finished it's never installed correctly this can cause problems and huge costs at a later date. There are other ways of doing this and I will be going into those in other videos shortly.
@@doreenbritton5828 It's very unlikely you will, if you can even find one other example on TH-cam etc of a roofer/builder going to these lengths I'd be amazed to say the least. This is the gold standard... but to be fair most customers probably wouldn't want or couldn't pay the extra for this.
Some good information in your videos! A new sub from me. Looks like we will all be living in polythene bags! warm but no fresh air in? Where is all the moisture going to go created in the home? When everyone shuts up for winter unless you have ventilation you’re going to be breathing in stale air? Would be nice to go into one of these sealed homes and see what the co2 levels are with a home not breathing! or do they have heat recovery air in/out vent fans. This could all be done to aid killing you off earlier with poor air quality. Only my thoughts I live in a costal old town and the buildings are cold but they breathe and have lasted 100s of years some simple upgrades have halved the heating costs, upgrading loft insulation and cellotex on the inside of the external walls, obviously double glazing would help but not permitted in conservation areas.
Without a MVHR these super insulated homes run dangerous levels of CO2. I did a little experiment in our place, in the kitchen (super insulated) with 5 of us in there for lunch the CO2 goes from 420-1100ppm (no MVHR). That is not going to kill us but its not good for working in - just feel very sleepy. I've built a number of places with MVHR units and it is a revelation, its like being outside in the most fresh day but with the warmth you'd expect inside and no wind. They are quiet and can be set to kick in/ up a gear on higher CO2 / occupancy. It's like everything though, if the house is properly insulated as per this video with MVHR it's going to be amazing...but cut a few corners or lots of them (as many builders do) and the will catch up and bit the homeowner hard, especially if the person who has to make the repair doesn't understand what's really happened and we have such a shortage of builders who really understand the mechanics of this.
This whole vapour barrier thing is a nightmare because it has to be broken for most lighting and fixings etc sockets. For a cold roof if the 50mm void above the insulation is continuous from vented soffit to soffit in a garden room a few holes in the VB won’t hurt too much as you are getting that moisture straight out of the roof space? Best thing we could all live in is a open barn no condensation problems then ha. Keep up the amazing work
That's why in Norway it is standard to have the plastic layer then stud it out with a 2x2 the other way and now we have a service cavity for electric and water without needing to make any holes in the vapor barrier
Another great video! Wasn't sure what you meant by air vapour control layer in the other video, so this explained it beautifully. Will have to look into it after I finish the initial work I'm doing.
Hi Steve, nice to find you on here! I'm always watching building videos, trying to learn something new. Looked for a video on vapour barriers and thought "Hey I know that fella!" Hope you're keeping well 👍
Your videos are so spot on 👍…. The question I have is …. Can you use black DPM as a vapour Barrier??? … on walls or ceilings . The research I have seen is full of so much conflicting advice . So I thought I would ask the main man !! Your advice will be gold All the best Pete 👍
I had the need to use a thermal imaging camera once. When digging deeper, I found out about surface emissivity. If you look into that you will realise that a thermal imaging camera does not magically measure the surface temperature, all it does is measure the intensity of the infrared radiation emitted. Different surfaces have different emissivity's, so for the same temperature, they emit different amounts of infrared radiation, so the temperature measurement is really an approximation, but can be used for comparative purposes when done on the same surface material.
Ridiculous overkill. Most are low occupancy garden rooms , no steam from kettles , shower rooms , kitchens etc . I’m convinced that these big businesses selling these products are brain washing people into buying all these products unnecessarily. I built a garden room 25 yrs ago with none of these products, granted it’s not as well insulated as I would like , but it’s still stood and I’ve never had a problem with damp or moisture. Walls are 3/4” ply , 4” fibreglass insulation, plasterboard and skimmed , never had a spot of moisture or damp damage and it used to house a spa tub.
This is for ALL constructions that involve timber frame or SFS (light steel frame) type builds. This is not just a home office / garden building way of constructing things. Passive house building is a good example where this sort of methodology is used, but very common in modern construction types, both domestic housing and light commercial.
For context Steve works in South London where in many areas that a house without a loft conversion (read timber room built like this) is the odd one out. All new builds will have a habitat room in the roof down south. This is very relevant to house building, extensions and the roof, he is just standing in a test rig at ground level.
@@loneturk3y for new builds that are energy efficient that means all new extensions loft conversions and new houses and flats we have to be really careful with how we control the internal environment and this may mean adding an air vapour control layer. Sometimes the house may be designed to be breathable in which case a vapour control layer may not be needed or can be of lower quality.
I can’t imagine this being a good idea in an old house. The guys working on stone built houses without damp courses stress the benefits of the wall being able to breath, so controlling the water in the wall
Fair enough doing everything to the highest standard but I don't buy into the idea of issues without taking things to this level. I have a cold roof garden office and loft. No vapour barrier in the loft (before I knew as much as I do now), PIR insulation with a good air gap behind. Down lights cut out. No issues. Office I did to the best of my knowledge at the time. Warm roof was not possible due to height restrictions and converting an already brick building. Internal brick was painted with black jack. As it was bone dry when I purchased the house I decided to do a new coat of black jack, air vents either side of the roof, left a big 50mm air gap on top including cross ventilation (furrings), PIR insulation between joists on ceiling, downlights cut out with no big attempt to seal, used cavity insulation for walls, used a green vapour control layer all over, left big overlaps and used the cheapo silver tape for joints. Probably used more screws than needed for plasterboard. No issues.
If you paid a professional person to do the job and they didn't do it correctly and it went wrong who would you turn to to put it right? So professional people should do it correctly otherwise they could have some large claims against them
Once a building is airtight sealed in this way, how do you let moisture out? Especially in a bathroom or kitchen. I will be building an extension in Sept with both these rooms, and would like to get it right. Apologies if this something covered in your videos, thanks
on a standard loft conversion, there is a sloping roof to the front and a flat roof over the center and rear dorm. How do you do a warm roof? it will be hard to do a warm roof on the sloping part so how can you join a cold roof to a warm roof, or am i asking the wrong question, should I be asking how to do a warm roof over the sloping part.
On the rig that I'm working on I will do a video regarding that however to answer your question you do a cold roof over the pitch area and a warm roof over the flat area.
Hi great video thanks. How do you deal with lightning cables and downlights when having to use 150mm celeotex between the rafters and then 50mm celeotex below that, ie vapour barrier when having downlights and also having to deal with restricted height
Thanks for the info Steve. I’ve got a 200yo stone cottage on the outskirts of Glasgow and I’m just about to start insulating myself… Is it necessary to insulate walls that aren’t a part of the exterior wall, separating walls if you like? I’ve decided to use ROCKWOOL for its various properties, one being that rodents don’t like to live in it, and we definitely have mice. I’ve also ordered the Novia green barrier, silver foil tape and butyl tape from Novia too. Thanks in advance 😊👍
Steve will you do another thermal camera scan now it's got an air tight layer. I remember some warm spots due to air migration, have these been reduced now air movement is controlled?
Hi Steve, With walls and ceilings sealed like this, putting any fixtures to the walls/ceiling is basically a nono? Eg wall plugs, TV brackets, shelving support etc. Everything which require some type of piercing through the plasterboard will likely puncture the vcl. Basically you are saying, insulation layer of 150mm + gap/space, plus 75mm all round framing to accommodate any fixings...
Great videos Steve. I wonder if you could help with one question. On a timber frame garden room, with a warm flat roof. I’m struggling to think of a way of forming an air tight VCL seal, in between the roof joists, where they sit over the stud walls. Would it be a problem to add an additional VCL on the underside of the joists like on a cold roof, and tape to the wall VCL, or would this cause an issue with an additional layer, as there is already a VCL under the insulation on the warm roof. Thanks in advance.
Hi Steve. Thanks for sharing, I am doing a conservatory with a flat cold roof, I have used 6x2 timbers at 2.5m long, then used 6x2 cut down to foam my slope so it is raised 6" over 6ft, I will be inserting vents into the soft to allow air flow through, internal I will do the vapour barrier at 130 as in your video,👍 My question is the breeze block and how would I seal the vapour barrier to these🤔 Thanks Sean
What would be your opinion about where or if any vapour control layer/barrier in a suspended timber frame ground floor, new build, access underneath via crawlspace , with pir insulation in-between joist. I am thinking from bottom up , breathable roofing membrane , joist with pir insulation between insulation to top of joist providing air space beneath below to membrane, next is where I'm lost, is it osb board then vapour and some foam over to protect from Finnish laminate flooring or , vapour barrier then osb board or and vapour lol thanks ,great videos and information in all your roofing details
I think I replied to this earlier just make sure it's well sealed with the vapour barrier the vapour barrier extends to the height of the insulation and perhaps insulate hire around the pipe to stop thermal bridging
I have a room that is in part below an open air Deck access (walkway). The ceiling is concrete slab. From watching your videos I must create a warm roof as to insulate internal there would be no air flow between the concrete slab and insulation? This correct thinkingness on this matter?
A good followup video after this one would be one showing the damage a cold roof can get after installing PIR plates taped only with silver tape (the regular one, not that strong stuff). I was assisting last week a company that only used PIR plates and pur foam to close the gabs and some silver tape. Where the PIR met a stone wall they put the silver tape decoratively over the pur foam but not on the wall because that would let go. No Air Vapour Control Layer was added. The customer of course was very happy, but what does she know? If there will be damage because of wood rot, years after, will he/she be able to put that liability to the installation company? I find this all very disturbing.
Great demo. Is MVHR essential if you seal a room/house to this standard? What is the new style insulation your mentioned in a previous vid. Moving away from PIR?
Hi Steve, Would really appreciate your opinion if you had a minute, Would this Vapour barrier spec be suitable for a standard cold roof in a medium occupancy garden room: Semi transparent green visqueen. AVCL SD - 128 MNs/g - 633 Permeability - 0.21 Thickness 0.3 mm No excessive mouisture being produced, RH being kept around 50%. All airtight details and correct tapes used. Many thanks if you have time to respond.
I’m having the kitchen plastered which has a cold roof. I’ll be fitting the vapour barrier to the ceiling but where it meets the top of the wall, can this be taped down then plastered over? Thanks
New building regs are now suggesting that we all use this new type code Gatotape expensive to buy expensive to install and the only thing on the market at the moment
Need some advice Steve I have been told you can't fibreglass over OSB board coated with bitumen paint as it won't stick so if you cover with 3mm hardboard will that be ok to fibreglass over thanks, your help will be much appreciated
It's not so much that it doesn't stick it reacts with the tar so all you need to do is put a barrier between the two and you're good to go 3 mm hardboard you could do but why are use glass fibre because it is a very bad roofing material use something more flexible
Hi Steve great videos I’ve watched so many, can I ask a question? I’m doing a cold roof on my new wooden workshop because of height restrictions, I’m happy with that process. However looking online I’m really struggling to see whether there needs to be a air gap for ventilation in my walls as well, like the cold roof needs? From the outside in, the walls will be 45mm tongue and groove, 100mm cavity slabs, vapour barrier, then some sort of inside wall like OSB, thick enough that I can screw into without reaching the vapour barrier. So do any of those layers need an air gap? Many thanks I hope you get the time to reply! :)
Wall design is different to roof design as there is normally less present on them. A vented rain screen ie outer layer is always recommended but seldom done
@@SteveRoofer thank you that’s sort of what I thought, in a roof it’s so critical because of heat rising and gravity causing condensation to sit. But in the walls I should be ok, especially as my 100mm rock wall slabs are breathable? It’s to late to add a breathable membrane unfortunately I’m too far into the build
New building regulations come out this week and we think the new regulations will mean that on a retrofit roof the thickness of insulation to get to the correct U value will be 150 mm it used to be 120 mm
I’m in the process of doing garage conversion, the more I watch your videos the more dismayed I get, I have a cold roof so I have to create a false sealing due to ventilation for building regs, getting into vapour barriers etc it now seems down lighters will affect that, it’s a bloody mind field and a costly one, how the hell do you put sockets in and wires through if it’s going through the vapour barrier, by the time I’m done the head height will be about 4 foot!
Hi, great content. I'm learning loads. Quick question. On a warm flat roof,Should I put a vapor control under the ceiling joist aswell as the one under the insulation? Thanks
Hi Steve, what's your experience of multifoil insulation being used with pir. The multi foil suppliers claims no vapour barrier is needed when using their products.
Good question I have seen some roofs fail but probably because they didn't understand how to install the products correctly. Yes you can use the multi foil as a vapour barrier however you must type all joints as per manufacturers specifications personally I love the stuff however haven't fitted much of it
Thanks so much for your videos - I've found them super helpful. I have a question on something thats not been covered yet though, if you dont mind! I have a pitched roof that has 100mm of joist on show on the inside every 600mm and tongue and groove pine behind it. Externally under concrete tiles I imagine there is some kind of PIR. I'd really like to add another 80mm of PIR internally between these joists but I'm unsure if I need to leave an air gap as there is no venting as its all internal. Do I just push the PIR flush with the tongue and groove and air seal it all? thanks!
This is covered in other videos. However, the key to this is airtightness from the inside and ventilation on the outside under the tiles. The ventilation must be through ventilation air tightness must be achieved internally under the plasterboard if possible, using a vapour barrier if you do that everything should be okay
Thanks for all the videos you do Steve. I'm retrofitting insulation between the rafters of a cold sloped roof, so sloped ceilings in some of the rooms, and the bit I'm not sure about is how to seal the vcl at the perimeter of the ceilings to the brick/block plastered walls? Novia say you need 150mm of overlap when joining vcl layers so does that 150mm also aply for perimeter joints? Does that 150mm need to be ran down the wall? Do I need to chip off the plaster to hide the vcl. Will the new plaster stick to the vcl? I'm tempted to just butyl tape 10mm onto the wall so that the new ceiling plasterboard covers it, but is that 'airtight' ?
As you are starting to realise there's no room joined up, thinking with this junction so what you're trying to do is to make it airtight and make it a tie for its lifetime. The butyl tape is very good. Can you plaster over the plastic? No 150 mil millimetres is obviously the guideline. The butyl tape is only 25 mil wide so theoretically you could drop the 150 mm to the 25 mm as long as everything is airtight. Plastering over 25 mm would not be a problem even if it didn't stick.
Hi Steve, I have spray foam insulation upstairs in my dormer with the breathable card behind it. Do I still need to put on a vapor barrier bearing in mind that I have vented soffits, and a ventilation hole cut in the wall with a core bit albeit below the ceiling? It's not a flat roof.
Depends on what you're doing 30 mm is very very thin 50 mm we used to do a lot but you can tell when installing it's still not as good as at least 100 mm 100 mm is where I would go
I have a question..I have a void space. I was going to put celotex on the inside of the void up against the plasterboard by it's studwork . I found out there is no vapour barrier. All I have is 100mm of fiberglass insulation in the studwork. Can I take out the fiberglass. Line it with a vapour barrier then celotex over it? Baring in mind the vapour barrier won't be flush against the back of the plasterboard because of the studs. Told I can't insulate the rafters so it has to be the plasterboard. How can I put a vapour barrier
Hi Steve, love the detail in your videos, you said you prefer warm roofs, I have a question you might be able to answer, I am building a garden room with a warm roof, when I done the roof I fitted a polythene membrane, now I’m doing the inside the walls are 5 x 2 with 100 mm kingspan friction fitted, the question was do I need to put another membrane on the ceiling as I’m having 15 downlighters installed, I was going to use double sided tape around the timbers to get a good seal on the wall membrane at plate height. Many thanks Tony
If its a warm roof the vapour barrier is under the insulation that is over the joists so the space under the choice is classed as internal space you don't even have to have a ceiling you can put in as many likes as you want to because your vapour barrier is above that space. If however you made a mistake and put your vapour barrier lower down then you have a problem. The first problem is the vapour barrier is in the wrong place! The second problem is if you cut holes through it for the lights it's not gonna work. The good news is that even if you do put the lights in and you do cut through that lower vapour barrier warm roofs are very forgiving and it probably will still work.
The problem with all this is, it's time consuming and not feasible for the trade people and customer. Customer isn't going to pay extra for all this time spent. PIR and lofts don't go well. Time we thought of other materials and construction methods.
Hi Steve hope your well.i totally get the importance of a vapour barrier but how do you maintain it around a twinwall wood burner flue I don't see it's possible?
@@SteveRoofer with a twinwall flue u have to have a minimum of 50mm air cap around and nothing combustible attached to the flue I guess you could attached the vapour barrier to the back of the lead slate
Are there any "paint on" barrier solutions that could be used like stuff used on roof surfaces? I have a loft with Bobtail/Stub end type eves full of timber struts which I want to retain on the warm side for storage amongst other things but the thought of trying to fit & join bits of membrane between & to all of the timber struts hurts my head just thinking about it!
@@SteveRoofer Theres a few for come up on Google for sale in the UK. Think I may have to a look into them as like I say theres just no way I can get a sheet membrane around all the timbers jutting out everywhere. I don't think TH-cam allows links but if you were interested theres a video on YT called: CPD Intelligent Membranes liquid airtight vapour control barrier CPD fluid applied airtight membrane
@@SteveRoofer I've now actually tried out 2 types of paint on barriers, although I have only used them for sealing around small tricky areas & I stuck with traditional methods for the large flat surfaces such as barrier sheets or joining the included foil faces on PIR boards as these work out much cheaper. I used fibre reinforced paints that are specifically designed for for complex areas such as where roof timbers penetrate PIR boards etc from Intelligent Membranes CPD & a cheaper product from PermaSEAL (seems just as good) & as long as they last as long as they claim to I have to say they are excellent. Very quick & easy to apply.
Hi Steve, I must say you have produced some great information upon your youtube channel regarding general roofing techniques. I'm currently working on a personal project and would like to pick your brains regarding AVCL for a pitched vaulted cold roof. Would you mind if we engage in a brief corespondance on the subject. Thanks in advance Karl
Very interesting, just as I try to erect the walls of my garden room room this week. However, I have decided to use some Kingspan insulated roofing panels instead of traditional, joists + PIR + osb + epdm. Any comments of this type of system? I'm still interested in doing what I can with the wall though so this is still incredibly interesting. Many thanks.
If the Kingspan metal roof has insulation under it you don't need a vapour barrier this is all discussed on a video I did three weeks ago Condensation/Sweating on garden office roof th-cam.com/video/dHrI3EqEXW0/w-d-xo.html&ab_channel=SteveRoofer
Great video 🙏🏻 quick question please, my architect specified a 1000gauge vapour but the builder went for the 500gauge. Should I panic and ask him to put the 1000gauge as specified ?
Both are probably wrong. Normally it has to be 1200 gauge to get to the correct standards its all down to what the vaper resistance of the material is so look at the manufacturer's expectations with Air Vapour Control Layer (AVCL) its not just how good it is its how its fitted a well fitted AVCL that is not the correct standards but fitted correctly and is airtight will probably work. A very good AVCL fitted badly doesn't work.
Hi Steve Just wondering how would you recommend sealing a cold roof vapour barrier to internal block cavity wall? All examples I see are a complete timber frame, sealing walls and ceiling. Thanks
Hi Steve, do you have any information regarding adding a vapour control layer to a solid brick wall? I have a 2.4m x 1.7m small add on at the back of my house which is constructed from solid brick walls which is to be a cloakroom toilet and utility room. Before I fell down the rabbit hole of vapour control layers I was set to dot and dab with insulated plasterboard. If a vapour control layer is added before the plasterboard this means I would be unable to dot and dab? Given the very limited space I want to refrain from having to batten the walls as things just about fit as is. Any advice would be massively appreciated
A lot of people get very hung up on vapour control layer as it's not necessarily the vapour control layer that is a problem. It's controlling the movement of air what you're trying to do is put in a air barrier to stop the movement of air through a structure. So an air vapour control layer that should always go on the warm side of the insulation. The most important part of this is the air barrier not the vapour barrier so basically just keeping the construction airtight is the most important thing
I am doing a flat warm roof with a twin walled stove flue passing through, any thoughts of how i would go about this, with regards to the vapour barrier? Great video as always - Watched a lot of your videos and they are all very informative!
It's not difficult just make sure you seal it correctly and take the vapour barrier up above the height of the insulation you may want to put a piece of insulation above the roof level justice help stop thermal bridging
Hi Steve. I’m currently doing a loft conversion with a cold roof. I will be putting 100mm PIR in between the joists and 50mm PIR over. Do I need a VCL layer if all the PIR joints are taped? If so does it go on top of or behind the 50mm PIR?
you always put the air vapour control layer on the warmest side of the insulation press. You can't put it that far down it's got to go just over the top of the Joyce you always put the air vapour control layer on the warmest side of the insulation press. You can't put it that far down it's got to go just over the top of the joists and under the 100 mm PIR
Sorry I'm confused by this reply, the vcl goes directly onto the joist (so between the two layers of pir) or under the lowest pir layer (room side, the warmest side) ?
Hi I have a small shed with a cold roof, all timber frame, can I use 2 layers of 2.5mm kingspan to make 5mm, would I be okey to glue the kingspan together?
Hello Steve really enjoyed your videos. Say I have a situation that I need some help with. If I sent you some pics of same would you mind commenting. I realize the issue is likely poor ventilation and what I believe to be improver vapour barrier installation. Would you be ok if I sent you a few pictures of same for your comments.
Yes, send them through I'll have a look for you I do charge if it gets complicated but for small things if it's only gonna take me a few minutes no problem Steveroofer@gmail.com
Would a PVC pond liner work as a vapour barrier ?? because I have a green roof it is already installed and my OSB is starting to rot from the inside so I am planning on changing it to a warm roof system
@@SteveRoofer I can see what you mean. I am low on money so maybe I will just improve the ventilation, both options involve taking the roof off anywhere in that case anyway. Life is a Lemon sometimes
Howdo mate. Can't find a more immediate way to message you..... Have you ever had any problems, or have you ever primed kemperol to rubber/sarna/armourplan etc?
Yes, we have tried all of those and realistically as long as all surfaces are clean and dust free. You can normally get away without a primer. However the manufacturers don't like you not using a primer. We always make sure that the joint is secured using termination bars also
@Steve Roofer cheers mate. Didn't want to ask kemp reps as it would just open a can of worms, we've had them out to look over our work, but only use it a few times a year... It looked like normal single ply, whatever system, but turned out it had a very fine paint on it. The paint was leaching an oil or something, and nothing would stick. Fine grinding, loads of acetone and the clear, heavy duty primer sorted it anyway (ac primer?). Generally only use termination strips on vertical, and always make sure that the edges are well bled in. We normally do a catalyst heavy paint mix to test it anyway, but experience has taught us that it sometimes looks like it has stuck, but later peels. So normally use the primer anyway. We'd never come across this though. (It wasn't a full roof, to be clear, just several repairs against square penetrations, the surveyor couldn't get to the roof to see what it was, he'd assumed it would be OK! He wont be doing that again.) Cheers for the response anyway. Sorry for my very long reply. Every day's a school day.
Hi Steve, Great Video thanks. I am in the process of installing a vapour barrier (Novia STRP Pro Premium) in a new basement, this has a Foam filled hybrid roof with isothane, this was done due to design limitations, we must ensure a very well installed high spec vapour barrier is in place to prevent condensation and will do so with the Butyl tape and overlapping tape which I have. the vapour barrier is going to continue down the walls internally which are metal stud 50mm with PIR board in between, The ceiling is a metal frame dropped ceiling circa 70mm gap above and the same approach will be taken here with the butyl tape and vapour barrier onto the metal frame before the plasterboard goes on. my question is in regards to sockets. Any suggestion for this? my approach is going to be to cut out space for the sockets from the PIR board, cut across the vapour barrier and then patch in a recess using the butyl tape and small piece of vapour barrier in order to ensure no gaps, is this the right approach for this? as otherwise there would be just gaping big holes behind the sockets in the vapour barrier. Its fiddly but I cannot see another way?
These ideas seem quite pedantic (over the top) considering you still need ventilation to compensate for stuff causing moisture.. Humans, cooking, washing
If you are going to glue down your insulation yes use the primer if you are scaring it down with my preferred method thermaly broken fixings then no need to use primer
Yes I do believe the tapes will last for the lifespan of the building because they are hidden there is no UV and nothing else that can get to them to make them deteriorate they're also very flexible
I don't understand what you mean when you say you only do warm roofs, you don't do cold roofs. Can you explain? what is a warm roof and what is a cold roof?
the woman is where the insulation laid over the top of the supportive timbers. Cold roof is where the insulation between the joists just above the ceiling and roof itself is cold, because the heat from the room below is kept away from it by the insulation
why would you acknowledge how hard it would be for anyone to find the correct materials, and not even list them lol Ilove your expert information that you give for free, but this is not. auser friendly video :-(
why don't you compare these tapes with duct tape... the marginal increase in insulation doesn't cover the price difference. this is just more blablabla rules written by the big industrial suppliers.
This whole vapour barrier thing is a nightmare because it has to be broken for most lighting and fixings etc sockets. For a cold roof if the 50mm void above the insulation is continuous from vented soffit to soffit in a garden room a few holes in the VB won’t hurt too much as you are getting that moisture straight out of the roof space? Best thing we could all live in is a open barn no condensation problems then ha. Keep up the amazing work
Yes, the whole thing is a big problem and it's getting worse because we are stopping the transfer of energy from inside of property because we are installing insulation. The transfer of energy will help dry. The timbers in the construction now we have not got the energy to do so the timbers could stay colder and be wetter for longer that's causing the rot and decay, so we totally have to change the way we construct things and using the warm roof construction method is the best way.
I'm planning on pulling down ceiling and pitched roof and retrofitting better insulation, worth installing a VCL at the same time? What about the stud partition walls, do I just seal it against the wood?
@@SteveRoofer Steve, planning on taking out a lath and plaster exterior wall in an old 1800s stone house (no render, so the stone is permeable). Plan to put up 50x50mm studwork (trying to save space as well) with a small air gap, PIR in between the studs, then board and paper it. Does it need an extensive VCL like this, given that the other walls and ceilings are still lath and plaster that just have rolls of glass wool behind them? (this was the only wall that couldn't be accessed from behind).
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Great info Steve but you do realise that it's just not going to happen. Rightly or wrongly your average builder is not going to take that must care over the detailing and building control certainly don't pay much attention to it.
Constantly changing regulations and standards just add to the problems. We are having to price for ever increasing insulation requirements and still remain competitive AND keep our guys employed AND make a decent living for ourselves. Try telling a customer that your quote is more expensive because you have got to seal the AVCL with the special (ie expensive) butyl tape, oh and yes we cant use the same PIR that we've always been able to use for years, we now need to use this special (ie more expensive, and no doubt unobtainable from my normal supplier) PIR.
I'm just glad that i'm old enough to retire soon and leave all this behind me.
IF the specification is given to a builder / roofer they have to do the work correctly or will be held responsible. Hidden costs in materials and labour are horrendous when you look at the correct way of doing this. Easily missed when tendering. Because you cannot see this once the job has been finished it's never installed correctly this can cause problems and huge costs at a later date. There are other ways of doing this and I will be going into those in other videos shortly.
Customers that care about these things and will pay for it are there.
Hi. How do I find a roofer that can doth this vapour control
I cannot hear any sound?
@@doreenbritton5828 It's very unlikely you will, if you can even find one other example on TH-cam etc of a roofer/builder going to these lengths I'd be amazed to say the least. This is the gold standard... but to be fair most customers probably wouldn't want or couldn't pay the extra for this.
Some good information in your videos! A new sub from me. Looks like we will all be living in polythene bags! warm but no fresh air in? Where is all the moisture going to go created in the home? When everyone shuts up for winter unless you have ventilation you’re going to be breathing in stale air? Would be nice to go into one of these sealed homes and see what the co2 levels are with a home not breathing! or do they have heat recovery air in/out vent fans. This could all be done to aid killing you off earlier with poor air quality. Only my thoughts I live in a costal old town and the buildings are cold but they breathe and have lasted 100s of years some simple upgrades have halved the heating costs, upgrading loft insulation and cellotex on the inside of the external walls, obviously double glazing would help but not permitted in conservation areas.
Without a MVHR these super insulated homes run dangerous levels of CO2. I did a little experiment in our place, in the kitchen (super insulated) with 5 of us in there for lunch the CO2 goes from 420-1100ppm (no MVHR). That is not going to kill us but its not good for working in - just feel very sleepy. I've built a number of places with MVHR units and it is a revelation, its like being outside in the most fresh day but with the warmth you'd expect inside and no wind. They are quiet and can be set to kick in/ up a gear on higher CO2 / occupancy. It's like everything though, if the house is properly insulated as per this video with MVHR it's going to be amazing...but cut a few corners or lots of them (as many builders do) and the will catch up and bit the homeowner hard, especially if the person who has to make the repair doesn't understand what's really happened and we have such a shortage of builders who really understand the mechanics of this.
As long as the designer properly explains to the client why the cost of their build is double what was expected, great system.
This whole vapour barrier thing is a nightmare because it has to be broken for most lighting and fixings etc sockets. For a cold roof if the 50mm void above the insulation is continuous from vented soffit to soffit in a garden room a few holes in the VB won’t hurt too much as you are getting that moisture straight out of the roof space?
Best thing we could all live in is a open barn no condensation problems then ha.
Keep up the amazing work
That's why in Norway it is standard to have the plastic layer then stud it out with a 2x2 the other way and now we have a service cavity for electric and water without needing to make any holes in the vapor barrier
Another great video! Wasn't sure what you meant by air vapour control layer in the other video, so this explained it beautifully. Will have to look into it after I finish the initial work I'm doing.
Hi Steve, nice to find you on here! I'm always watching building videos, trying to learn something new. Looked for a video on vapour barriers and thought "Hey I know that fella!" Hope you're keeping well 👍
Your videos are so spot on 👍…. The question I have is …. Can you use black DPM as a vapour Barrier??? … on walls or ceilings .
The research I have seen is full of so much conflicting advice . So I thought I would ask the main man !!
Your advice will be gold
All the best
Pete 👍
I had the need to use a thermal imaging camera once. When digging deeper, I found out about surface emissivity.
If you look into that you will realise that a thermal imaging camera does not magically measure the surface temperature, all it does is measure the intensity of the infrared radiation emitted.
Different surfaces have different emissivity's, so for the same temperature, they emit different amounts of infrared radiation, so the temperature measurement is really an approximation, but can be used for comparative purposes when done on the same surface material.
The vapor / air barrier and insulation should be on the exterior of the structure.
Ridiculous overkill. Most are low occupancy garden rooms , no steam from kettles , shower rooms , kitchens etc . I’m convinced that these big businesses selling these products are brain washing people into buying all these products unnecessarily.
I built a garden room 25 yrs ago with none of these products, granted it’s not as well insulated as I would like , but it’s still stood and I’ve never had a problem with damp or moisture.
Walls are 3/4” ply , 4” fibreglass insulation, plasterboard and skimmed , never had a spot of moisture or damp damage and it used to house a spa tub.
This is for ALL constructions that involve timber frame or SFS (light steel frame) type builds. This is not just a home office / garden building way of constructing things. Passive house building is a good example where this sort of methodology is used, but very common in modern construction types, both domestic housing and light commercial.
If you're a professional person you have to do things correctly or you will be held responsible in the video I just show the correct way of doing it
For context Steve works in South London where in many areas that a house without a loft conversion (read timber room built like this) is the odd one out. All new builds will have a habitat room in the roof down south. This is very relevant to house building, extensions and the roof, he is just standing in a test rig at ground level.
@@loneturk3y for new builds that are energy efficient that means all new extensions loft conversions and new houses and flats we have to be really careful with how we control the internal environment and this may mean adding an air vapour control layer. Sometimes the house may be designed to be breathable in which case a vapour control layer may not be needed or can be of lower quality.
I can’t imagine this being a good idea in an old house. The guys working on stone built houses without damp courses stress the benefits of the wall being able to breath, so controlling the water in the wall
Fair enough doing everything to the highest standard but I don't buy into the idea of issues without taking things to this level.
I have a cold roof garden office and loft.
No vapour barrier in the loft (before I knew as much as I do now), PIR insulation with a good air gap behind. Down lights cut out. No issues.
Office I did to the best of my knowledge at the time. Warm roof was not possible due to height restrictions and converting an already brick building. Internal brick was painted with black jack. As it was bone dry when I purchased the house I decided to do a new coat of black jack, air vents either side of the roof, left a big 50mm air gap on top including cross ventilation (furrings), PIR insulation between joists on ceiling, downlights cut out with no big attempt to seal, used cavity insulation for walls, used a green vapour control layer all over, left big overlaps and used the cheapo silver tape for joints. Probably used more screws than needed for plasterboard. No issues.
If you paid a professional person to do the job and they didn't do it correctly and it went wrong who would you turn to to put it right? So professional people should do it correctly otherwise they could have some large claims against them
Just wondering if I were to insulate a internal external wall using celotex plasterboards would I need to use a vapour barrier
You are doing such a great job thank you for all your work!
Where are the links to manufacturers?
Sorry novia.co.uk/
Once a building is airtight sealed in this way, how do you let moisture out? Especially in a bathroom or kitchen. I will be building an extension in Sept with both these rooms, and would like to get it right. Apologies if this something covered in your videos, thanks
Building regs require bathrooms are vented, either by window or extractor fan.
Sound only works on my left ear with this video but its a great explanation than the course I bought
works ok for everybody else perhaps go to speck savers!
Is this required on a SIP construction building?
on a standard loft conversion, there is a sloping roof to the front and a flat roof over the center and rear dorm. How do you do a warm roof? it will be hard to do a warm roof on the sloping part so how can you join a cold roof to a warm roof, or am i asking the wrong question, should I be asking how to do a warm roof over the sloping part.
On the rig that I'm working on I will do a video regarding that however to answer your question you do a cold roof over the pitch area and a warm roof over the flat area.
@@SteveRoofer thank you sir, that will be an interesting video, I'm looking forward to it
Hi great video thanks. How do you deal with lightning cables and downlights when having to use 150mm celeotex between the rafters and then 50mm celeotex below that, ie vapour barrier when having downlights and also having to deal with restricted height
Thanks for the info Steve. I’ve got a 200yo stone cottage on the outskirts of Glasgow and I’m just about to start insulating myself…
Is it necessary to insulate walls that aren’t a part of the exterior wall, separating walls if you like?
I’ve decided to use ROCKWOOL for its various properties, one being that rodents don’t like to live in it, and we definitely have mice.
I’ve also ordered the Novia green barrier, silver foil tape and butyl tape from Novia too.
Thanks in advance 😊👍
Steve will you do another thermal camera scan now it's got an air tight layer. I remember some warm spots due to air migration, have these been reduced now air movement is controlled?
Unfortunately I cant as I ran out of materials but I will do using the next batch of AVCL,s i play with
Hi Steve,
With walls and ceilings sealed like this, putting any fixtures to the walls/ceiling is basically a nono? Eg wall plugs, TV brackets, shelving support etc. Everything which require some type of piercing through the plasterboard will likely puncture the vcl.
Basically you are saying, insulation layer of 150mm + gap/space, plus 75mm all round framing to accommodate any fixings...
Thank youmfor the tips Steve - Have a happy Festive Season 🎄
Happy holidays!
@@SteveRoofer Merry Christmas please. This isn't America
Great videos Steve. I wonder if you could help with one question. On a timber frame garden room, with a warm flat roof. I’m struggling to think of a way of forming an air tight VCL seal, in between the roof joists, where they sit over the stud walls. Would it be a problem to add an additional VCL on the underside of the joists like on a cold roof, and tape to the wall VCL, or would this cause an issue with an additional layer, as there is already a VCL under the insulation on the warm roof. Thanks in advance.
Hi Steve.
Thanks for sharing, I am doing a conservatory with a flat cold roof, I have used 6x2 timbers at 2.5m long, then used 6x2 cut down to foam my slope so it is raised 6" over 6ft, I will be inserting vents into the soft to allow air flow through, internal I will do the vapour barrier at 130 as in your video,👍
My question is the breeze block and how would I seal the vapour barrier to these🤔
Thanks
Sean
I would have liked to have seen you put the vapour barrier up
What would be your opinion about where or if any vapour control layer/barrier in a suspended timber frame ground floor, new build, access underneath via crawlspace , with pir insulation in-between joist.
I am thinking from bottom up , breathable roofing membrane , joist with pir insulation between insulation to top of joist providing air space beneath below to membrane, next is where I'm lost, is it osb board then vapour and some foam over to protect from Finnish laminate flooring or , vapour barrier then osb board or and vapour lol thanks ,great videos and information in all your roofing details
I would ask one of the vapour barrier suppliers for their help so far I have found them very helpful try Novia
Nice video Steve. How to insulation and vapour barrier a log stove flue through a cold roof?
I think I replied to this earlier just make sure it's well sealed with the vapour barrier the vapour barrier extends to the height of the insulation and perhaps insulate hire around the pipe to stop thermal bridging
I have a room that is in part below an open air Deck access (walkway). The ceiling is concrete slab. From watching your videos I must create a warm roof as to insulate internal there would be no air flow between the concrete slab and insulation? This correct thinkingness on this matter?
When you put insulation over a concrete slab you have to insulate all edges so you get no cold bridging and you don't need airflow with a warm roof
A good followup video after this one would be one showing the damage a cold roof can get after installing PIR plates taped only with silver tape (the regular one, not that strong stuff). I was assisting last week a company that only used PIR plates and pur foam to close the gabs and some silver tape. Where the PIR met a stone wall they put the silver tape decoratively over the pur foam but not on the wall because that would let go.
No Air Vapour Control Layer was added. The customer of course was very happy, but what does she know? If there will be damage because of wood rot, years after, will he/she be able to put that liability to the installation company?
I find this all very disturbing.
Yes its not nice for some people when it all goes wrong
Great demo. Is MVHR essential if you seal a room/house to this standard? What is the new style insulation your mentioned in a previous vid. Moving away from PIR?
IM about 4 videos away from showing the new way of doing things. Yes MVHR is going to be something we should all be using as we seal up our property
Great. Thanks Steve
Hi Steve,
Would really appreciate your opinion if you had a minute,
Would this Vapour barrier spec be suitable for a standard cold roof in a medium occupancy garden room:
Semi transparent green visqueen. AVCL
SD - 128
MNs/g - 633
Permeability - 0.21
Thickness 0.3 mm
No excessive mouisture being produced, RH being kept around 50%.
All airtight details and correct tapes used.
Many thanks if you have time to respond.
Yes that will work just make sure you fit it as best you can and as airtight as you possibly can
I’m having the kitchen plastered which has a cold roof. I’ll be fitting the vapour barrier to the ceiling but where it meets the top of the wall, can this be taped down then plastered over? Thanks
Yes type it to the walls make sure that it's completely airtight and no air can get up into the void above
Good video Steve thank you
Any recommendations other than expanding foam to seal kingspan into stud work? With thanks Mark
New building regs are now suggesting that we all use this new type code Gatotape expensive to buy expensive to install and the only thing on the market at the moment
Need some advice Steve I have been told you can't fibreglass over OSB board coated with bitumen paint as it won't stick so if you cover with 3mm hardboard will that be ok to fibreglass over thanks, your help will be much appreciated
It's not so much that it doesn't stick it reacts with the tar so all you need to do is put a barrier between the two and you're good to go 3 mm hardboard you could do but why are use glass fibre because it is a very bad roofing material use something more flexible
Hi Steve great videos I’ve watched so many, can I ask a question? I’m doing a cold roof on my new wooden workshop because of height restrictions, I’m happy with that process. However looking online I’m really struggling to see whether there needs to be a air gap for ventilation in my walls as well, like the cold roof needs?
From the outside in, the walls will be 45mm tongue and groove, 100mm cavity slabs, vapour barrier, then some sort of inside wall like OSB, thick enough that I can screw into without reaching the vapour barrier. So do any of those layers need an air gap? Many thanks I hope you get the time to reply! :)
Wall design is different to roof design as there is normally less present on them. A vented rain screen ie outer layer is always recommended but seldom done
@@SteveRoofer thank you that’s sort of what I thought, in a roof it’s so critical because of heat rising and gravity causing condensation to sit. But in the walls I should be ok, especially as my 100mm rock wall slabs are breathable? It’s to late to add a breathable membrane unfortunately I’m too far into the build
Every customer ever: "yes I want a valted ceiling with 100 downlights"
Got to tell them no !
But they never listen
I don't want downlighters 😀 there has yo be an exception I guess to prove the rule.
Yes everybody wants down lighters and unfortunately builders just tend to give customers what they want without understanding the consequences
Hey mate, how's things? How much PIR insulation would you recommend for a flat roof on a kitchen in England? Thanks
New building regulations come out this week and we think the new regulations will mean that on a retrofit roof the thickness of insulation to get to the correct U value will be 150 mm it used to be 120 mm
@@SteveRoofer Thank you Steve you are a life saver 🙏
I’m in the process of doing garage conversion, the more I watch your videos the more dismayed I get, I have a cold roof so I have to create a false sealing due to ventilation for building regs, getting into vapour barriers etc it now seems down lighters will affect that, it’s a bloody mind field and a costly one, how the hell do you put sockets in and wires through if it’s going through the vapour barrier, by the time I’m done the head height will be about 4 foot!
Unfortunately you are right in so many ways sometimes ignorance is bliss
Hi, great content. I'm learning loads. Quick question. On a warm flat roof,Should I put a vapor control under the ceiling joist aswell as the one under the insulation? Thanks
Be good to see a vapour barrier detail around a plug socket. They are the problem areas where it will be compromised. What do you suggest?
Hi Steve, what's your experience of multifoil insulation being used with pir. The multi foil suppliers claims no vapour barrier is needed when using their products.
Good question I have seen some roofs fail but probably because they didn't understand how to install the products correctly. Yes you can use the multi foil as a vapour barrier however you must type all joints as per manufacturers specifications personally I love the stuff however haven't fitted much of it
Thanks so much for your videos - I've found them super helpful. I have a question on something thats not been covered yet though, if you dont mind! I have a pitched roof that has 100mm of joist on show on the inside every 600mm and tongue and groove pine behind it. Externally under concrete tiles I imagine there is some kind of PIR. I'd really like to add another 80mm of PIR internally between these joists but I'm unsure if I need to leave an air gap as there is no venting as its all internal. Do I just push the PIR flush with the tongue and groove and air seal it all? thanks!
This is covered in other videos. However, the key to this is airtightness from the inside and ventilation on the outside under the tiles. The ventilation must be through ventilation air tightness must be achieved internally under the plasterboard if possible, using a vapour barrier if you do that everything should be okay
Thanks for all the videos you do Steve.
I'm retrofitting insulation between the rafters of a cold sloped roof, so sloped ceilings in some of the rooms, and the bit I'm not sure about is how to seal the vcl at the perimeter of the ceilings to the brick/block plastered walls? Novia say you need 150mm of overlap when joining vcl layers so does that 150mm also aply for perimeter joints? Does that 150mm need to be ran down the wall? Do I need to chip off the plaster to hide the vcl. Will the new plaster stick to the vcl? I'm tempted to just butyl tape 10mm onto the wall so that the new ceiling plasterboard covers it, but is that 'airtight' ?
As you are starting to realise there's no room joined up, thinking with this junction so what you're trying to do is to make it airtight and make it a tie for its lifetime. The butyl tape is very good. Can you plaster over the plastic? No 150 mil millimetres is obviously the guideline. The butyl tape is only 25 mil wide so theoretically you could drop the 150 mm to the 25 mm as long as everything is airtight. Plastering over 25 mm would not be a problem even if it didn't stick.
Great, thank you
Hi Steve, I have spray foam insulation upstairs in my dormer with the breathable card behind it. Do I still need to put on a vapor barrier bearing in mind that I have vented soffits, and a ventilation hole cut in the wall with a core bit albeit below the ceiling? It's not a flat roof.
Thanks Steve.
Will 30mm suffice? The price increase for 50mm is pretty significant.
Depends on what you're doing 30 mm is very very thin 50 mm we used to do a lot but you can tell when installing it's still not as good as at least 100 mm 100 mm is where I would go
I have a question..I have a void space. I was going to put celotex on the inside of the void up against the plasterboard by it's studwork . I found out there is no vapour barrier. All I have is 100mm of fiberglass insulation in the studwork. Can I take out the fiberglass. Line it with a vapour barrier then celotex over it? Baring in mind the vapour barrier won't be flush against the back of the plasterboard because of the studs.
Told I can't insulate the rafters so it has to be the plasterboard. How can I put a vapour barrier
Hi Steve, love the detail in your videos, you said you prefer warm roofs, I have a question you might be able to answer, I am building a garden room with a warm roof, when I done the roof I fitted a polythene membrane, now I’m doing the inside the walls are 5 x 2 with 100 mm kingspan friction fitted, the question was do I need to put another membrane on the ceiling as I’m having 15 downlighters installed, I was going to use double sided tape around the timbers to get a good seal on the wall membrane at plate height. Many thanks Tony
If its a warm roof the vapour barrier is under the insulation that is over the joists so the space under the choice is classed as internal space you don't even have to have a ceiling you can put in as many likes as you want to because your vapour barrier is above that space. If however you made a mistake and put your vapour barrier lower down then you have a problem. The first problem is the vapour barrier is in the wrong place! The second problem is if you cut holes through it for the lights it's not gonna work. The good news is that even if you do put the lights in and you do cut through that lower vapour barrier warm roofs are very forgiving and it probably will still work.
What are the details of the supplier Steve? I can’t seem to find them in the description
Sorry novia.co.uk/
Thanks Steve 👍
Whats the best way for light fittings? Without breaking the vapour barrier?
The problem with all this is, it's time consuming and not feasible for the trade people and customer. Customer isn't going to pay extra for all this time spent. PIR and lofts don't go well. Time we thought of other materials and construction methods.
Yes more videos coming with different ways of doing things
Would this then need mechanical ventilation in the room created?
Probably depends on how the room is ventilated
Hi Steve hope your well.i totally get the importance of a vapour barrier but how do you maintain it around a twinwall wood burner flue I don't see it's possible?
It may sound silly but as best as you can just try and keep everything airtight
@@SteveRoofer with a twinwall flue u have to have a minimum of 50mm air cap around and nothing combustible attached to the flue I guess you could attached the vapour barrier to the back of the lead slate
Good videos in trying to explain to laymen. Looking for some help on insulating a large wooden garden shed
send over by email steveroofer@gmail.co.uk
Are there any "paint on" barrier solutions that could be used like stuff used on roof surfaces? I have a loft with Bobtail/Stub end type eves full of timber struts which I want to retain on the warm side for storage amongst other things but the thought of trying to fit & join bits of membrane between & to all of the timber struts hurts my head just thinking about it!
Unfortunately I don't know of any paint on vapour control layer however in America I note that they tend to use some of them
@@SteveRoofer Theres a few for come up on Google for sale in the UK. Think I may have to a look into them as like I say theres just no way I can get a sheet membrane around all the timbers jutting out everywhere. I don't think TH-cam allows links but if you were interested theres a video on YT called: CPD Intelligent Membranes liquid airtight vapour control barrier CPD fluid applied airtight membrane
@@SteveRoofer I've now actually tried out 2 types of paint on barriers, although I have only used them for sealing around small tricky areas & I stuck with traditional methods for the large flat surfaces such as barrier sheets or joining the included foil faces on PIR boards as these work out much cheaper.
I used fibre reinforced paints that are specifically designed for for complex areas such as where roof timbers penetrate PIR boards etc from Intelligent Membranes CPD & a cheaper product from PermaSEAL (seems just as good) & as long as they last as long as they claim to I have to say they are excellent. Very quick & easy to apply.
Hi Steve, I must say you have produced some great information upon your youtube channel regarding general roofing techniques. I'm currently working on a personal project and would like to pick your brains regarding AVCL for a pitched vaulted cold roof. Would you mind if we engage in a brief corespondance on the subject. Thanks in advance Karl
steveroofer@gmail.com
Very interesting, just as I try to erect the walls of my garden room room this week. However, I have decided to use some Kingspan insulated roofing panels instead of traditional, joists + PIR + osb + epdm. Any comments of this type of system?
I'm still interested in doing what I can with the wall though so this is still incredibly interesting. Many thanks.
If the Kingspan metal roof has insulation under it you don't need a vapour barrier this is all discussed on a video I did three weeks ago Condensation/Sweating on garden office roof th-cam.com/video/dHrI3EqEXW0/w-d-xo.html&ab_channel=SteveRoofer
Great video 🙏🏻 quick question please, my architect specified a 1000gauge vapour but the builder went for the 500gauge. Should I panic and ask him to put the 1000gauge as specified ?
Both are probably wrong. Normally it has to be 1200 gauge to get to the correct standards its all down to what the vaper resistance of the material is so look at the manufacturer's expectations with Air Vapour Control Layer (AVCL) its not just how good it is its how its fitted a well fitted AVCL that is not the correct standards but fitted correctly and is airtight will probably work. A very good AVCL fitted badly doesn't work.
Steve, great vid! Do you have a recommended supplier of all things vapour control?
Well, I only use one vapour control layer and let's alutrix 600 and that's only used on warm roofs I don't do cold roofs
How does the thermal camera look after this treatment?
Look after what treatment?
Hi Steve
Just wondering how would you recommend sealing a cold roof vapour barrier to internal block cavity wall?
All examples I see are a complete timber frame, sealing walls and ceiling.
Thanks
I'm no expert but I think the double sided Butyl tape shown in this video may be your best bet as is seems to stick to anything.
Maybe relevant for a passive house but not for normal bloody garden rooms
why dident you record with thermal camera to see if this extra work acualy makes a difrents
Please explain why you need to ventilate cold roof if vapor barrier block all the moisture coming in it ?
Steve can you recommend a vapour barrier for a roof I've put on my conservatory please mate
Hi Steve, do you have any information regarding adding a vapour control layer to a solid brick wall? I have a 2.4m x 1.7m small add on at the back of my house which is constructed from solid brick walls which is to be a cloakroom toilet and utility room. Before I fell down the rabbit hole of vapour control layers I was set to dot and dab with insulated plasterboard. If a vapour control layer is added before the plasterboard this means I would be unable to dot and dab? Given the very limited space I want to refrain from having to batten the walls as things just about fit as is. Any advice would be massively appreciated
A lot of people get very hung up on vapour control layer as it's not necessarily the vapour control layer that is a problem. It's controlling the movement of air what you're trying to do is put in a air barrier to stop the movement of air through a structure. So an air vapour control layer that should always go on the warm side of the insulation. The most important part of this is the air barrier not the vapour barrier so basically just keeping the construction airtight is the most important thing
I am doing a flat warm roof with a twin walled stove flue passing through, any thoughts of how i would go about this, with regards to the vapour barrier?
Great video as always - Watched a lot of your videos and they are all very informative!
It's not difficult just make sure you seal it correctly and take the vapour barrier up above the height of the insulation you may want to put a piece of insulation above the roof level justice help stop thermal bridging
@@SteveRoofer Thanks for the reply
Hi Steve. I’m currently doing a loft conversion with a cold roof. I will be putting 100mm PIR in between the joists and 50mm PIR over. Do I need a VCL layer if all the PIR joints are taped? If so does it go on top of or behind the 50mm PIR?
you always put the air vapour control layer on the warmest side of the insulation press. You can't put it that far down it's got to go just over the top of the Joyce you always put the air vapour control layer on the warmest side of the insulation press. You can't put it that far down it's got to go just over the top of the joists and under the 100 mm PIR
Sorry I'm confused by this reply, the vcl goes directly onto the joist (so between the two layers of pir) or under the lowest pir layer (room side, the warmest side) ?
It also confused me mark. the warmest side would be between the 50mm pir and the plasterboard.
This maybe a silly question but what’s the difference between a warm and a cold roof?
Just look at my video on warm and cold roof explains everything
Hi I have a small shed with a cold roof, all timber frame, can I use 2 layers of 2.5mm kingspan to make 5mm, would I be okey to glue the kingspan together?
Yes that works stage the joints
@@HampsteadBuildersLt thank you
Hello Steve really enjoyed your videos. Say I have a situation that I need some help with. If I sent you some pics of same would you mind commenting. I realize the issue is likely poor ventilation and what I believe to be improver vapour barrier installation. Would you be ok if I sent you a few pictures of same for your comments.
Yes, send them through I'll have a look for you I do charge if it gets complicated but for small things if it's only gonna take me a few minutes no problem Steveroofer@gmail.com
Would a PVC pond liner work as a vapour barrier ?? because I have a green roof it is already installed and my OSB is starting to rot from the inside so I am planning on changing it to a warm roof system
Don't know I can only quote the correct specifications for a Air Vapour Control Layer (AVCL) however it may do but is is worth the risk
@@SteveRoofer I can see what you mean. I am low on money so maybe I will just improve the ventilation, both options involve taking the roof off anywhere in that case anyway. Life is a Lemon sometimes
Howdo mate.
Can't find a more immediate way to message you.....
Have you ever had any problems, or have you ever primed kemperol to rubber/sarna/armourplan etc?
Yes, we have tried all of those and realistically as long as all surfaces are clean and dust free. You can normally get away without a primer. However the manufacturers don't like you not using a primer. We always make sure that the joint is secured using termination bars also
@Steve Roofer cheers mate. Didn't want to ask kemp reps as it would just open a can of worms, we've had them out to look over our work, but only use it a few times a year...
It looked like normal single ply, whatever system, but turned out it had a very fine paint on it. The paint was leaching an oil or something, and nothing would stick. Fine grinding, loads of acetone and the clear, heavy duty primer sorted it anyway (ac primer?).
Generally only use termination strips on vertical, and always make sure that the edges are well bled in.
We normally do a catalyst heavy paint mix to test it anyway, but experience has taught us that it sometimes looks like it has stuck, but later peels. So normally use the primer anyway. We'd never come across this though. (It wasn't a full roof, to be clear, just several repairs against square penetrations, the surveyor couldn't get to the roof to see what it was, he'd assumed it would be OK! He wont be doing that again.)
Cheers for the response anyway. Sorry for my very long reply.
Every day's a school day.
Hi Steve,
Great Video thanks.
I am in the process of installing a vapour barrier (Novia STRP Pro Premium) in a new basement, this has a Foam filled hybrid roof with isothane, this was done due to design limitations, we must ensure a very well installed high spec vapour barrier is in place to prevent condensation and will do so with the Butyl tape and overlapping tape which I have. the vapour barrier is going to continue down the walls internally which are metal stud 50mm with PIR board in between, The ceiling is a metal frame dropped ceiling circa 70mm gap above and the same approach will be taken here with the butyl tape and vapour barrier onto the metal frame before the plasterboard goes on.
my question is in regards to sockets. Any suggestion for this? my approach is going to be to cut out space for the sockets from the PIR board, cut across the vapour barrier and then patch in a recess using the butyl tape and small piece of vapour barrier in order to ensure no gaps, is this the right approach for this? as otherwise there would be just gaping big holes behind the sockets in the vapour barrier. Its fiddly but I cannot see another way?
These ideas seem quite pedantic (over the top) considering you still need ventilation to compensate for stuff causing moisture.. Humans, cooking, washing
Hi Steve on the Alutrix website it says to use FG 35 primer even with the self adhesive vapour barrier
Can it be installed without primer
If you are going to glue down your insulation yes use the primer if you are scaring it down with my preferred method thermaly broken fixings then no need to use primer
@@SteveRoofer
Ok thanks for the quick reply
Will be screwing it down
Alutrix 600
Looks like a black mold factory.
Mix the high viz!
You’re by yourself!
But don't go telling everybody
I'm sure this is the correct way of doing things. But I very much doubt that anyone will.
Do you believe these tapes will last for 30+ years?. I don't.
Yes I do believe the tapes will last for the lifespan of the building because they are hidden there is no UV and nothing else that can get to them to make them deteriorate they're also very flexible
I don't understand what you mean when you say you only do warm roofs, you don't do cold roofs. Can you explain? what is a warm roof and what is a cold roof?
the woman is where the insulation laid over the top of the supportive timbers. Cold roof is where the insulation between the joists just above the ceiling and roof itself is cold, because the heat from the room below is kept away from it by the insulation
That’s a grow room, stop growing to pull the wool over our eyes….
No way you're a roofer with such soft undamaged skin 🤣👼👩🍼🧝♀️
And I thought you would never notice
why would you acknowledge how hard it would be for anyone to find the correct materials, and not even list them lol Ilove your expert information that you give for free, but this is not. auser friendly video :-(
the amount of how to videos this guy has that doesnt show you how to!! lol mate. put a load up and show us how!!
why don't you compare these tapes with duct tape... the marginal increase in insulation doesn't cover the price difference. this is just more blablabla rules written by the big industrial suppliers.
I agree with you, it's all going a little bit too farI agree with you, it's all going a little bit too far
All these updates are costly and in all honesty not needed.
The problem is, we are adding insulation and once we start doing that, we have to think of the consequences
This whole vapour barrier thing is a nightmare because it has to be broken for most lighting and fixings etc sockets. For a cold roof if the 50mm void above the insulation is continuous from vented soffit to soffit in a garden room a few holes in the VB won’t hurt too much as you are getting that moisture straight out of the roof space?
Best thing we could all live in is a open barn no condensation problems then ha.
Keep up the amazing work
Yes, the whole thing is a big problem and it's getting worse because we are stopping the transfer of energy from inside of property because we are installing insulation. The transfer of energy will help dry. The timbers in the construction now we have not got the energy to do so the timbers could stay colder and be wetter for longer that's causing the rot and decay, so we totally have to change the way we construct things and using the warm roof construction method is the best way.
I'm planning on pulling down ceiling and pitched roof and retrofitting better insulation, worth installing a VCL at the same time? What about the stud partition walls, do I just seal it against the wood?
In a roof always put a vapour control layer in walls it's not always necessary
@@SteveRoofer Steve, planning on taking out a lath and plaster exterior wall in an old 1800s stone house (no render, so the stone is permeable). Plan to put up 50x50mm studwork (trying to save space as well) with a small air gap, PIR in between the studs, then board and paper it. Does it need an extensive VCL like this, given that the other walls and ceilings are still lath and plaster that just have rolls of glass wool behind them? (this was the only wall that couldn't be accessed from behind).