You explained everything clearly , I’m a sixty six year old retired chippy and I love your channel and changes to the building good and bad as the years go ; thank you 👍🍺
I do like the subtle skills that come with time, like at 49 sec where the brickie throws a snot back on the mixing board without a second thought. Great video.
Another great video, cheers Roger, you're always very informative and knowledgeable. I look forward to your videos being released, keep up the great work!
just found this channel and thanks for the details on expansion gaps that was so useful, many thanks and will be cramming in alot of these videos now :D
Nice to see the DPC bedded on properly mortar above and below many brickies dont do it like that Roger this could be a point you could raise in one of your videos
Just came across your vids now on the extension..great vids. Love the knowledge dropping on the insulation and brickwork. Would love to learn more of these little details on building in future vids
All looks quality work well done. Don’t like the full full insulation in cavity though? Yo can be the best bricklayer in the world, but trying to keep a 10 mm void clear of snots realistically is a big ask. You just can’t beat a clear two inch cavity; it’s there to do what it’s designed to do ... keep water OUT👍👍
I always check things before builders do something. But I trusted our architect/engineer when he provided the specification drawings. Once the footings were finished I learnt that now the building regs require 150mm cavity instead of 100mm. Our footings were done with 110mm cavity (103mm brick + 50mm residual cavity + 60mm PIR insulation + 100mm blocks). Now I wonder if the building inspectors would ask to break the footing and redo with 150mm cavity :(
Interesting how the methods are different in Poland. Double walls are very rare here. Most popular is to build a house from air concrete blocks and then put 20cm styrofoam outside and then put plaster with mesh inside out 4mm thick.
t & g is a nightmare to lay/place. i'm foil taping my joints to ensure its air sealed but have to cut little notches out of tongue to slide in the 20mm then fill with expanding foam when next layer goes in. tip - put loads of ties in the very first course to fully support boards and keep level
Hi Munkmeister It is time-consuming I agree and stuffing 100mm Rockwool batts in is easier. Like your tip about placing loads of ties in the first course. We didn't and it rocks around. We just bashed the end of the board and the ties cut their own path. I thought about taping the joints but am not sure about the airtightness being that important. If the cavity is sealed there is very limited air movement in there.
@@SkillBuilder I have scrutinized many of your video's and if you are the foreman with the knowledge you have ,I would advise you to go back to college and retrain !
Expansion joint.. Interesting how we tend to forget and then "rediscover" things. Ancient Inca ( Maya, Aztec ect ect) were using something like that. Basically, on top of granite blocs there were T carved out and when they connected two blocs it created double T which they were filling in with molten lead. This is also why these structures were so durable.
Great videos, keep up the good work. Have a word with the guy using the chisel. He needs to grind the curls off the top. They can be dangerous if they fly off. I know a guy that was blinded by one.
Stopping the property breathing, is that a good idea? what about the condensation that these properties have been experiencing especially in the loft area? Whose bright idea was it in the first place to full fill the cavity and now the ridiculous 150mm full fill?
Thank you for the great video and invaluable insights. I have a question if using 50mm PIR in 100mm cavity (not T & G) do you use aluminum insulation tape to the joints between the pir sheets? also how do you get the PIR sheet to stick to the inside wall?
Gd work,if you put in xtra wallties,on the first 2 sections of thermboard insulation,it stops d board from buckling,and maintains a good tight fit up the wall,
Is there a way to use the normal 90mm×1200mm×450mm PIR boards (without tongue and groove edge) in a fully filled cavity like this? Any alternative way to close the gaps with tape etc?
I am loving the work and information you are providing and it is clear that the damp proof membrane and insulation work hand in hand, but what I cannot get my head around is how the break is done when you have a door space and the wall seems to connect the outside and inside together
@@letsgocamping88 Thanks for that, I am considering a pair of doors to open onto by back garden but I did not want to create a way that damp could bridge the gap and get into the house.
Older houses did used to close the cavity with brickwork. My window sills and reveals are this way. Acts as you suspected as a thermal bridge. I’ll be looking to insert some sort of cavity closer or over board with insulation in the future.
Hello again Roger. Just found your videos, Got a Good Tip for you when you build one skin of the cavity which ever you put the ties in .We put mf 7cieling Ali channel on the cavity ties To catch the Scott’s .helps with a Clean cavity. Cheers speak soon .jimmy Ps I also live in sw London
Very interesting video well done. I would like to know how the relationship between the cavity wall ties and the rigid cavity wall insulation works. Would I be right in thinking the insulation is cut to suit the wall ties? If so that must be quite a messy process as I am sure the cavity wall ties are supposed to be staggered vertically and horizontally. It must cause the bricklayer a bit of a headache if that is the case.
Hi Lisa Good bit of observation there and on some points they may be in vertical lines but I think you may be looking at either side of the pier and movement joint where they are in straight line on every course. The others are randomly staggered but they are every other course and laid in the block not under the perp because is hold them down better. We put one in every course either side of the windows and doors. At those points, it is tricky with that insulation because it is easier to push them through afterwards and point up rather than try and push the insulation over the ties. We used some Tiger ties at some points just to make life easier.
Actually look at 52 seconds, shoots you're statement to bits, 4:40, up pillar, only one wall tie on each course, don't get me wrong, really good work, inspectors and C of Works would never accept that in this area.
Sorry Lisa Call me thick but I don't completely understand the point you are making. You can see Mark pushing wall ties through the insulation on the edges of the window openings so they are in every block course around openings. Elsewhere they are spaced closer than 900mm on every other block course. At the movement joints they are in every block course. I am happy that you are taking the trouble to comment but I am struggling to see what is wrong or what the building control inspector could object to.
Hi Roger, great video. How does external insulated rendered cladding work with the cavity? Does it just mean no insulation is needed or would it leave a cold spot on the internal walls? Thanks
Hi Nick I have never seen EWI used with a cavity wall. It is mostly a way of insulating houses with solid walls and it gets a bit of bad press because there are often cold bridging issues. Basically, the difference between the insulated wall and the odd bits around the eaves or windows is so marked that the airborne moisture in the otherwise warm house hits that cold spot and condenses. It is a really good way of insulating because it leaves the thermal mass of brickwork on the inside so it gets heated but those odd areas where the insulation can't be applied is a huge drawback.
@@nickwalton8864 there's ways around those issues mentioned. You can get insulated sills passivesills.com/ and use a couple of thermal courses at the eaves and also at ground floor level which means zero thermal cold bridging anywhere. I've drawn up A rated houses using 200mm EWI and 215mm block work and its my preferred construction method by far. Some more info. passivehouseplus.ie/magazine/guides/the-ph-guide-to-external-insulation
Problem is getting a good builder who will install it correctly too many couldn't careless and you'd never know till years later (when you've got damp issues) that theyd installed it incorrectly.
Don't like the idea of the insulation with only a small cavity. The wall tie penetrates the whole wall and the drip on the tie becomes redundant. Even though you have clips which should stop the water ingress, its still possible with enough water for it to track. Plus in general if the outside block/brickwork is slightly higher than the inside the potential for tracking get exacerbated. BTW it's a movement joint not a expansion joint, on any plan its marked as MJ. Other than that great vid and quality bricky.
Looopy2u You are right expansion joint is not the right term because it is as much about shrinkage as the materials dry out as any expansion. There wasn't one on our drawing and I find this is often the case. As for the water ingress you have a point but the way the insulation sits around the ties means that very little would get past and then it has to soak through the mortar to appear as damp. That said this is a very exposed gable end and I will be watching to see if there is anything coming in.
Probably you have nothing to worry about, just a concern I have with this kind of close cavity system. Plus there are a lot of builders out there that are not at your standard so it would be easy for them to hide any high block work that would result in backward running ties. Maybe I've worked on too many 50mm+ cavity systems :D Hard to teach an old dog new tricks!
Normally the dpcs are on each skin but if you have water that needs to be directed to the outside then a wider stepped down dpc is used. This happens over lintels etc
Thin joint mortar will reduce thermal bridging in lightweight blocks. Cavity can't be filled with mineral wool insulation as it will become damp and start to rot. To many thermal bridges including wall ties.
Didn't you hear about billion of pound worth insurance claims arising from mineral wool used in cavity. It is breathable and therefore can accumulate moisture that travels true internal leaf, depending on pressure differences and damages structures organic materials.
Insulation Cavity Batt ROCKWOOL Thermal Cavity Batts are a semi-rigid full fill insulation solution for masonry cavity wall construction, suitable for use in extensions. It is easy to handle and install and provides a close fit against brick and blockwork. The batts are non-combustible and water repellent, yet vapour permeable. BBA certified for all exposure zones Acts as a cavity barrier Prevents water transmission from the outer to inner leaf Highest Euroclass fire rating - A1 Water repellent and vapour permeable Resists rot and mould
Q.. so the slip ties go in around 6m..But when the render goes on the outside skin of all those blocks does that render come to a stop at that point? so we effectively have a visible gap? (later gap filled with silicone)
Good informative TH-cam video as usual. With regards to thermal cavity wall insulation, I’ve never favoured AIRCRETE bl’wk being used to improve thermal values, as the inner cavity wall leaf is really for loadbearing requirements from floor & roof loads & certain beams. Therefore, a dense aggregate block will tend to perform better structurally than AIRCRETE block & with all the inherent fixing issues to AIRCRETE. The advancement of rigid foam PIR insulation boards these days have good thermal conductivity values & its common place to find boards with values of 0.022 W/m.K & 0.018 W/m.K. Furthermore, these boards can be used as nearly full fill boards (as per your video) rather than partial fill where a 50mm clear cavity was typically required, subject to your region’s exposure zone & wall finish. When you compare the U-value of an AIRCRETE block compared with modern PIR insulation boards, typically an increase of only 10mm thickness of PIR boards achieves a better U-value than the AIRCRETE block. Therefore, as the thermal performance is so much higher than AIRCRETE blocks, a slightly thicker insulation board with a dense inner leaf concrete aggregate block will still surpass the required the 0.28W/m2K U-value for Part L1B of the current building regulations & the build will be better structurally & cheaper for the client.
Hi Stephen You can get them from any proper builders merchant. Mine came from Selco. Remember to pick up the black sleeves for one end only. Often the ties and sleeves are not in one piece. I think they are about £1 each.
The enginnering bricks are below damp and under the steel beams. The fact brickwork at the front is there to match the panel on brickwork on the main house.
Lovely warm extension... however what bout rest of house! Can't beat 50mm cavity close cavity at plate level to form still air ... into existing older properties... might also save client a heap of wasted cash... though do you out of a job? Malcolm Perth Western Australia
Hi great video very informative,I am going to build my own single storey extension in block work,9.75 metres long so would you recommend expansion joint on both inside and outside leafs.Also do you recommend the hemlite blocks externally as I was thinking of using them for insulation and ease of weight reasons. Would you recommend the insulation you have used or 100mm rockwool which do you think is better.Thanks Lester
Hi, you could increase the thickness of the insulation if possible, thermal blocks are not as effective as actual insulation. But its to work out the cost as thermal blocks are generally more expensive than concrete blocks.
Where does the water go when it accumulates at the bottom of the cavity? It can't just drain away, continuous DPC should run through from inside leaf down and out to outside leaf with weep holes/vents to allow moisture to escape. Proper order.....
How much water do you think gets down there? A clear 150mm void beneath the dpc allows any moisture to sit there and soak into the ground through the blockwork. It happens in most cavity walls with no problem. Don't forget this is rendered. The water is more likely to be from the dew point.
The insulation is sized to go in between the ties which are in every other block course. There are some places around the windows where the ties are in every course. Here you need to push the wire through the insulation. It is easy to do.
Hi Stef. If you think about it the moisture migrating through from inside to out is going to hit the warm side and won't condense. It escapes as vapour. Once it is through it will hit the colder outer leaf of the cavity wall and that is the dew point where the vapour turns to water droplets and runs down the wall to the footings. The rest is soaked up by the wall and eventually evaporates as the wall warms up.
Hi Con Do you want brickwork tutorials? Rob Songer is good but we will try and add some but we can't ask our brickies to make a 'How To' Video they are interested in getting on.
Skill Builder thanks for getting back to me Rodger I know the videos you're on about I'm a bricklayer myself I don't like Rob's Technik you only beds out for one brick at a time. but for all that he leaves accident what behind them I just like to see other Bricklayers and their techniques love your videos keep up the good work Happy New Year
Just a question from the USA, when you render the walls( we call it stucco) do you put a metal expansion joint down the sides of the windows to keep control the cracks? I really like your videos, you have a great sense of humor.
We put what we call angle beads down the sides of the windows. They are metal or plastic. They are there to form crisp edges. The crack control is achieved with movement joints which run all the way up the wall.
Hi Roger! Could please explain the point of the expansion joint on the internal wall because the plaster board doesn't not expand or contract and it all gets skimmed. Thank you
Hi Viktor This is a very good question and you are right about the plasterboard. If you are doing a traditional plaster system you would have the expansion joint coming through but people don't like to see it so often it is placed behind a wall or door frame. In this case we are using dot and dab and the boards will be fixed with Geocel foam which allows the wall and plasterboard to move independently. If you are using dry wall adhesive (rock hard) then the wall will have dried out and shrunk before this has done so all the movement on that joint will have taken place. It is very unlikely to move after that. A lot of people don't bother carrying the movement joint through into the internal skin but if you do it by the book then you should do it.
![HOW TO BUILD A CAVITY WALL [Bricklaying for beginners e.p.14]](/img/n.gif)
You explained everything clearly , I’m a sixty six year old retired chippy and I love your channel and changes to the building good and bad as the years go ; thank you 👍🍺
I do like the subtle skills that come with time, like at 49 sec where the brickie throws a snot back on the mixing board without a second thought. Great video.
0:45 That was one of the greatest mortar spreads i have ever seen in my life. Craftsman.
roger, i could listen to you talk forever. keep up tthe good work matey.
Another great video, cheers Roger, you're always very informative and knowledgeable.
I look forward to your videos being released, keep up the great work!
Addicted to this series. Fantastic job guys, I'm learning a lot
Another great video. And thanks for mentioning the slip ties as they will be needed in a job I have planned.
yet another blinding vid from the SB library - thanks boys
Another great informative video. Thank you.
I work in development but mainly on the finance side. Though let me tell you, nothing makes me happier than a good bricky and his brickwork.
just found this channel and thanks for the details on expansion gaps that was so useful, many thanks and will be cramming in alot of these videos now :D
Great video as always. Good insight on property development and what to watch out for with these half a job builders.
Just come across your channel from this extension. Looks like you’ve got a decent gang. Cracking job. And skills. Credit dude
Nice to see the DPC bedded on properly mortar above and below many brickies dont do it like that Roger this could be a point you could raise in one of your videos
Does this make a big difference over just bedding on top of dpc? Ive only seen it that way and thought it seemed odd
@@handle1196 Dpc should always be bedded it is bad practice not to
Just came across your vids now on the extension..great vids. Love the knowledge dropping on the insulation and brickwork. Would love to learn more of these little details on building in future vids
Good night to all architecture students who are watching this vid
No bad thing
All looks quality work well done. Don’t like the full full insulation in cavity though? Yo can be the best bricklayer in the world, but trying to keep a 10 mm void clear of snots realistically is a big ask. You just can’t beat a clear two inch cavity; it’s there to do what it’s designed to do ... keep water OUT👍👍
Hi. Lots of great detail thank you keep on posting
Well done guys, a really interesting video.
Thank you Roger. Great video
I always check things before builders do something. But I trusted our architect/engineer when he provided the specification drawings. Once the footings were finished I learnt that now the building regs require 150mm cavity instead of 100mm. Our footings were done with 110mm cavity (103mm brick + 50mm residual cavity + 60mm PIR insulation + 100mm blocks). Now I wonder if the building inspectors would ask to break the footing and redo with 150mm cavity :(
Interesting how the methods are different in Poland. Double walls are very rare here. Most popular is to build a house from air concrete blocks and then put 20cm styrofoam outside and then put plaster with mesh inside out 4mm thick.
Nice work great detail
This guy really knows his craft. Would hire u in a heartbeat to do work on my house. In Scotland though, bad luck for me.
Packed with info, brilliant.
These videos are really helpful. 👍🏼
t & g is a nightmare to lay/place. i'm foil taping my joints to ensure its air sealed but have to cut little notches out of tongue to slide in the 20mm then fill with expanding foam when next layer goes in. tip - put loads of ties in the very first course to fully support boards and keep level
Hi Munkmeister
It is time-consuming I agree and stuffing 100mm Rockwool batts in is easier. Like your tip about placing loads of ties in the first course. We didn't and it rocks around. We just bashed the end of the board and the ties cut their own path. I thought about taping the joints but am not sure about the airtightness being that important. If the cavity is sealed there is very limited air movement in there.
@@SkillBuilder I have scrutinized many of your video's and if you are the foreman with the knowledge you have ,I would advise you to go back to college and retrain !
Thanks for the video, and the most important explication you give to us
I think you should tape the insulation to make the wall air free.
The joints on the foam boards should really be taped.
Water loves to wick by capillary action and even "defying" gravity and goes straight up
Over engineering
I wonder weather just square edge boards and taped with foil tape would just be as good.
Expansion joint.. Interesting how we tend to forget and then "rediscover" things. Ancient Inca ( Maya, Aztec ect ect) were using something like that. Basically, on top of granite blocs there were T carved out and when they connected two blocs it created double T which they were filling in with molten lead. This is also why these structures were so durable.
Genuinely amazing 😉
love your vids
Great videos, keep up the good work.
Have a word with the guy using the chisel. He needs to grind the curls off the top. They can be dangerous if they fly off. I know a guy that was blinded by one.
Good point for sure, you can often knock them off with a hammer
Tidy builders. Top job
Stopping the property breathing, is that a good idea? what about the condensation that these properties have been experiencing especially in the loft area?
Whose bright idea was it in the first place to full fill the cavity and now the ridiculous 150mm full fill?
Great videos
Thank you for the great video and invaluable insights. I have a question if using 50mm PIR in 100mm cavity (not T & G) do you use aluminum insulation tape to the joints between the pir sheets? also how do you get the PIR sheet to stick to the inside wall?
Yes use foil tape and fit those red plastic discs to hold the slabs to the inner skin.
@@SkillBuilder thanks for the quick reply, much appreciated
Nice one Roger! Informative, even fascinating. Luvit!
Gd work,if you put in xtra wallties,on the first 2 sections of thermboard insulation,it stops d board from buckling,and maintains a good tight fit up the wall,
Is there a way to use the normal 90mm×1200mm×450mm PIR boards (without tongue and groove edge) in a fully filled cavity like this? Any alternative way to close the gaps with tape etc?
Whats the difference between using wool vs pir boards. Love your videos btw
I am loving the work and information you are providing and it is clear that the damp proof membrane and insulation work hand in hand, but what I cannot get my head around is how the break is done when you have a door space and the wall seems to connect the outside and inside together
John Fithian-Franks cavity closers are used which comprise a layer of insulation and a damp proof layer.
@@letsgocamping88 Thanks for that, I am considering a pair of doors to open onto by back garden but I did not want to create a way that damp could bridge the gap and get into the house.
Older houses did used to close the cavity with brickwork. My window sills and reveals are this way. Acts as you suspected as a thermal bridge. I’ll be looking to insert some sort of cavity closer or over board with insulation in the future.
Hi Rog, if there's a tongue & groove system - How do the wall ties fit? Thanks for the vid.
The wall ties just poke through on the T&G joints.
@@SkillBuilder Appreciate it Rog! Thanks for getting back to me
@5:37, you can use spray foam as well, just make a hole and start pumping in...
Superb
Please make a video how to keep old Victorian single brick houses, damp free!!!
WiseEyes plenty of air movement / ventilation. Pointing in good shape. Leaving a gap between building and any garden wall or fence post.
Sir. In places where the climate is hot all year round, what do we need to do for the walls? Do you need ventilation or use insulation?
Hello again Roger.
Just found your videos, Got a Good Tip for you when you build one skin of the cavity which ever you put the ties in .We put mf 7cieling Ali channel on the cavity ties To catch the Scott’s .helps with a Clean cavity. Cheers speak soon .jimmy
Ps I also live in sw London
Roger ,why is there a brick part in the bock inside wall?
Brilliant
thanks
The metal ties create cold bridging from outside in even with that insulation. Are there plastic options that have similar properties?
How do you get the insulation into the cavity with the wall ties between the cavity?
Very interesting video well done. I would like to know how the relationship between the cavity wall ties and the rigid cavity wall insulation works. Would I be right in thinking the insulation is cut to suit the wall ties? If so that must be quite a messy process as I am sure the cavity wall ties are supposed to be staggered vertically and horizontally. It must cause the bricklayer a bit of a headache if that is the case.
The insulation boards are sized to work with the wall ties. No cutting required and in some places we just push through
On corners do you use damp proof up corners, spec says to but i dont see why its needed.
Good video
Good stuff, all neat and careful, would query the wall ties not being staggered though.
Hi Lisa
Good bit of observation there and on some points they may be in vertical lines but I think you may be looking at either side of the pier and movement joint where they are in straight line on every course. The others are randomly staggered but they are every other course and laid in the block not under the perp because is hold them down better. We put one in every course either side of the windows and doors. At those points, it is tricky with that insulation because it is easier to push them through afterwards and point up rather than try and push the insulation over the ties. We used some Tiger ties at some points just to make life easier.
Actually look at 52 seconds, shoots you're statement to bits, 4:40, up pillar, only one wall tie on each course, don't get me wrong, really good work, inspectors and C of Works would never accept that in this area.
Sorry Lisa
Call me thick but I don't completely understand the point you are making. You can see Mark pushing wall ties through the insulation on the edges of the window openings so they are in every block course around openings. Elsewhere they are spaced closer than 900mm on every other block course. At the movement joints they are in every block course. I am happy that you are taking the trouble to comment but I am struggling to see what is wrong or what the building control inspector could object to.
that perp joint at 9:05
dope
Hi Roger, great video. How does external insulated rendered cladding work with the cavity? Does it just mean no insulation is needed or would it leave a cold spot on the internal walls? Thanks
Hi Nick
I have never seen EWI used with a cavity wall. It is mostly a way of insulating houses with solid walls and it gets a bit of bad press because there are often cold bridging issues. Basically, the difference between the insulated wall and the odd bits around the eaves or windows is so marked that the airborne moisture in the otherwise warm house hits that cold spot and condenses. It is a really good way of insulating because it leaves the thermal mass of brickwork on the inside so it gets heated but those odd areas where the insulation can't be applied is a huge drawback.
Ah ok. Will nail that one on the head. Thanks again.
@@nickwalton8864 there's ways around those issues mentioned. You can get insulated sills passivesills.com/ and use a couple of thermal courses at the eaves and also at ground floor level which means zero thermal cold bridging anywhere. I've drawn up A rated houses using 200mm EWI and 215mm block work and its my preferred construction method by far. Some more info. passivehouseplus.ie/magazine/guides/the-ph-guide-to-external-insulation
Useful info!
Quality brickie!
Looking forward to part 5. How much floor area will this extention add in m2. Also roughly how much will it cost?
It is 24 sq mtrs per floor and there is a half cellar. Cost is going to be around £75,000
Skill Builder does that include VAT?
Ah yes the vat is extra
Problem is getting a good builder who will install it correctly too many couldn't careless and you'd never know till years later (when you've got damp issues) that theyd installed it incorrectly.
Don't like the idea of the insulation with only a small cavity. The wall tie penetrates the whole wall and the drip on the tie becomes redundant. Even though you have clips which should stop the water ingress, its still possible with enough water for it to track. Plus in general if the outside block/brickwork is slightly higher than the inside the potential for tracking get exacerbated. BTW it's a movement joint not a expansion joint, on any plan its marked as MJ.
Other than that great vid and quality bricky.
Looopy2u
You are right expansion joint is not the right term because it is as much about shrinkage as the materials dry out as any expansion. There wasn't one on our drawing and I find this is often the case.
As for the water ingress you have a point but the way the insulation sits around the ties means that very little would get past and then it has to soak through the mortar to appear as damp. That said this is a very exposed gable end and I will be watching to see if there is anything coming in.
Probably you have nothing to worry about, just a concern I have with this kind of close cavity system. Plus there are a lot of builders out there that are not at your standard so it would be easy for them to hide any high block work that would result in backward running ties. Maybe I've worked on too many 50mm+ cavity systems :D Hard to teach an old dog new tricks!
in the us its called expansion joint
Funnily enough in roads and bridges the U.K term is also expansion joint but in houses and lesser structures they talk about a movement joint.
Just checking on the dpm. Just 100mm on each skin? No tray or 300mm across brick and block work?
Thanks
Normally the dpcs are on each skin but if you have water that needs to be directed to the outside then a wider stepped down dpc is used. This happens over lintels etc
Top man
I went from living in a old brick house with no insulation to a modern one with foam...I will never go back to living in an old house again...I hope.
Nice !
Thin joint mortar will reduce thermal bridging in lightweight blocks. Cavity can't be filled with mineral wool insulation as it will become damp and start to rot. To many thermal bridges including wall ties.
Cavities are filled with mineral wool all the time in the U.K . It is glass or rock and therefore won't rot. They claim that damp won't cross it.
Didn't you hear about billion of pound worth insurance claims arising from mineral wool used in cavity. It is breathable and therefore can accumulate moisture that travels true internal leaf, depending on pressure differences and damages structures organic materials.
Mineral wool is usable as external wall insulation were it can dry or internally were it's protected from moisture, but not in cavity.
Insulation Cavity Batt
ROCKWOOL Thermal Cavity Batts are a semi-rigid full fill insulation solution for masonry cavity wall construction, suitable for use in extensions. It is easy to handle and install and provides a close fit against brick and blockwork. The batts are non-combustible and water repellent, yet vapour permeable.
BBA certified for all exposure zones
Acts as a cavity barrier
Prevents water transmission from the outer to inner leaf
Highest Euroclass fire rating - A1
Water repellent and vapour permeable
Resists rot and mould
Love it
Is this wall cladding fire proof? John Hankin
what cladding are you talking about?
Good explanation 👍
Excellent videos , thanks
Q.. so the slip ties go in around 6m..But when the render goes on the outside skin of all those blocks does that render come to a stop at that point? so we effectively have a visible gap? (later gap filled with silicone)
The joint is filled with a foam and yes you can see it
Genious
Great tips. Lookalike of Anthony Hopkins
Ho did do they get the insulation in between when the brick-ties are in place?
It works out every other block course. That is how it is designed so the ties line up with the joints in the boards or batts
Good informative TH-cam video as usual. With regards to thermal cavity wall insulation, I’ve never favoured AIRCRETE bl’wk being used to improve thermal values, as the inner cavity wall leaf is really for loadbearing requirements from floor & roof loads & certain beams. Therefore, a dense aggregate block will tend to perform better structurally than AIRCRETE block & with all the inherent fixing issues to AIRCRETE.
The advancement of rigid foam PIR insulation boards these days have good thermal conductivity values & its common place to find boards with values of 0.022 W/m.K & 0.018 W/m.K. Furthermore, these boards can be used as nearly full fill boards (as per your video) rather than partial fill where a 50mm clear cavity was typically required, subject to your region’s exposure zone & wall finish.
When you compare the U-value of an AIRCRETE block compared with modern PIR insulation boards, typically an increase of only 10mm thickness of PIR boards achieves a better U-value than the AIRCRETE block. Therefore, as the thermal performance is so much higher than AIRCRETE blocks, a slightly thicker insulation board with a dense inner leaf concrete aggregate block will still surpass the required the 0.28W/m2K U-value for Part L1B of the current building regulations & the build will be better structurally & cheaper for the client.
❤
Hi Roger , those "Slip-ties" ,how much are they ?? who sells them ? Got any links #... Love your videos, very informative.
Hi Stephen
You can get them from any proper builders merchant. Mine came from Selco. Remember to pick up the black sleeves for one end only. Often the ties and sleeves are not in one piece. I think they are about £1 each.
Need my extension done this year
how do you render over the expansion joint on the outside? wouldn't that crack?
Expansion bead.
Just put two beads side by side then render over, clear the cement from the gap the. Squeeze construction silicone into joint.
How are you going to render over painted brick?
We are not and it is one of those things I would only do if I could get some of the paint off and rake out the mortar to give a good key.
Why do you use traditional red bricks in some spots and the engineered bricks in others
The enginnering bricks are below damp and under the steel beams. The fact brickwork at the front is there to match the panel on brickwork on the main house.
Have a look at this Full Renovation video: th-cam.com/video/i7SQuXlgWiY/w-d-xo.html
Whilst saying how important the tongue and groove is, in the background the insulation has the tongue and groove cut off 🙂
Where does that happen? Give us a timecode
Lovely warm extension... however what bout rest of house! Can't beat 50mm cavity close cavity at plate level to form still air ... into existing older properties... might also save client a heap of wasted cash... though do you out of a job? Malcolm Perth Western Australia
Hi great video very informative,I am going to build my own single storey extension in block work,9.75 metres long so would you recommend expansion joint on both inside and outside leafs.Also do you recommend the hemlite blocks externally as I was thinking of using them for insulation and ease of weight reasons. Would you recommend the insulation you have used or 100mm rockwool which do you think is better.Thanks Lester
Hi, you could increase the thickness of the insulation if possible, thermal blocks are not as effective as actual insulation. But its to work out the cost as thermal blocks are generally more expensive than concrete blocks.
Where does the water go when it accumulates at the bottom of the cavity? It can't just drain away, continuous DPC should run through from inside leaf down and out to outside leaf with weep holes/vents to allow moisture to escape. Proper order.....
How much water do you think gets down there?
A clear 150mm void beneath the dpc allows any moisture to sit there and soak into the ground through the blockwork. It happens in most cavity walls with no problem. Don't forget this is rendered. The water is more likely to be from the dew point.
That looks like Phil Turner on the bricks
Who is Phil Turner? Never come across him.
Google him and tell me that doesn’t look like him :)
ok so I have seen him now and who does he look like? There are two brickies.
1.27m into the video, pretty close resemblance
Yep same tribe for sure. Those Vikings got about
How do you insert the insulation with wall ties in the way?
The insulation is sized to go in between the ties which are in every other block course. There are some places around the windows where the ties are in every course. Here you need to push the wire through the insulation. It is easy to do.
I thought that silver foil insulation is condensating?
Hi Stef. If you think about it the moisture migrating through from inside to out is going to hit the warm side and won't condense. It escapes as vapour. Once it is through it will hit the colder outer leaf of the cavity wall and that is the dew point where the vapour turns to water droplets and runs down the wall to the footings. The rest is soaked up by the wall and eventually evaporates as the wall warms up.
I’m just going off Norfolk building control … they won’t allow silver foil backed insulation without a vapour barrier
How could someone living in a house like that afford a builder of his quality?
I work for free. I never charge any money.
@@SkillBuilder ah, that’ll be all the TH-cam money 💰
I dont know why they dont make 80 mil insulation
why don't you Joint up any blockwork?
it is not face work. It is all to be rendered with sand and cement.
Mr Brightside h
hi Rodger could you add in some Block laying bricklaying videos please
Hi Con
Do you want brickwork tutorials? Rob Songer is good but we will try and add some but we can't ask our brickies to make a 'How To' Video they are interested in getting on.
Skill Builder thanks for getting back to me Rodger I know the videos you're on about I'm a bricklayer myself I don't like Rob's Technik you only beds out for one brick at a time. but for all that he leaves accident what behind them I just like to see other Bricklayers and their techniques love your videos keep up the good work Happy New Year
Thanks Con . That is an interesting point you make. We will try and line something up by way of a master class. We have some more projects underway.
Just a question from the USA, when you render the walls( we call it stucco) do you put a metal expansion joint down the sides of the windows to keep control the cracks? I really like your videos, you have a great sense of humor.
We put what we call angle beads down the sides of the windows. They are metal or plastic. They are there to form crisp edges. The crack control is achieved with movement joints which run all the way up the wall.
Don’t need expansion joint if you are working in tradition lime build.
True but we aren't. Building with hydraulic lime is too slow for the modern builder
Hi Roger!
Could please explain the point of the expansion joint on the internal wall because the plaster board doesn't not expand or contract and it all gets skimmed.
Thank you
Hi Viktor
This is a very good question and you are right about the plasterboard. If you are doing a traditional plaster system you would have the expansion joint coming through but people don't like to see it so often it is placed behind a wall or door frame. In this case we are using dot and dab and the boards will be fixed with Geocel foam which allows the wall and plasterboard to move independently. If you are using dry wall adhesive (rock hard) then the wall will have dried out and shrunk before this has done so all the movement on that joint will have taken place. It is very unlikely to move after that. A lot of people don't bother carrying the movement joint through into the internal skin but if you do it by the book then you should do it.