Insulating a Solid wall with Lime Hemp Plaster
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- เผยแพร่เมื่อ 19 ต.ค. 2024
- We decided to use lime hemp plaster on the external walls of the house, this was so we could restore the house walls to be breathable as intended. This will hopefully reduce the risk of damp and condensation as well as adding an amount of insulation level to the walls.
The lime hemp was sourced from Ty Mawr in Wales and was delivered as a ready mixed tonne bag. Link below to their site and products.
www.lime.org.uk/Ty Mawr
Music by "PIONEERS" by Jason Shaw (audionautix.com...)
That looks a great job, it's good to see someone doing it properly. My customers are constantly asking why their 100+ year old houses are damp, I always tell them the same, modern materials used in the wrong way. Gypsum and cement pointing cause so many problems.
I'm sure you'll have hear of Keim mineral paints by now, but if not look them up. Acts like modern paint but 100% breathable, and not that expensive. And you don't need 10s of coats as with limewash, and you can have almost any colour.
Thanks for the comment. Yes it is such a misunderstanding, we have so many houses around here where everything has been skimmed in gypsum and vinyl paint, such a shame especially when people are spending £££ on damp treatments unnecessarily. We ended up using Earthborns claypaint but their new emulsions look good too.
Funny just quoting a barn conversion job and the architect said I was demonising modern methods because I refused to use PIR insulation in a 400 year old structure I instead offered Hemp and wool that met their U rating but they told the client I would not meat fire regs, funny how the PIR they recommended is not available because it’s failed an independent fire testing. Natural materials and breathable paints all the way.
Great video and well done answering everyone's questions.
Great videos...very helpful! I'm buying a large Victorian terrace which I plan to renovate myself. Do you think I would need to lime plaster the adjoining internal walls of the terrace or do you think I could get away with just doing the front and rear internal walls to help the house breath? Thanks!
Remove all gypsum and start again all walls with lime
I would not worry as much about the shared walls as I doubt the neighbors will have left the walls breathable their side! Unless you had any bad damp issues at the base of them I would be tempted to just skim them in plaster and focus your efforts on using Lime front and back. Does the property still have lime mortar or has it been re pointed?
Great video, and looks good. Haven't seen the rough coat applied with fingers before, although looks much thicker and more clay like in texture than the coarse stuff I have used. Did you experience any cracking with your final lime skim? I wanted to say that it is sometimes important to use lime plaster on internal walls especially those shared with a neighbour for the very reason you suggest not to; that the other side will likely be Gypsum. Your house may still have a good DPM, however in many older houses it is likely to be ineffective or depending on the age non existent, therefore rising damp will need to exit somewhere...better your side through lime than blowing gypsum plaster on either side.
85robin1
Yeah that makes sense. We are detached so haven't really thought too much about party walls. In an ideal world I would have done everything that way however with time and budget it made sense to you gypsum over the internal walls and ceiling as they are mostly stud anyway. No cracking whatsoever, really impressed, plenty of settling cracks in the gypsum but not a thing in the lime after a year. TRC
TheRestorationCouple Yes the cost of lime soon adds up doesn't it! But then you don't have to redo everything when the gypsum fails in a few years. I have used gypsum on ceilings quite happily in older buildings, as you say there is no benefit to using lime here aside from a small aesthetic of keeping ultra true to the original. Good that it didn't crack, how long did you leave the coat below to dry? And did you wet it down before finishing went on?
85robin1 We did Lime hemp in a couple of coats with 2-3 weeks between and then maybe 2 weeks before finish. Our plasterer did the final skim but think we sprayed with water as we went. May well do the cellar in the same way, or just lime wash stone walls for now.
nice. That would be brilliant over AAC blocks for new construction. wonder how much R-value this adds?
This is truly remarkable.
Very interesting-I am thinking of restoring a mid 18th century chapel and this seems like a great way to insulate the walls-
Do you know how much the materials cost per m2? Are you using just hemp straw water and lime?
Looks great
Hi, great video, I have had a dilemma in that I bought a house for my family, Victorian mid terraced, 1900 build, the property was allowed to get into disrepair and empty for a while. I have since stripped every wall back to brick, removed all flooring ground floor and all ceilings, in effect the house is a shell. I have been told I have rising damp, which is not noticeable on the brick work only the metre that they use. I am replacing all the sash windows to new timber double glazed, and a number of plasterers have suggested 20mm cement render then 5mm skim plaster for all walls, then by others been told to plasterboard dot and dab, concerned on renovating the entire house then have issues, so would you recommend hemp for front and back and cement and skim for internal walls, also on internal wall there are couple of chimneys what would you use on them?
Not sure whether to do damp proofing treatment since I have already stripped back to brick anyway.
Tricky to say. It depends on how breathable the external is, what pointing, render, paint, bare brick, etc. There are other breathable backing plasters you could look at like limelite. If you have the house gutted, are you insulating walls? If so now is the time!
hi. first of all im waching all of your videos they are amazing!!!
can finish coat be layered with lime nhl 3.5 powder? if yes what is the ratio mix? many thks
Very nice job.. did the hemp lime plaster make a noticeable difference to the relative humidity and warmth in the room?
Hard to quantify temp but not cold to touch like some of the other walls. As far as moisture, no sign of any damp in the walls now whereas the old plaster had marks and discoloring.
Hi there, thanks for the video - really helpful! We are wanting to hemp and lime plaster our inside walls and have so far chipped off all the plaster/concrete and got the walls back to stone inside (house built early 1800s). The house has lots of damp so we are intending to make all the walls breathable.
We were wondering whether you think we need to strip off all the external concrete render first though, before we do our internal plastering? We are planning to take off the outside concrete at some point in the next year, but would ideally like to leave it til next Spring and focus on plastering the inside now...
What do you think? We'd really appreciate yr thoughts. Thanks!
The walls will not be breathable until the render is removed however there is no reason why you could not sort the inside out first. There is a chance that you may still see some existing moisture in the stonework make its way through as it breaths through the new plaster as it can't escape out. Providing you use breathable paints that is no problem, we just noted that some areas of paint dried slower. You will need to ensure that when you re point the stone outside that its all lime mortar.
thanks so much guys - where did you get your hemp/lime from?
Jubilee Place No problem.
Ty Mawr over in Wales. Very helpful and quick delivery.
what would you think about. battening an external wall. mineral wool/rock wool inbetween. then lath and plaster using lime mortar. is this stupid idea or would it make sense?
Hi @therestorationcouple. I have hygroscopic salts around my chimney breast in my Victorian terrace. Would you say that following your method of lime plastering could solve the issue of the salts 'blooming' or do you think this would happen if I simply just applied lime plaster over it (with the damp having dried out as much as possible of course)
What mix was it? Sharp or soft sand?
Hi guys, great content. I hope you have time to answer my question. I have wattle and daub wall with lime plaster render, the plaster is blown and crumbling, the wall is situated in the upstairs hallway where the banister is, an internal wall. I was thinking of treating it with bonding, fibre glass mesh to fix the broken areas then apply multi-finish to skim coat the entire area, as bonding and multi finish plaster in not really breathable material to use. Is it important to have interior walls breathable? 😊
Not if it’s an internal dividing wall, more of an issue on the external walls.
What was the Final Top coat please?
What have you used to skim the walls? I'm finding it hard to find something smooth to skim which is also breathable and won't compromise the lime plaster.
Also, was the last coat the fine hemp plaster, and the base coat coarse?
You've got a really nice channel!
First wall we used a traditional lime finishing plaster skim over the medium lime hemp, (we did two coats of medium as recommended by the supplier). You can finish with a fine hemp mix to leave a slightly textured surface and even unpainted apparently looks nice albeit slightly rustic. In another room we used high impact lime lite, although not lime as such it is very easy to use, super breathable and a very durable finish. Hope that helps. TRC
+TheRestorationCouple how did you find the (tarmac?)high impact lime lite? Where would that product be best used? does it work in a way similar to hyd/putty lime plaster. What would you recommend for a 1820's period kitchen semi below ground in some walls (terrace/neighbour house built higher on one wall) It has been taken back to bare lime plaster/masonry in most places. Kind regards Luke
Hi Luke, It goes on much like gypsum, in that it is a similar mix and does not need much attention once applied. Our plasterer did the final skim and apart from a longer drying time and a very slightly textured surface it ends up the same a s the adjacent gypsum skimmed walls and ceiling. It is designed for what you described and will remain breathable. It is of course not the 'traditional' route however it is certainly still a conservation route and better than trying to tank and seal walls which just causes other issues. We used the renovation plaster for repair work where lime plaster had come off the stone in other rooms. Hope that helps. TRC
Hi , what coverage rates did you get with the lime bags?
Very pleasing to watch.
Q: how much lime mortar did you apply before starting your plastering ? Did you apply it just in the large gaps or also in the smaller crevices ?
Whole thing had minimum of 30mm or so with more in the deeper gaps. Then skimmed over after.
Hi Tim, I'm currently renovating a 1900 Victorian property in South Wales. I'm looking to repair and replace the old blown and cracked plaster on both external and internal walls.
What lime hemp plaster did you use, as in hydraulic vs non hydraulic, medium/fine etc
I'm looking on doing the scratch/float coats myself and getting a professional for the final skim
Any advice would be greatly appreciated
Hi. I think the hemp was medium. The guys at Ty Mawr (wrong spelling) were really helpful and advised us. It comes pre mixed wet in a ton bag so not suite on the makeup exactly. Hope that helps.
The Restoration Couple thanks for the advice, they seem to only be 30 minutes up the road from me so will have a good chat with them
hi, what did you use on the corners?
How is this insulation? It's the same as your other upload?
Our C19 Victorian cottage has been dry lined in two rooms and the lower parts of the underlying solid walls have crumbled quite badly and salts have crystalised out in the brickwork. We want to restore with lime plaster. What should we do about the salts and spalled brickwork?
Ideally you need to remove drywall and let the salts some through over time before plastering. They simply brush off usually. Is it still lime mortar pointing outside? As it would be helpful for you to know the source of the salts, i.e cement, chimney, etc. In one or two spots we had some salts coming through the lime hemp, it lasted a month or so, and just dusted off. Nothing since then. TRC
Can you lime plaster over thermal boards?
Tim, if you don't mind me asking, how much was this lime plaster to the wall you are showing? I am plastering my country cottage soon so it would be great to know as was planning on gypsum skim until I saw your video!
Hi, £260 for the 100kg ready mixed lime hemp which we did ourselves and then maybe £100 of materials for the top coat. This was skimmed by the plasterer however if you like a more rustic finish the lime hemp can be left fairly smooth on it's own. Even if you decide against lime hemp, please look at using breathable plasters as gypsum and solid walls are not best friends in the long run! :-)
Thanks Tim. We have a party wall to the right and are building a side extension to the left. I assume I only need to use lime plaster to repair/skim the front and rear external facing walls? Can any plasterer use lime or is it only specialists in this area?
A purist would suggest still using lime as there is still there risk of moisture from the solid wall base. However we did use gypsum on our internal walls. Front and rear best to use breathable. If already lime plaster then patch with a breathable repair plaster skim, if back to stonework then more options. The modern breathable plasters will be familiar to most plasterers, only traditional lime will be best suited to expert, IMO.
@@TheRestorationCouple what is the materials/ingredients for the top coat please? Thanks so much
Hi there we are facing the same job as a the old plaster is damp on all outer walls. Is the final skim just made from normal gypsum?
No it’s a breathable lime based skim then finished with clay paints or breathable emulsions.
@@TheRestorationCouple thanks for the reply 👍
Hi guys, firstly lovely job on the walls. Looks like your doing everything the right way to hopefully avoid damp issues down the line.
Can I ask, did you install any kind of fibreboard or similar insulation on the interior walls, or just rendered and washed? I'm hopefully going to embarking on a similar (solid walled) project soon and was wandering what is the done thing if you wish to improve the U values whilst still allowing breathability through the walls. Cheers :)
Thanks. We contemplated a full internal wall insulation approach with a fibre based board however the costs were pretty high even if diy and it would have meant a lot of work to get it continuous through all the levels, then there is still some condensation risk and cold bridging of joists etc. therefore we decided to insulate floors loft and new windows and focus what remaining budget we have on renewable energy. So yes the heating demand is fairly high however at least we have a sustainable way of heating and energy. In an ideal world we would do both however for now we just have to do what we can. TRC
P.s if we did not have nice stonework on the outside I would have most definitely wrapped the whole house with external insulation and rendered. Much better approach than internal if it is possible.
That's interesting that you mention the costs being high. I haven't done a proper costing but was considering the possibility of insulating just the external (front and rear) walls as its a mid terrace, but like yours has nice stone on the outside so external insulation is not an option. Presumably your log burner keeps the chill off nicely though ;)
Yes it's a tough one to decide on. Internal insulation would have caused so much disruption and blown our whole budget, however £250 a month on heating is hardly a solution either! It's the breathable insulation which pushed the price up and there is no point doing it if you don't do joists, window reveals, chimney breasts, etc, then you have the additional issue of loosing room space. We have just spent the first week with our new biomass boiler so it's quite toasty now!
Good work! However you cannot speak of insulation when the layers of hemp/lime is that thin. The U value is ridiculous so is the R value. However that texture will give a warm feel which will increase the confort.
+ririshow I agree, it may be slightly better than the same depth of original lime plaster however does not substitute internally insulating at all. Our main priority was keeping it breathable and as a bonus it is not cold to the touch.
Great Video, I am doing something similar with my 19th century cottage, just wondering did you install any vents in the external wall? I'm tempted to knock a hole through just to give the room some additional ventilation, thanks
There are sub floor vents to outside under the timber floors but nothing anywhere else. Most old properties are 'ventilated' enough as they tend to be leaky anyway. I would not think it necessary and rely on windows for if/when you need more airflow.
hi how is your experience with the wick now in 2019. we we try the same with our wall and want to hear how it has been.
Its all been good and all walls nice and dry. There is a degree of insulation but really only if you were to go much thicker.
Hi. I have been trying to find out more info on this . I have a Scottish house mad of flag stone . Walls are 3 feet thick. Where can I find more info. Is it a good insulater?
Not a thermal insulator at this thickness really but does help. You woudl need to build it up quiet a bit to be effective. There are breatbale insulation boards which would be much more effective. Lime hemp company was Ty-mawr Lime.
Is it possible to you use this over an already plastered wall albeit roughly plastered ?
Not much benefit unless already breathable and even so a like finishing plaster more suited. If insulating then breathable products like wool board can be used.
I have thick schist walls covered in some kind of rough plaster or mortar. I wondered if I put lime hemp plaster over that whether it would provide some insulation as well as a better finish. Heat does drift out of schist despite thickness. @@TheRestorationCouple
Have you found that the lime/hemp plaster actually provides some insulation? I have an old stone cottage with 2 foot thick walls and want to maintain the breathability but not have huge heating bills!!
There is a small thermal benefit and the walls certainly don’t feel cold to touch like the other traditional line walls. That said you would need much thicker layers to actually ‘insulate’ or a breathable insulation such as wood wool boards or similar.
Phil, I work with hemplime a lot, and can confirm that this plaster brings only a slight thermal benefit (as Tim has said). However, hemplime is a bit special, in that it has some thermal mass to store a bit of heat, good thermal resistance to slow the movement of that heat, and the ability to regulate humidity and capture excess & hold on to it until your space is drier - all of which helps your space 'feel' warmer. If you have room to lose 100mm on your external walls (& walls that have corridors the other side) then you'd benefit more from putting in 100mm of hemplime and finishing off with a clay plaster - the clay is a better thermal mass layer and gives the best performance for buffering humidity. I've done this in a Victorian terrace in Bristol and the impact on the place is immense.
HI, was a 100kg enough to to cover that area ? 1st and 2nd coat.
Thanks and great vids and very helpful
1000kg, or at least a full builders dumpy bag, it comes ready mixed and wet so very heavy.
Hi,can you tell me what grade of hemp shiv did you use on the walls
+Richard Fleming Medium
can you tell what mix you started with on the walls initially after preparing the walls
+Richard Fleming it is a premixed wet mix delivered in a bulk bag. We used ty mawr lime.
Thanks!
In the fire place case i will leave the visible bricks on the top just paint them with stone varnish.
We ended up doing that in the kitchen and a couple other rooms we left the side bricks as well and lime washed them. Originally they would have all been hidden behind the cast iron surrounds however I do like a bit of exposed brickwork. TRC
Nice. Some times looks like magic to uncover the old times job, especially in old houses.
Wish u were in USA
Philadelphia Pa
Are you putting sbr first?
No thermal value gained by using hemp plaster it is only lime NHL2 or 3.5 with hemp fibres over priced mortar, get equally as good results using appropriate hydraulic lime, with good quality coarse sand and well fibered with hair or sisal. Or use premixed lime mortar with salt inhibitor added. More expensive but no fear of efflorescent salts, finish with putty lime 2-1 silver sand or premixed finish
Interestingly video.... But your electrical wiring should not be running horizontally. Naughty!
can i use cement instead of lime?
You could but it would not be breathable so pointless in this situation.
use a concrete chain saw and fit a plastic damp proof course right through the walls in 1m sections and overlap. Water fed no dust best possible solution. Do the same with internal walls 8mm cut so no problem with movement if re pointed properly in 1m sections with gun. Cuts like butter . Diy job £2000 for machine sell it on when done. Don't buy the cheap chains . £300 each
Not expensive as it will be a proper cure for rising damp. Penetrating damp, point outside brick work, ventilate house every day for 2 hours open a few windows to get the draft through, morning best before heating goes on. fit proper water covering cowls to chimney to prevent rain getting down the chimney and open up closed off fireplaces. natural ventilation. Use Lime wash and lime render after removing waterproof render or none porous painted render. as it keeps condensation in walls and stops the house from breathing vent the tumble dryer outside. Fix the gutters. Clean out the drain traps. Dig a french drain around the hose and fill with large pebble. Let the sun see the walls remove trees etc that block the sun. Lower soil levels that are above floor level. If you have green mold it's not rising damp as the salts in the ground water rising up from the ground would prevent the growth of mold. Green/ black mold is penetrating damp or usually just condensation from lack of ventilation. Phil
+phil price Thanks for the comment. Agree with you on most points, however it would be an absoloute last resort to start messing round with plastic in an old building. Solid walls have stood dry for hundreds of years, it is just simply the use of gypsum and modern paints which cause all the issues recently. The lime plaster and breathable paints sorted everything here and also deals with penetrating moisture and condensation which could cause issues anywhere up the wall, something a dpc would not do. With gravel filled channel/french drain and lime mortar and plaster there should not be the need for fitting damp proof course. Just the tarmac driveway the neighbors have against our wall to sort now! :-(
looks like you were doing internal not external , wrong video or wrong title ?
bhhardgr01 no this is an external wall of the house. I am not aware if lime hemp can be used 'externally' but this is how we kept our external walls breathable.
Would you guys please speak ENGLISH.... 😳... jk.. actually wondering if there is an USA 🇺🇸 equivalent for this product? Curious about the r value when using it as an insulator.. thinking of building a stone house that can breath... don’t want to wrap it In styrofoam ya know?
Thanks..
Not much at this thickness. Wood wool boards inside stone finished in lime is a good breathable option.