How Not to Plasterboard a Wall : Mould

10 years ago my kitchen walls were dot and dabbed - I'm going to explain why this was a bad idea, what insulated plasterboard you can use and how I'm going to insulate my kitchen walls.
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0:00 Introduction
0:42 Project Recap
1:38 Dangers of Dot and Dab
5:14 External Insulation
6:34 Internal Insulation
9:34 My New Strategy
11:45 Subscribe to Me!
USEFUL LINKS
- u value calculator bit.ly/3FGDSFN
- Building Regs Part L bit.ly/3mR8wp1
- Building Control Guidance Note 24 (renovation/ replacement definitions) bit.ly/3ZKa0Qy
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TODAY'S TOOLKIT:
- Ubakus U Value Calculator www.ubakus.de/u-wert-rechner/?
- Gapotape www.gapogroup.com/
- Ecotherm U Value Calculator bit.ly/3LR6mjO
- Kingspan U Value Calculator bit.ly/3LSm3r9
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#plasterboard #insulation #mould

[@CharlieDIYte]

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[@justoneofthesheep]

I am currently renovating my new first home and I need to do this to my entire house (external solid walls) Just wondering, did you need to get Building regulations approval to do this ? I'm a little confused where I stand with this. I have to do attic, walls and insulate under the raised floor.

[@arekarek1991]

I wonder if you have secured/ painted external walls. To be honest, I wouldn't go for that internal installation. Better would be external for longer run.

[@broadcasturdad]

What's important to me from this video is you have taken the time to really think about the insulation - which I find hard to do with work consuming my life. Thank you for the research

[@mrjh8467]

Eager to see how you achieve this. I am going through a renovation myself and we have decided against internal wall insulation due to several factors. and will therefore try to attempt external insulation in the future. I spent ages reading about how to insulate, and even airtightness, and too many approaches out there to say the least. It was too confusing and tradespeople did not help.

[@burnsironwork]

I built a two storey extension as a granny annex in 2003 using 40mm laminate plasterboard dob and dabbed onto 9" solid block work. I recently put new doors and windows in and uncovered a lot of the original wall surface. Not a hint of mould or condensation. External walls are rendered pebbledash. I am now doing the same to the main house external walls as i replace the old leaded light windows. If you try and consider all the issues you come to the conclusion its not worth it bearing in mind the cost and no one can get give a definite way to do it. however I need to be warmer as i get older in the winter. This time I am using adhesive foam which almost removes any gap behind the insulation as it needs perfect contact (keep pressure applied for half-hour plus across the whole board with temporary wood support and of course mechanical fixings). We do intend to open windows as much as possible to reduce humidity issues. in 10 years time I'll let you know if it worked!

[@robn749]

Thank you so much for sharing your experiences Charlie, it really is invaluable. I have a similar set of circumstances so it will be really interesting to learn how you get on with your approach. Best of luck with it all.

[@jonwilmot5331]

Great video Charlie, I've been getting involved in external and some internal insulation, I have solid walls and have researched this complicated subject, I have used alutrix vapour barrier and a combination of foam fixing and insulated plasterboard. you can end up chasing cold bridges until the cows come home . Somewhere the vapour barrier has to be breached. As you rightly say, ventilation is essential as moisture will build up eventually. Interestingly I ripped down 4mm conti board pinned to batten on my dining room walls and found the external walls bone dry. Unluckily my lead roof laid 20 years ago on a warm roof where no barrier was installed erupted and dissolved to white dust. You live and learn.

[@andyc972]

Thanks Charlie, as always, an open and honest debate covering pitfalls, alternative opinions, ideal solutions and then the rationale of the chosen compromise ! Some great information in this on a subject that is a minefield !

[@CharlieDIYte]

Thanks Andy. You're right it is a minefield 👊

[@iainwadey2527]

Love the video and detail! I am in the process of applying IWI on the front external wall of a Victorian terrace. I striped back to the brick work, some which showed clear signs of spalling; not surprising given the air gap caused by Dip and Dab gypsum plasterboarding over the original Lime plaster (creating a cavity where moisture could not escape). I have applied around 30mm of Diaphonite Thermactive, then fixed 60mm Uditherm Woodfibre board on that with insulated screw fixings and using the a wet layer of Diaphonite as lime adhesive. Not sure about the results yet but interested in next winter to perform analysis to the temperature, humidity and thermal imaging (not to mention out gas bill!). Just another thing, it was pointed out to me by a builder who works at CAT that there are common misconceptions about interstitial condensation (dew point moisture) and general moisture caused by cooking, cleaning etc. As I understand it, the latter has very little to do with mould growth within the wall structure. Interstitial condensation just requires some cavity where moisture will condense from any air which pretty much always has a certain amount of moisture in it. With that in mind, a safer approach is to simply allow the moisture to escape. Lime is also alkaline and anti microbial. If anyone is interested in Diaphonite or other insulating Lime plasters, I would recommend contacting Carrington Lime in Gloucestershire who run practical and online courses/seminars on the specific products.

[@valborchardt3596]

Thanks for the update Charlie, hope your kitchen walls will be sorted soon….take care

[@markmcgrath4853]

very good video charlie ! i have started thermal boarding my own bedroom which also is a solid wall construction !

[@richardhouston7277]

Hi Charlie now a regular to your channel. Content and delivery is fantastic. Very knowledgeable and informative. All the best

[@CharlieDIYte]

Thanks Richard. Really appreciate you watching my stuff 👊

[@braddempsy9845]

I will be doing this very shortly in my two front rooms. I have decided use PIR straight onto the brick wall, batten a frame in front of it and screw battens to ceiling and floor joists. This way there is no compromise in the insulation. Socks can go in the void behind the stud wall.

[@oldboyuk]

Good stuff. Having looked into internal insulation it's clear that it's a murky area with unclear best practices. Props for trying to tackle the issue and bring clarity on different options

[@albarlow]

Agreed - I've been upgrading my home, which has a cavity wall that the previous owners insulated at some point. Trying to get any consistent information on how to boost the insulation is nigh impossible. I went with a dot-dab insulation approach like I saw on this channel before and it has been extremely effective for me in one room, now considering whether to do likewise in other rooms, it looks like there might be ways to up the game.

[@fgcvhhbvjhbj]

@Alex Barlow dot and dab is fine for most walls as long as there is no shelving or units built there like a kitchen etc. It becomes a pain in the backside though if you decide to start putting up shelves or units after. If its like 50mm insulation or higher. We went with battoning the walls like Charlie here and used two 2x2 stacked on top of each other which allowed us to fit 80mm insulation in between it with a few mm gap for air. We're very happy with it and it's very warm now, even during the last winter. But we also upgraded all the windows to triple glazed from Poland as well. Definitely recommend but either way, insulating is such a great investment. We insulated the whole lot for about £6000 and got the windows for £3500. All the work done ourselves.

[@Eggnog3000]

What brand are the windows?​@@fgcvhhbvjhbj

[@andrewarthurmatthews6685]

Another excellent, simply explained, and highly informative video

[@CharlieDIYte]

Thanks Andrew. I'm still researching this insulation issue as I find it fascinating just how complicated it is/ difficult it is to get right. I feel I slightly skirted over the breathable options so I'll try and do another video with my findings.

[@GaryThomsonJoinery]

Excellent Information Charlie, It’s a cost that you have to be prepared to lose some floor space to gain comfort as well as peace that your property is not rotting away behind the seems. I’ve no problem with loosing some floor space to do this but like everything else in life,,,,, Quality comes at a cost. Thank you so much for sharing, it a great reference video that I’m going to share with a lot of folks. 👍

[@smallfeet4581]

Does the foil go to the outside or inside with gyproc , if inside wouldn't that cause damp on the outside to seep through the gyproc ? , I have lathing plaster and would like to strip plaster out and replace with foil backed gyproc on to battens with foil to face outside in kitchen with foil insulating sheets on to the gyproc then kitchen cupboards on to that , without the moisture issue it would be easy lol

[@philipowen-dixon8492]

Great video Charlie. I've just done similar but pretty much made all the mistake that can be made. Dot and dab'd PIR board to solid stone walls then thought about fitting pattresses afterwards. Lessons learnt and this is the first room so won't be making those mistakes again.

[@CharlieDIYte]

Philip I was the same with the K118 upstairs. Keep an eye on my channel was I'm attending a 2.30 hr training course today with one of the leading breathable insulation providers. I'm be doing an update video on it soon 🔜 👊

[@RS-Amsterdam]

Well thought out. Besides basic logic and research specific materials a great plan. Allow me to share a moisture battle of my own. (not applicable for a problem like yours) As you know I own a lot of garages and one of them had a half brick wall and with heavy rainfall for a long time at a time moisture came through the wall. What I did was, I gave the outside a special invisible impregnated coating, throwing water at it will make it drop on the ground or stick at the wall as drops. Inside I used two component basement coating, once mixed you need to apply it within 40 minutes and it looked like there was a plastic on the wall. Since it still was a cold wall I made a wooden framework and in between I glued polystyrene foam boards against the wall, a tiny thinner than the wooden framework so there is some air between the polystyrene and the wooden panels. Made two holes in the wall, front and back of the garage, with air vents, problem solved. That two component basement coating is so good, it really seals off any moisture coming through the wall. There is no heating in the garage so this was the best solution and no mould. Success with the walls, keep us informed !

[@petervine3488]

When I’ve insulated solid brick walls, I’ve used 50 mm celotex/kingsman straight against the wall, fit the insulation to the walls through 38mm battens, set out to suit the plasterboard, and the 12mm plasterboard to the battens. You can now run cables in the void, cut out drying holes to plasterboard, without damaging the insulation, which is all kept intact & sealed.

[@kevocos]

Interesting video Charlie. Not to be only pointing out issues but I see two potential problems with this arrangement. Firstly there are many unventilated cavity spaces right where the dewpoint position is (internal face of the brickwork wall), surely that is perfect conditions for mould. Secondly, with the batten fixed directly to the brickwall they will act as cold bridges, a studded frame build independently say 20mm off the brickwork would have avoid the cold bridge, or even a "warm" batten with 25mm insulation fixed behind the batten. Regardless an interesting subject where it is near impossible to satisfy all requiments!

[@alanpowell24]

Ideally, that void should be vented in someway to outside air

[@tensense5872]

Weep vents maybe

[@lksf9820]

@@alanpowell24 So when it's -5 outside you've got air of that temp circulating inside of your house walls. This is not a good idea.

[@SenselessUsername]

@@lksf9820 The mould won't grow at -5, effective... :)

[@peterobrien269]

Positive ventilation unit pushing air into the cavity space if its a continuous maze gap with trickle vent exits? would that cause any issues with the inner shell?

[@TheNorthernmunky]

Brilliant work Charlie

[@avisitorhere]

I would use Steico's system of applying wood fiber board to a masonry surface and then finish with either a vapor permeable wallboard or a lime plaster which is also vapor permeable. I would then finish with a vapor permeable paint. You are relying on a cold air cavity to control moisture which will over time probably fail. You are also not allowing the walls to dry out causing them to deteriorate over time. The walls were made to breathe, you have to let them.

[@peterobrien269]

Charlie says its a '2 brick course with no cavity' - we dont know if its a lime mortar pointing(but he seems to allude to that with the proposed lime insulation solution eval). If he currently has a "mix and match" lime and cement mortar pointing(which is typically of older houses with a mix of more recent renovations). IMO Even with a lime internal plaster composite integrated insulation layer(no gap) it may not resolve the damp penetration patches and cold spots due to any prior use of cement.. Charlie's solution, basically a fancy raised dry wall inner shell concept, typically has a ~30 year life before batons and plaster/insulation degrade and damp/mould penetrates, certainly should provide a better U-Rating, terminal conductivity is limited to the wooden batons and that seems to be his No1 concern. Future concern is the stone and mortar health behind the shell (degraded lime due to lack of breathability) and mould builds up on the inner wall surface. Unless you incorporate some air pocket ventilation between the gap of outer shell and inner solid wall to wick away the moisture and control/reduce mould growth, such a wall gap ventilation system would also also help preserve the wood batons extending the life of his solution, help preserve any stone & lime mortar with his walls. Technically it would be interesting to know the temp difference between that inner shell (outer surface) and the inner wall surface and also the humidity of the air gap over time to identify and help ID level of mould and moisture damage.

[@marcinamnesiac3155]

I have implemented external insulation along with mechanical ventilation with heat recovery (MVHR) in my home. While it may not strictly adhere to vacuum requirements for MVHR, this combination has proven highly effective. The system functions like a charm, preventing condensation within the house and maintaining significantly lower humidity levels. This integration has successfully created a more comfortable indoor environment, showcasing the practical benefits of combining insulation and mechanical ventilation for improved humidity control.

[@unknownmale]

Interested in the route you go down, I'm about to undertake this, by using 3x2 CLS stud work to the wall, filled with wood fibre, vapour barrier taped over followed by butyl tape along the studs and noggins so when the plasterboard is attached the barrier isn't compromised. My reason for this route is so that I have good fixings for shelves, radiators etc. It also allows me to get the wall level and plumb which is currently is not

[@avfczoff]

Really helpful video. Thanks so much for sharing 👍🏻

[@CharlieDIYte]

You're welcome, thanks for the comment. 👊

[@DavidJohnson-yg8qm]

Oh dear, this is how the plasterers did my last house in 2001 and I have just checked my current house and it is exactly the same. Well at least I know what the next job is to do. Thank you for your indepth analysis

[@CharlieDIYte]

You can ameliorate any problems David with a good vapor management strategy kzbin.info/www/bejne/hJPXmp1-gN5ljNEsi=PvttgPAugjQfCs01 👊

[@bikerchrisukk]

Very nice job and thought process. 👍

[@CharlieDIYte]

Thanks 👍

[@alexclifford8961]

Woodfibre insulation fully bonded to the wall with lime plaster over or Diathonite insulated plaster would have been the best option. Standard best practice is to not leave a cavity next to the wall as you will get mould growth just like you did before. It is almost impossible to prevent air ingress into that cavity. You also need to remember to insulate between the joists in the inter floor void next to the wall having parge coated first around the joists to prevent air ingress.

[@CharlieDIYte]

Thanks Alex, appreciate you sharing that. 👊

[@FerryFalco]

Hmm, yet perhaps to reduce service penetrations you could perform your insulation then have a horizontally battened service cavity with airtightness layer behind traditional plasterboard. This means religiously taping that barrier behind each socket box and penetration before mounting the plasterboard.

[@FerryFalco]

Better still simply tape the airtight barrier to the Lime insulation, then attach the electrics taking care to seal around the screws. The same dedication would have to be taken for the screws mounting the plasterboard battens. Then attach the boards..

[@looopy2u]

if you screw your 38mm batons horizontally making a grid pattern you will limit the cold bridge. you could also insulate between the batons. Don't forget you need a ventilation system (ideally a heat recovery system) to deal with all the vapor that can now not pass through the walls. A healthy house requires heat and ventilation working in conjunction. The tighter you make a house the more important this becomes.

[@therabman_5606]

Agreed! Nothing will cause more issues that a house that can’t “breathe” it will cause voids to sweat etc and thats almost as bad as having a leak you don’t know about

[@JeffreyBoombastic]

⁠@@therabman_5606would open trickle vents on all windows be sufficient? I’m just about to start insulating our bedrooms and don’t want to create another issue

[@peterreime3146]

the only downside with having the battens horizontal is that you will need to cut through them to run the services from above or below.

[@looopy2u]

@@peterreime3146 you put plastic on the vertical battens and then the horizon battens, you can run the electrics in between the plastic and the horizontal battens, there is enough give. You have to use soft insulation for this kind of solution or if hard insulation must be used then it must be thinner than the vertical battens. The upside to this is that you don't have any penetrations in the plastic. But there may be places where it is appropriate to cut or drill the top batten. One can also put an extra 22mm vertical batten to create space for electrics. There are many solutions to stop cold bridges and have an airtight seal.

[@peterobrien269]

Which is better during winter cold in a more air tight reno: ventilation (ie trickle vents) or smart dehumidifier or mix of both? retain the heat, lose the water.

[@RyanJohnsonD]

This is a very well done video.

[@JulietteBauccio]

Thank you for this content and being so encouraging to have ongoing communication. I'm hoping to add some insulation to my internal walls but am wary of moisture problems. It's incredible how little good information there is out there when it's really such an important topic, especially given the cost of heating a home currently!

[@Fester_]

Thanks for the info. Useful.

[@POUSEaroundtheHOUSE]

Nice video, refreshing to see some common sense regarding the lime plaster. It's a nice idea but like you, the end of my house is solid brick wall and without my wood burner I'd be screwed as it gets really cold and if you can make it warmer then go for it. Interestingly I got damp problems in this part of my house after painting the outside of the house using sandtex paint. I think it stopped moisture escaping outwards, maybe a video opportunity for the future! But I think your option looks good. Unfortunately as you say, many manufacturers fail to include how to deal with sockets, ducts etc and it ultimately comes down to you to come with the best solution. Best of luck with it 👍

[@CharlieDIYte]

Thanks buddy. Sorry to hear about those problems. I've found the Emperor fantastic kzbin.info/www/bejne/sKjCaYyMe7CMZ68 Problem with most exterior paints is they're only water RESISTANT and aren't breathable unlike this stuff. They also do a translucent cream for applying to brickwork you don't want to paint. 👊

[@niallbrennan7946]

For sockets there is an airtightness product that is a rubber gasket with a small hole in it to poke the cable through. I am goint to stick insulated boards directly to wall with adhesive foam with a continuous bead all the away around the edge. The rubber gasket will be stuck to back of the board where the cables will poke through. Then I may use shallow surface mounted boxes or use shallow depth boxes. If the latter I will remove plaster board and some insulation. Then line the cavity with foil tape to renew the vapour barrier. Where the boards but against each other I will use a bead of sealant, something like pro clima, to make the vapour barrier continouus at these junctions. Then foil taping over the the joints before jointing compound or plaster. At ceiling and floor I will use the foam adhesive to make up any large gaps then paintable sealant on top and possible foil tape to floor at ground which will be hidden by skirting and floor covering. Also using same sealant where the boards butt up against window frame. This the best I can come up with as a timber frame would loose me too much room space. Solid brick wall, built around 1911, recently rendered outside with sand and cement and inside with gypsum plaster. To use any of the breathable internal solutions most advise removing all cement or gypsum from the wall inside and out and I just can't bring myself to do it and EWI is eye wateringly expensive. 🤞all constructive thoughts welcome

[@JW-lr1mc]

Well done mate

[@stevenc123]

I live in a 200+ year old stone wall property was completely gutted and renovated in the late 60s. The walls were covered in some sort of bitumen, then a stud wall that doesn't touch the stone was put up, and covered with 3cm thick foil backed plasterboard. I was able to learn all this using an inspection camera when fitting shelves. It seems to work fairly well, although the walls are about 50-60cm thick from outside to inside.

[@mushroom4051]

Tanking,do the same in basements

[@abescheele]

Great video Charlie. There’s an interesting EU project called Ri Build. It’s essentially research being done into the best approaches for internally insulating historical buildings. They have a calc that helps determine the recommended maximum amount of insulation for a given type as too much can introduce potential issues with timber rotting and cracks forming due to frost.

[@CharlieDIYte]

Thanks buddy - that's really interesting. I'm actually going to go with a breathable system now from SWIP. There'll be a video on this later in the year. 👊

[@samm6806]

​@@CharlieDIYteHi Charlie. Any progress with SWIP and your video? How was your experience? I'm looking at their products currently but need to find a local, accredited installer first.

[@togarchitecture]

There are a number of internal wall insulation options that are breathable which is the best option as you get you u-value. These include but not limited to wood fiber insulation and lime render with cork or pumus stone in it put on at about 50m thick. (A friend did the latter on his listed cottage and it's amazingly warm)

[@inh415]

What about air tightness / air changes per hour?

[@DevAnubis]

​@@inh415 breathability and air-tightness are two different things. Materials like wood fibre can help to prevent moisture buildup in walls by absorbing any condensation at the cold surface (assuming good contact with a breathable adhesive like a lime mix). The moisture can then be wicked back through the insulation, and when the internal humidity drops breath out into the room again. Air tightness on the other hand prevents penetration of air from outside. Wood fibre insulation, whilst not completely air tight, does obstruct airflow, and you can get vapour-open air-tight materials, both as membranes and as paint-on treatments. And intelligent valour membranes can be used to prevent/reduce vapour penetration into the wall from the room, whilst still allowing vapour to breath out into the room (usually at a certain relative humidity and temperature range).

[@milanstepanek4185]

@@DevAnubis Yep, i'm looking at this option as well, wood fibre boards from STEICO. It fits in with the "design philosphy" (if you can call it that) of an old solid brick walled house. Back in the day they didnt have the means to stop moisture at any point (sandstone block foundation) and just let it come and go. And they ran direct wood-fired stoves which kill moisture so fast you wish you had more lol. Covering up these walls from any side with anything that stops water is asking for trouble. The wood fibre board solution sounds almost too good to be true as the installation looks fairly simple and doesnt require several layers of whatnot.

[@Zxcbr267]

Brilliant video👍

[@Marcelo.Guerrero]

Subscribed! Thank you for your info!

[@philipdeacon5186]

The lime plasterers will hate you , but as somebody who wants a warm family house think you doing a sensible and well researched refurb .

[@CharlieDIYte]

Thanks Philip. Yes they will! Oh well, warm house here we come. 😉

[@k.hussain360]

Interesting approach, look forward to seeing how it works out. Fingers crossed it works like you want it to. I came across a relatively new product that's an insulated wet plaster/render which can be used internally called proof therm by a company called proof shield. It's a traditional wet plaster with insulating materials mixed in. Showing some quite interesting u-values.

[@roscopeco2000]

thats interesting cant imagine the u value would be great, is at just a skim?

[@narcissusecho7469]

@@roscopeco2000 I just calculated, 220m brick would require an internal plaster layer at 160mm thick for that product to fall within building regs for existing fabric of U value 0.3 - not feasible really

[@roscopeco2000]

@@narcissusecho7469 I have a 50mm cavity with polystyrene balls but it's still cold

[@craigduckworth3896]

Interesting video as I’m currently looking into this for my own house. I have used a product called superquilt in the past on other building projects, and it’s very effective. Not only does it provide a lay of insulation it is also a vapour barrier. You just have to make sure you tape the perimeter and overlap with silver tape. You simply batten your walls and counter batten over the top. Seems to be the best product to stop any cold bridging. I thought I’d share this with you

[@CharlieDIYte]

Thanks Craig, that's interesting. I have a wall on the south side that can't be insulated with anything too thick due to a doorway that's already tight so I'll put that into the mix 👊

[@tomfallon4991]

VERY GOOD CHARLIE YOU IDENTIFY ISSUES & THEN RESOLVE THEM YOUR BEST BET IS YOURSELF I THINK YOU ARE A PROBLEM SOLVER, DISREGARD ALL ARMCHAIR GENERALS. REGARDS TOM😊

[@Rob-ln7dd]

Great video Charlie. I'd definitely install an MVHR system if you can. I renovated a 1790 farmhouse in the French Alps, wanted to expose the stones but Mairie insisted on render so I insulated outside with Kingspan K5, (fireproof) and rendered over that, then lime plastered inside, external walls, plus lime wash paint. Dug down, underpinned and insulated the foundations, dug down rafted concrete floors on 300mm foamglas gravel then underfloor heated everything. The house is at 1100m, it's about 250m2 and costs about £1500 year to heat and DHW.. where the temp is -5 to -15 for appx 3.5 months whilst house is 22°. I'm a sparky but did the design, planning and work myself. Took a while mind you ! Love the channel....

[@CharlieDIYte]

Thanks for that mate. Wow, what a project!! Sounds similar to what I'm having to do right now with foundations missing on a corner of the kitchen. I've decided to go with breathable insulation inside now, given the exterior render isn't breathable. Also lowering the outside ground which will help damp issues on the walls.

[@Rob-ln7dd]

@@CharlieDIYte sounds good, lower the ground and try and incorporate as much land drainage as possible. I like those humidity monitors your have, An MVHR will give you a finely controllable tool to manage humidity and hopefully stop any potential condensation before it starts.

[@stevenm8970]

@@CharlieDIYte Hi Charlie. I have the exact same problem as you, tyrolene render on the outside, solid walls. What types on breathable materials did you insulate with? In what order and method did you install them? Thanks

[@demios300]

Fix the studs top and bottom so you have no bridging back to the wall. 10mm gap for insulation is good, allows the foil to reflect infrared back. Try and stay away from PIR these days because of the poor fire performance but appreciate it's better thermally. Take a look into rockwool and a separate VCL like visqueen which you can staple to the face of the studs and cut down the joints. You also wouldn't need the gap for cables with this as its more flexible which might help offset the performance difference. FYI you can get thermally broken insulation fixings to reduce the bridging.

[@michaelplays2449]

Great video !! thanks

[@practicepatch3506]

I've just insulated a north-facing kitchen wall using 4mm cork roll, bonded, full contact, with tile cement (diluted 1+5/PVA+tile cement), to the existing plaster/wall. (The wall is a cavity wall). Hopefully this will mean there's no void to collect moisture. The result so far is signicantly reduced condensation, with a marked increase in temperature of the room. The cork was treated both sides with a diluted PVA 'wash' prior to application, to help with cement bonding. Is working for me!

[@davidhale8034]

Great video

[@patrickflanagan8008]

Love this channel.

[@CharlieDIYte]

Thanks Patrick 👊

[@edhunter84]

When doing my bedroom i battened the walls and as the walls were so uneven i used plastic shims to bring them off the wall then used a closed cell expanding foam sprayed behind the battens to stop them flexing, reduce sound and act as the damp proof membrane. I trimmed back any spill out the side of the battens with an old saw then filled between with mineral wool insulation. Then went over all this with my vapour barrier and plasterboard.

[@CharlieDIYte]

That's an absolutely top job. Great work. Yes I've considered rock wool. It means having to install an additional vapour barrier as you say but it's not totally off the table right now. 👊

[@user-cn1em2qx6f]

what size battens did you use? did you go for 100mm. or a smaller size and compress the mineral wool in

[@Oppledom]

Hey Charlie, I haven't watched it all but there are a lot of options to insulate with lime whilst still maintaining a vapour open construction. There are cork insulated plasters which can give a good u value, also wood fibre with lime plaster would be vapour open too.

[@alexanderockenden2564]

This is a far better option IMO. Insulating breathable lime render directly onto the masonry. Vapor barriers and whatnot to keep internal moisture out of the space between the plasterboard and the masonry are never going to be truly airtight and therefore moisture in the air WILL find its way behind at some point.

[@andrewandlm]

Well. That was, without doubt, the best vid on insulation I've seen... 👌

[@CharlieDIYte]

Thanks, really appreciate that 👊

[@james83777]

In our solid walled home I sealed round the edges of whole sheets of foil backed PIR (celotex etc) with silicone and put that directly onto the plastered wall. Then fix 50x25 tile battens over this to mechanically fix the boards to the wall foil tape the joints then fix the plasterboard to the battens. Gives a nice 25mm warm void behind the plasterboard for the sockets etc with no interruption to the vapour barrier. The whole wall is completely covered with insulation no battens in the way. Also no chance of the battens rotting as all on the warm side of the insulation. Would say the walls are almost air tight in theory.

[@asilver2889]

Life of silicone?

[@james83777]

@@asilver2889 more of a belt and braces thing to help with airtightness between the board and the wall. The boards are squashed so tightly to the wall by the mechanically fixed battens I very much doubt any moisture that might find it’s way past a failed bit of silicone in 20 odd years will cause much of a problem.

[@fgcvhhbvjhbj]

I battoned and insulated the entirety of a derelict cottage that we bought a year ago. It's very warm now and we're very happy with it. We went with 80mm xtratherm and used 4x2 for the batons. There was a few mm gap behind the insulation then as well so we didn't bother putting more batons on top because we were tight for room space. Very happy with how it turned out.

[@fgcvhhbvjhbj]

I also bought the Gapotape but found it a bit of a nuisance so ended up not using it mostly and just made a jig to cut them all the correct size to fit tight in the batons. Foamed in any gaps with Hermatic expanding foam

[@afnankhokhar5578]

Fascinating topic. I'm not sure if I'd be willing to lose c.140mm of space internally - that's a lot of volume when you think about how big your external wall is. That said, your idea does seem very comprehensive at addressing the issue of heat loss

[@CharlieDIYte]

It's really only on the one wall in the kitchen so once it was up we won't notice. More of an issue is in the other part of the room where we have a doorway that is already narrow. ..

[@asilver2889]

This is where insulating plaster (Diathonite, Bauwer etc) can be a 'safer' option. Slightly less insulating, but thinner and no air gap.

[@DaddyBear3000]

Solid strategy. Only think I might consider is if you’re looking to put cabinets on the wall I would think about using double thick plasterboard and substituting the inner layer with ply behind wall cabinets for strength.

[@CharlieDIYte]

Thanks. Yes I'm thinking of doing this. I'm also just researching all options including breathable to make sure I'm not missing a trick. Will do a video update at some point.

[@DaddyBear3000]

@@CharlieDIYte good point. The issue is trapped moisture rather than moisture per say. I’ll look out for your update 👍🏼

[@wiseman8958]

Just amazing!! 😃👍🥇🏅🎖

[@jayt9181]

I have solid walls. I'll be fitting internal wood fibre insulation to my outside facing walls. Then applying a lime plaster. Hopefully that will keep the room warm, breathable and dry. My house is having a few mould issues due to external cement render and internal gypsum plaster. I'll be removing the render over easter and chipping away room by room with IWI and lime plaster.

[@JulietteBauccio]

Hi Jay, interested in this because I'd like to do similar. Have you chosen specific products yet? It's seems very hard to find options that aren't gypsum!

[@asilver2889]

Check out "the warm dry home" Pete Ward for advice if you want to stick to first principles and traditional materials.

[@darrensmith7853]

Your house will thank you for it and so will your bank account

[@jayt9181]

@Juliette Bauccio I have yes. I will be going for the steico wood fibre insulation, 30mm for my first project then hopefully go thicker in places where I can.

[@jayt9181]

@a silver oh yes, I found his videos soon after I moved into my victorian home. I honestly didn't realise how much cement and gypsum damages soft red bricks. I will be repointing all the bricks in new lime morta. I am actually going to make my own lime putty soon as its quite expensive.

[@paulhaggett3710]

Love listening to your logic Charlie. Im sure your method of dry walling will work, youve probably completed by now. Didnt know you could get an IR camera for your phone. Best method ive used is to sheet wall with polythene, attach tannalised roofing lathes, infill with polystyrene, plasterboard and skim. It is simple, doesnt take up much internal space and inexpenive. I agree with everything youve said but feel you may be over engineering things in light of all the problems youve had with mould. Good luck with everything- great to discuss.

[@CharlieDIYte]

Thanks Paul, really appreciate that. I'm actually going to go with a breathable insulation system. Will be doing a video on it soon. Watch this space 👌

[@johnturrell942]

Very interesting. Im guessing only a small percentage will tackle such upgrades. I pondered this method for the front bedroom. However I am not a fan of wood in any environment that may have moisture. Also limited to 60mm space loss. I stuck with Thermal plasterboard with dab. no cut outs and pir joints with PU adhesive. Coupled with insulated ceiling all toasty and warm.

[@CharlieDIYte]

You've done absolutely the right thing there John. PU adhesive every time - puts no moisture into the wall unlike adhesive and much better at tackling cold bridging between sheets. 👌👊

[@johnchapman5646]

The audio in your videos is a wiiild ride, Charlie! Nevertheless, thanks for the great content!

[@CharlieDIYte]

Sorry about that, John. Perhaps wasn't wearing the lapel 🎤.

[@johnchapman5646]

I meant the little 'correction' insert voice overs you do - always gives me a laugh though, don't change!

[@darrenpaulgreen]

Really interesting series Charlie. We live in a Grade II listed building, so although I agree with your arguments for going with internal insulation, it isn’t unfortunately an option for us as we’d never get listed buildings approval for the works (and would end up with an unsaleable property if we went ahead without approval). Over the years, gypsum plaster has been used to reskim some walls and damp/mould is a constant issue in these areas (presumably because it’s less permeable than lime plaster). Even with a decent central heating system, log burner and moisture control, getting RH to under 60% is almost impossible. Upshot is that we will be moving and wouldn’t buy a listed building again, sadly there are just too many restrictions which prevent them being suitable for modern living 😢

[@CharlieDIYte]

Thanks Darren. It's sad isn't it how the restrictions on heritage stock make it so difficult to live in. I'm actually researching breathable insulation right now so keep an eye out for the next video. May not go down the PIR route. 😉

[@prestonian1066]

Yeah it's criminal that so many listed buildings will eventually be destroyed by the very people supposed to be protecting them, because of imposing some crazy rules. The sad truth, is that it would be wise to stay clear of these buildings.

[@Happytruth]

If you get any kind of penetrating damp from the outside you can still get mould issues, I worked for a guy who wanted his whole house done with insulated plasterboard dabbed onto the walls it was in an area with a natural spring and sometimes a high water level so I advised him against it but he insisted the walls were dry so I did what he asked only to find that he got mould spores behind the plasterboards. What people and companies forget is you only need a small bit of mould that will spread and spread even with intermittent damp.

[@dudeleboski2692]

Great info

[@CharlieDIYte]

Thanks.

[@gdfggggg]

I would have dabbed 50mm PIR to the walls and foil taped the joints, then mechanically fix the boards to the wall with plastic 10mm board fixers. That way you’ll get the walls nice and straight. Next, I’d have fixed the plasterboard to the surface of the PIR with expanding foam adhesive. Soudal do a great glue and very easy to use. I never buy insulated plasterboard as it’s twice the price. Battening a wall creates a cold bridge.

[@nickjohn9085]

That was an interesting video. Only thing i would add to that spec' is a sheet of 11mm OSB behind the plaster board. Not that it will have any meaningful affect on either vapour or heat control, but it makes fixing things (shelves for example) easier. Nothing worse than trying to fix a 500mm wide wall cupboard that isn't widen enough to span between the studs or is wanted in a position that won't coordinate with the studs. Apart from that, i am with your design rationale all the way!

[@CharlieDIYte]

Thanks Nick. That's a decent shout. I was going to install patresses wherever I'm fixing units etc but OSB sheets would future proof things.

[@ianscottuk]

I don't know if I was overkill or not, but I built a stud wall 50mm from a granite wall with 100mm deep timber. I then put Kingspan pir 100mm with gapo tape. Where the sockets are I put two noggins directly above and below the box, and a bit of ply out the back and expanding foam to fill. Then I put a green vapour barrier up, and plaster board ontop, and got a plasterer in. I then used a vinyl mat paint as I hope it will block vapour also, but for me the 50mm out the back provides a ton of ventilation from the attic. Let me know if anyone can see anything wrong with the setup as I have all the other bedrooms to do this summer!

[@uksnusreviews9455]

Really looking forward to seeing the end result on this kitchen, Charlie

[@exubre]

This is such a good video! The approach makes complete sense however I wondered if sealing the wall could trap rising damp? Or is rising damp not an issue at this property? I'm not trying to be clever here, I just have a similar challenge ahead and am formulating the plan!

[@m0aze611]

brilliant - thanks

[@CharlieDIYte]

You're welcome 👊

[@kirkby0076]

I believe, that putting some far infrared panels in for heating or supplemented heating, would be a very hood idea here 👍👍

[@David-mb3eq]

Not sure about others but kitchens I recommend moisture resistant plasterboard on walls due to humidity and ceilings fireline plasterboards even on single storey extensions for the sake of the small extra cost its extra protection incase of a fire usually you have off cuts from covering the RSJ

[@CharlieDIYte]

Thanks David. I hadn't started thinking about the fire considerations yet but that's a good point, as is the moisture resistant board point. 👊

[@Tephnos]

From what I've understood, the best option is to go for least breathable to most breathable (inside to outside), if space allows (which is the main problem in the UK and why we love PIR). So that would typically be a layer of PIR just under the plasterboard which also acts as the VCL if done right. Beyond that, lots of breathable stuff like rockwool. This assures that any moisture that does pass through (which there will always be, screw penetrations, gaps in tape, etc. always assume there are gaps unless airtightness tested) has a sufficient 'gradient' to evaporate and not condense by immediately hitting a brick wall of impermeable material. I also noticed that in your bedrooms you did a 25mm layer then a 50mm layer over the top. Apparently this is non-advised due to the gradient stuff I mentioned before. You typically want the thinnest layer at the top, and the thickest layers where it is colder, this helps avoid any interstitial condensation. Last thing I'd say is those metal bracket things you mentioned for the socket boxes? They're duff, IMO. All they do is create nice little bumps on your flat plasterboard when it goes over the metal hooks. Stick to 4x1s for secure anchoring of backboxes.

[@slashingbison2503]

My Victorian house humidity is often 60-70% when it rains , or 40-55 on a good dry day I have found if its kept below 70 there are no issues When we had 75-80% before I got the dehumidifier there was grey mold on books I also have a downstairs bathroom with no fan (and shower) and no kitchen hood so it was all condensation.

[@randomfocus1549]

Not sure if you have it in UK but in NZ theres this product called Crystal, its a non decorative coating you paint/roll/spray onto concrete. The crytals in it actively seek out moisture in the concrete and it becomes a complete waterproof sealer. Typically used in existing subfloor basement concrete walls.

[@CharlieDIYte]

Thanks, that's really interesting. If nothing else could be really useful for the bricks below the dpc. A quick Google suggests we don't have it here though ..

[@randomfocus1549]

@@CharlieDIYte bit lazy of me its called Crystal Proof. I believe theres many brands that make a similar thing but here its made by Cemix which is probably an Australian company. I believe most local concrete workers probably know the equivalent in UK?

[@inh415]

Sounds like some of the tanking systems used here.

[@kolbszabolcs1241]

We have something similar in Romania, but we call it glass water. You apply with a brush and roller and make the wall 100% waterproof and block water infiltration from outside to inside

[@alfamad155]

Charlie it’s well worth looking into spray cork. I spray for a company called Corksol

[@philipnorbury354]

Hi Charliediy, really appreciate your video very well done. I see the batons represent a significant cold bridge. Did you consider foam glue ? I used foam glue which unlike dot and dab and batons is foam insulation so no bridge and it worked. Still need vapour barrier but again foam glue on phenolic. My new project we are using breathable Lyme plaster x 3 layers plus final coat of aerogel plaster which for 10mm has same u value as 75mm of PUR board. Phil

[@sapiotone]

Budget constraints have been the driver for our project. Inflation and cost of living has seen our specs drop from EnerPHit to AECB, then down to "do whatever the heck we can afford to make the place warmer". All our external walls have 40mm EPS plasterboard IWI; the north wall will have 50mm EWI as well; and the south/west facing walls will have 20mm silicone render. I'd have liked to have gone with icynene spray insulation in the roof, but being an Edwardian terrace, it would have made remortgage impossible. So we've stuck with 100mm PIR between the rafters and 70mm over the top, cross-battened and plasterboard over. Unfortunately the builders haven't done the best of jobs of fitting the PIR. I bet there's cold spots everywhere, but we've just gotta suck it up with the build quality and follow Charlie's earlier advice on ventilation and damp control

[@trimmxx2169]

Hi Charlie i have been looking for this advice everywhere thankyou! I am doing similar but my walls have rising damp (solid walls) looks like it has been plastered not lime so hopefully once removed it will subside. im considering using dry rods as a chemical dpc before using said method you are doing any advice would be great?

[@elthamlad468]

Came across this video while researching how to repair a damp wall. Like you previous owner of my house has dot and dabbed standard plasterboards to a thick, solid external ground floor brick wall, and needless to say mould has penetrated the plasterboard and is forming on the walls. Over the years the external rendering, which would have originally been lime based, has been replaced with modern render, so the walls cannot breath properly. All in all, an absolute mess. I am at a loss to work out how I can fix this mess without incurring substancial costs. If you speak to 10 different experts you will get 10 different answers.

[@RyanJohnsonD]

Excellent

[@CharlieDIYte]

Thanks 👊

[@SKMusic1985]

This is very useful for when I renovate my Victorian kitchen, cos it’s basically the same, except we’ve got plaster on brick and no board at all (it’s freezing) !!!

[@CharlieDIYte]

I'll be doing an update video soon. I think I'm going to go down a breathable insulation route so keep an eye out for that.

[@awantamta]

Very interesting

[@CharlieDIYte]

Thanks 👊

[@pumpkinhead456]

When doing our bathroom and dressing room, I built the stud 25mm off the wall, fixing to ceiling and floor. The space behind was ventilated both through the wall and to the loft. Then insulated between and over the studs. The void for services will be handy in the kitchen. If I do more internal insulation, I'll go with aerogel and/or wood fibre, both of which are breathable and make a nicer internal environment. I've gone off PIR as it's stinky and not the nicest of material to be wrapped in. Hope that helps!

[@CharlieDIYte]

Thanks 👊

[@makingitthrough190]

Any thoughts on Insulating Lime Putty? Or a hemp/lime render?

[@rhiggins861]

Should be like plastered direct to the wall, maintaining the thermal mass of the building. Use insulated lime -hemp plaster - hot lime/perlite/hemp.

[@SkillBuilder]

As Charlie said, he won't get enough insulation with that method. There is a good reason that you can't buy insulated lime -hemp plaster from builders merchants. It is a niche product and won't meet building regs.

[@simplysimon9868]

Insulated plasterboard, 40mm, battened with a 20mm gap between wall and battens shouldn't get damp or mouldy. No mechanical bridge then. Also outside use perp weep vents. There is a gap between bricks so some air flow can dry out condensation. I've used these on lime mortar brickwork renovation above a slate damp course. Buff colour blends in well with lime pointing. One particular house had damp external walls and took around 6 months to dry fully with soft red bricks but all good and customers happy 😁🙏 Check gutters regularly so no leaks or blockages. Soft bricks can soak up a pint of water each quite easily, Charlie.

[@CharlieDIYte]

Thanks. I used 40 or possibly 45mm K118 upstairs here. It's very effective albeit not building regs compliant from a u value point of view. I like the idea of the weep vents. 👌👊

[@simplysimon9868]

@@CharlieDIYte no ye olde building regs in an old house 😄 Someone in the 80s had drilled small round vents in and looked terrible with cement so changed the bricks and put weep vents in every meter or so.

[@henrywaterhouse6291]

Use kingspan , use instastik foam to stick the boards to the walls . More efficient than battons, and no thermal bridging. Foam to fill gaps board to board and corners. The maximum load I have on a 8x4 is 200kg. I have been doing this for over 15 years and never had any issues. It's alot simpler one step application that maintains the vapour barrier and insulation. Preparation is key to get good adhesion and finish.

[@CharlieDIYte]

Thanks Henry. I'm kicking myself for not mentioning Instastick because as you say it's far superior to plasterboard adhesive. That said Kingspan still recommend mechanical fixing - do you do this? I know a lot of people don't but it's for fire regs compliance.

[@henrywaterhouse6291]

@@CharlieDIYte fire regs is a funny thing, if you used plasterboard adhesive on boards it would be fine, instastik has a B2 fire rating, so does have some rating, plus in theory you are putting a plasterboard covering on, if you put a 15mm mega deco board on your encapsulating the kingspan, you have impact resistance, fantastic fire resistance and the finish is so smooth. I have had the debate with building control about vapour barrier, adhesion etc, basically I took it to the head of building control, gave him the technical and they now support using it. I think the issue is that kingspan recommend mechanical fixing, due to they are looking at their product alone and not in conjunction with another product. At the end of the day in terms of fire risk, you are holding a insulation sheet on to a 9" wall , you don't need fire protection for the structure. I've used it in single skin garage conversions, 100mm kingspan, higher U value that the architect specified, takes me less time to do, I earn more money as I'm on price, very happy customer, they say it's the warmest room in the house. If you wanted to mechanically fix, you could stick your sheets , then put masonry screws with washers before the plasterboard goes on, a happy medium if in doubt. The key to sticking a foil sheet is preparation, weak SBR bond on walls first to cut down on dust and loose material, then make sure everything is sprayed with water. It increases the bond, plus speeds up the cure time. So far I've found instastik the best. Fastest cure time, so I'm not stood around long, it's more expensive than other brands, but it does the job.

[@sidperry7748]

I insulated my garage walls ( 4 inch brick wall ) to turn it into a habitable room I could use , this is the order how I insulated it 1) 25mm pir tight to the wall and foil tape joints 2) 4x2 timber stud wall with 70mm pir in between to allow a gap for wiring to sockets etc 3) vapour barrier stapled to studs 4) 25mm pir over stud wall and tape joints 5) 12.5 mm plaster board The first 25mm layer of pir was to stop any thermal bridging. I had to put a warm flat roof on the garage so that meant there was no air flow to the brick work unless I put an air brick in top and bottom of the brick wall but that meant I would lose more floor space in the garage, so I put liquid dpm on the walls to stop any moisture coming through the brick from the outside. I also applied liquid dpm on the garage floor and dpm plastic membrane on the garage floor and lapped it up the wall by 500mm . Any comments would be welcome if you think I am going to get problems by doing it this way

[@davideyres955]

Looks like you have sealed both sides of the inside and the wall. If you have single skin brickwork then you can get some wicking in of moisture from the outside and that would stop it but the issue you have is your are effectively trapping the moisture inside. It depends on how much moisture you have in the room and how much ventilation you have. If you had a bathroom/kitchen etc in there then you’ll need some form of extraction and a way to bring in less humid air. It’s done now so I wouldn’t worry about it. Just buy a humidity meter and keep an eye on the levels and if they get excessive then consider a de humidifier or another solution.

[@sidperry7748]

@@davideyres955 thanks for your reply , and I agree with you, just keeping my fingers crossed

[@Pete.Ty1]

👍👍👍Thank you

[@avisitorhere]

From Roger Barnes youtube video, "Escape to a French Fishing Port". Roger is an architect and working on an old stone house. To add insulation, he is adding 3cm of clay and hemp to the interior stone walls (sprayed on) and then covering with a lime plaster. You can check out his video, he explains it all (with diagrams) much better than i could.

[@ghollidge]

Id gyp-line the walls with rubber gromits to reduce cold bridging. Use 75mm insulation on to the gyp-line , tape the insulation amd then board over ot. This ensures that there is an air gap for the brick to breath, but would do what you want

[@pauldolton9118]

I would like to see the follow up video of this

[@jonneymendoza]

Quick question. what solutions could i use when i replastyer my hallway? that side of my house is detached so the walls on the hallway are external but the thing is that the insulation plasterboard u used is very thick and i have my staircase in the way and cant really put think insulation plaster

[@lewisnicholls8443]

Been researching this for a few weeks, came across the latest advice on maintaining the original moisture strategy - vapour open in my case, and so have been thinking about wood fibre insulation followed by lime plaster. Any research of yours led you to think about that?

[@CharlieDIYte]

Hmmm. It's a tricky one Lewis and I totally understand where you're coming from. This is a good article on the subject. The one thing that stands out for me (you have to navigate somehow through the speel - which is often designed to advertise as is the case here, a particular product) is the admission that it is still important to restrict vapour transmission into the cold surface (brick). My worry with vapour open is two fold I) the breathability of the wall won't be enough to counter the interstitial condensation and ii) with this race to net zero the govt are forcing us down, a traditional vapour open strategy doesn't give you enough insulation to enable switch over to a heat pump should you be forced into this further down the line. www.acaraconcepts.com/wood-fibre-insulation/insulating-historic-buildings/

[@MrBrunes]

There's a detailed look at mould and IWI issues by Joseph Little, Technological University Dublin - "Breaking the Mould 5 : Comparative simulation of internal insulation systems". He's done a series of articles but #5 this is quite an accessible "starter for 10". Looking forward to Charlie's upcoming views on vapour-permeable methods to see if they are viable in the "real world" as some tend towards rather purist eco/eye-wateringly expensive sol'ns that pose challenges to many.

[@CharlieDIYte]

Thanks, I'll take a look at that. After a breather I'm about to start on the kitchen again - the video on breathable systems is in the pipeline 👊

[@MrBrunes]

​@@CharlieDIYte "After a breather" LOL @ the pun! I sense that "breathable" is going to become a common snake oil term with lots of possible meanings exploited by all sorts. I also found *another* study, this time by Historic England which compared PIR (in two forms) and wood fibre with solid walls. "A Retrofit of a Victorian Terrace House in New Bolsover: A Whole House Thermal Performance Assessment". Apols for the doc overload!

[@Farmer_26]

Man I’m totally lost after watching this video I have a wall that has a small amount of old insulation inside then lathe and the plaster has been removed I had bought the pink foam boards I was planing on glueing directly to the lathe then putting drywall directly on top of the foam board All this talk of mould has freaked me out , should I not put the foam board onto the lathe now? I’m assuming the lath with insulation behind it creates the gap that’s needed behind the foam board but can I attach drywall directly to the foam board at this point ? Or does there have to be a space between the foam board and drywall ? The old system had drywall right on top of the plaster and no vapour barrier and it was all good inside but now I’m wondering if the foam board will cause me a issue inside? If this idea is ok is there any point of adding a vapour barrier between the foam board and drywall? I’m guessing the foam board is my vapour barrier ?

[@octaviaholman5825]

Charlie I’m trying to insulate my walls myself. I was going to batton and then attach k118 to those. The walls/ old plaster board were damp and mouldy - do you think this will not solve the issue?

[@robn749]

Great video Charlie, I have a similar job and this mentioned all of the same concerns that I’ve been wondering about myself (non-continuous vapour barriers, cutting holes out for sockets plumbing etc). I’d be interested in hearing how your installation went and how it’s holding up? Did you use any form of DPM behind the 4x2s or was it not necessary?

[@robn749]

Apologies. I’ve just realised you mentioned the DPM already.

[@CharlieDIYte]

Mate, I haven't done it yet and think I'm going to go with a breathable insulation from a company called SWIP. Watch this space...

[@frankief7111]

Thanks for sharing your process, love your videos. Your focus seems to be on moisture from inside condensing in the cavity. Is there any concern of water from outside coming through? Other than protecting the battens with vertical dpc strips is there nothing else to do there, e.g. no tanking needed? Another thing I worry about are air gaps: I guess air gaps increase insulation effectiveness. But wherever air can flow, moist air can flow, so why not fill air gaps with foam? Just one missed spot tape would let air in no? If the dew point is in the middle of impenetrable foam wouldn't that be better?

[@Swwils]

As far as I can tell vapour doesn't just spontaneously condense in the middle of materials, even if this is where the dew point occurs, it has to condense on the coldest surface of that layer. I think Charlie is using an air gap at the back just encase there is any moisture issues with the solid walls then another on the PB side as a service void so he can have ridiculously deep back boxes.

[@frankief7111]

@@Swwils no air gap = no surface

[@tomthiele6096]

You are correct in the middle... you should use a breathable insulation like wood fibre a carrier board and then lime render.... it doesnt have to be cold and only use lime render. You shouldnt use a vapour barrier on a solid wall because you will have the exact same issue you are trying to fix.

[@CharlieDIYte]

Thanks. Here's what I actually did kzbin.info/www/bejne/haaUdJ2tm9GNqq8si=J4R-YpbYMRW7a9zD

[@steveg59]

Hi, could you let me know which phone thermal camera attachment you use? Cheers. Steve.