Adding extra insulation behind Kitchen Cabinets on external extension wall worth the effort?

Quay_Koncept

I currently have my kitchen cabinets pulled out from the wall, and I'm considering whether it's worth the time and effort to dot and dab 27mm insulated plasterboard with adhesive foam directly onto the existing painted wall. (The extension gets very cold in winter) I saw someone do it in a video (https://www.youtube.com/watch?v=nSnbMsSzdXU),.

Or do the cabinets themselves provide enough insulation as they are effectively air cavities? In that case, I could just apply the plasterboard above the units. (No need to mess with electrical outlets etc) The extension wall is noticeably thinner than the original house, which is why I'm considering this option. I have attached a diagram of the wall construction.

Initially, I thought of using Wallrock Thermal Liner wall covering, but since the kitchen is pulled out, I thought it might be better to do something more substantial. Despite being a very cold room, there are no issues with mold or dampness. Unfortunately, my budget is extremely tight, and I can only afford a DIY solution. Any thoughts or ideas?

looksee

I wouldn't depend on the cabinets to provide insulation. I did a (fairly crude) similarish job in a previous house as so many holes had been knocked through for water outlets etc that there was a howling gale coming in through the cabinets, as well as mice. A bit of patching sorted both, though a lot of the draught was coming through the poor seal between the suspended floor and the wall, which I also fixed while the cabinets were out.

Just do it. If the space behind the cabinets are one of the coldest points in the house they will eventually develop mould/rot problems. These problems will be far worse since you will not be able to see the source and they will have a negative health impact. 27mm is very marginal to see any benefit.

Quay_Koncept

Thanks looksee and Shoog,

Ill definitly apply some insulation so before pushing the units back into place. have some left over fibreglass attic insulation i might stick under the cabinets behind the kick board.

Sleeper12

I wouldn't dot & dab the insulation. This provides a small gap. I would add a vapor barrier & then the insulation tight to the vapor barrier. Insulation should be fixed directly to the wall using the correct fixings designed for the insulation

Quay_Koncept

Thanks Sleeper, Just googled that, yes great advice thanks,👍️ video attached for future viewers of thread as to what the Vapour barrier does https://www.youtube.com/watch?v=fSdD9r5K4RU

I notice there is no vapour barrier in behind the original plasterwork, looks like the builder cut some corners lol

10-10-20

Better idea and cheaper: forget about dot and dab as well as insulated plasterboard and install solid foam boards using expanding board foam.

https://www.goodwins.ie/products/xtratherm-polyiso-rigid-foam-insulation-25mm-2-4m-x-1-2m.html?filter_set%5B%5D=1413,1426

I have done this on a cold extension to limit the condensation on that wall when drying clothes. I noted less cold air filtering out from around the fitted dryer and washing machine and it was an easy fit.

Just get used to applying the foam from the plasterboard cans - it should be applied in a narrow bead to a board in an 'n' shape with the base left open and then partially infill the center. Let the foam 'go off' and then stick the board to the wall with a good 1cm gap at the base to the floor and hold it in place. It does tend to expand outwards so check it every few mins and after its fully solid then fill the 1cm base gap to seal it up.

Quay_Koncept

Interesting,I take it you do this just behind your lower cabinets out of view? Did you skim over this or just paint it, and did you hang your upper kitchen cabinets off this foam board? Im planning to do the full wall above cabinets as well and because its foiled on each side I dont think its possible to skim and paint so might not look great.

Im not sure it works out economically either as these 25mm Foam boards are €26 & you can get 38mm & even 50mm Insulated PB for €37 euro more per 2.4 x 1.2 Sheet. Maybe im missing something though

Calahonda52

https://www.boards.ie/discussion/comment/120854418#Comment_120854418

As noted by Sleeper the key issue here is the bare block which is not airtight.you need to solve this issue first before applying any isolation.

If you dot and dab on the wall as is it will do nothing for air infiltration.

As a matter of interest, are there any wall vents in the extn?

If there are you can tell what the wall make up is.

If it is a cavity wall and the wall vent is not ducted in an airtight way across the cavity then the cavity is in effect fully exposed to the air.

Common problem in 100's of houses/extensions

Try and get a copy of this free document from NSAI

S.R.54_House_Retrofit_Guidelines_2014 updated in 2022

the link on the nasal site os broken

10-10-20

Yes lower cabinets and out of view. You can drill / screw through the insulation and mount pipes etc as you would resting on the foil.

It's just an option, might not suit your needs.

Quay_Koncept

https://www.boards.ie/discussion/comment/120857321#Comment_120857321

Hi Sleeper, There are no air vents at all, the builder never even made one for the extractor fan that was left unplugged (he was meant to🤐). Im going to remove a few square foot of plaster board this afternoon that was water damadged and drill a small pilot hole later today to see if its solid or cavity. Despite having no air vents you can feel draughts from all the electrical outlets and screw holes which I assume is coming from the badly insulated roof above. Im surprised the air can pass right through all the layers of yellow fibreglass so effortlessly from the ceiling. Is there supposed to be some amount of fresh air passing through these fibreglass cavities into the room to allow the wall breath and stop mould damp or is the goal to stop all air passing through into the room from these walls?

Sleeper12

https://www.boards.ie/discussion/comment/120857369#Comment_120857369

@Calahonda52 will hopefully be back to give you advice. I know a little bit about insulation but Calahonda52 deals with this type of thing on a daily basis. If I needed advice on things like this, he would be the one I'd look to. He likes to build up a picture before he gives advice so he asks questions first.

dathi

https://shop.standards.ie/en-ie/standards/s-r-54-2014-a2-2022-877610_saig_nsai_nsai_3214983/

if you click on the preview button on the above site you will see the code of practice that calahonda was talking about

GreeBo

Is it a suspended timber floor or a concrete slab?

27mm is only giving you 15MM of insulation, its hardly worth the effort.

Since you have the extra space due to the thicker original walls I would use a 62mm board (50 + 12) and just screw to the existing studs. You should have a vapour barrier so you "could" staple one to the studs first, however you might have an issue with interstital condensation as the 50mm will be warmer than the existing fibreglass.

Alternatively fix 25mm sheets to the studs and tape the joints. Then use 37mm insulated slabs over the top. This is better than just relying on the foil backed 50mm since by taping the joints (with the foil tape!) you are creating a continuous vapour barrier. note that it should also be taped to the floor, ceiling and the existing wall.

listermint

https://www.boards.ie/discussion/comment/120856773#Comment_120856773

This is great stuff.

But caveat when foam has set mechanical fixings should also be installed especially in fire zones like kitchen or escapes like hallways. There's a risk of delamination of boards blocking exits so mechanical fixings for prevention of this is a must.

I think it's also regulations imho

10-10-20

https://www.boards.ie/discussion/comment/120870514#Comment_120870514

Agreed, it is, but mine are adhered under-counter and not the whole height of the wall, so aren't 'structural', hence no mushroom fittings.

But the points made by many on here since - relating to the makeup of the cavity-block wall and VCL's - are far more impinging so I'd disregard my advise here and recommend something akin to Sleeper12 & GreeBo's suggestions.

Quay_Koncept

https://www.boards.ie/discussion/comment/120870484#Comment_120870484

Hi Greenbo, its a concrete floor with tiles on top. Sorry for a stupid question but do you mean remove the current skimmed plasterboard present wall to reveal the original wooden studs and fibreglass? Or attach the 62mm IPB to the wall but first lay on a vapour barrier?

Interestingly enough over last few days a bit of googling brought me to the SEAI warmer homes grants, I am able to get a grant to do some insulation work on the house (Probably take a year plus to have SEAI assessment) Will have to weigh up if its worth my DIY attempt or leave it for the proffessionals😊 Some great advice on this thread thanks guys :)

GreeBo

https://www.boards.ie/discussion/comment/120871002#Comment_120871002

I'd remove the existing plasterboard first and see whats there.

Depending on the quality of construction you might find the existing fibreglass is useless and you are as well off removing it and replacing it (either with properly installed fibre equivalent or with PIR type boards. If you are getting into that then removing the studs and boarding the entire wall with PIR is potentially a much easier job, but may impact how you will hang cabinets ets as they will need to pass through the insulating to reach the brick. But fitting PIR between wonky battons is a woeful job to do properly.