Internal wall insulation in a flat

PawelK

Hello.

I am hoping someone can assist with some experience sharing. I live in a block of flats and mine happens to be end of the block. Having my bedroom's wall as well as living room one facing that end which is also north facing is terribly cold. I can live with that in the living room but my bedroom has a built in wardrobe on that wall, covering air vent (previous owners must have been not very clever). Even when I keep the door open every time I walk in to the room it feels few degrees colder and there's a smell of damp in the air. My plan is to remove completely the wardrobe, insulate the wall which to my understanding is a solid wall (worse case than with cavity apparently) and hopefully no need to plaster, just paint with anti mould and no wallpaper. What insulation material is the best, most cost effective as I saw great difference in prices but read the best for solid walls is at least 100mm insulation. Should I also source materials and do the while thing now or wait until it gets warmer? Any other things to consider would be greatly appreciated.

Thank you and apologies for any typos.

Doozergirl

You can use insulated plasterboard. You don't necessarily need 100mm - that the old standard for rockwool insulation. You can never have too much, but good insulated plasterboard features a solid insulation like Celotex which is more insulating and so you don't need the same
thickness to achieve the same U value.

Have you checked that the radiator you have in there is sized correctly? You can do a BTU calculation here:

https://www.bestheating.com/btu-calculator?gclid=EAIaIQobChMIvtiWyZr_5gIVh-FRCh146gxsEAAYASAAEgI2FvD_BwE&gclsrc=aw.ds

Also check that the radiators are balanced properly. It might be that you don't need to insulate.

Are you putting wardrobes back in? Presumably that's why you don't want to plaster? Otherwise it sounds a bit weird.

choille

If the damp is due to lack of ventilation then you need to address that. Sometimes it can be caused by condensation eg if you have a shower and the steam is condensing on the coldest surface it will create mould.

FreeBear

Doozergirl wrote: »

You can use insulated plasterboard. You don't necessarily need 100mm - that the old standard for rockwool insulation. You can never have too much, but good insulated plasterboard features a solid insulation like Celotex which is more insulating and so you don't need the same
thickness to achieve the same U value.

The minimum requirement is 0.30 W/m²K for external walls when doing a refurbishment. 75mm of Celotex/Kingspan will (just) exceed this value. If you use a warm batten method of insulating, the total thickness will be 125mm - That is a 25mm air gap, 75mm of insulation, 12.5mm plasterboard, and a nominal 3mm skim of plaster. You could use an insulated plasterboard (normal plasterboard with a layer of rigid foam insulation bonded on) and stick it to the walls with something like Dow Insta Stik. It would be quick, but not necessarily cheap. And 2.4m x 1.2m boards are heavy and need two people to move them. Attention also needs to be paid to sealing between the boards, ceiling, floor, and around any windows.

Check your lease to see if this type of work is permitted or if it requires permission first.

I'm in the middle of insulating the solid brick walls of a small room. Even although the work isn't finished yet, having the insulation boards up has made a huge difference in there. The temperature is hitting 19-20°C, and I haven't got the radiator fitted in there yet.

[Deleted User]

This keeps coming up, I am going to start having to ask the company for commission lol (joke).

I had a similar problem with cold walls in a bedroom and mould. The walls were one brick thick and at the back of the building where the sun never reached. I was told it was a lifestyle problem but I always kept windows open (do like fresh air anyway).

So I bought some insulating wallpaper. Its supposed to be like adding a layer of concrete blocks to a wall. I have to say the room was instantly warmer, the walls felt warmer (they were always colder than walls in the front of the house before I did this but this was ignored when the property was inspected). I cleaned the mould up before I put the wallpaper up (used vinegar as it stays on the wall for a while) and it never reappeared. Never had a problem again. However I would advise keeping wardrobes away from the wallpaper until you are certain the problem is solved.

This is the brand I used, but I also used the special glue which is suppposed to add to the effect - it smelled like a pva glue so you might be able to get away with simple pva glue. https://www.gowallpaper.co.uk/saarpor-graphite-insulating-lining-paper-single.html You also have to be careful to not damage the edges of the wallpaper although I am sure you can fill any slight dings you make.

PawelK

Thanks everyone for this extremely valuable information. I will definitely not be putting back any wardrobe in there. Considering open railings style or much smaller self standing wardrobe on the less problematic part of the wall (away from the windows). Hopefully removing old wardrobe won't be a big issue as there is a glass cupboard, a mirror and lighting with it.

pattypan4

we did the internal insulation in a freezing cold single skin bedroom over a garage. It was a very large room and we had space to spare. DH put batons on the wall and and then plasterboard. It made a huge difference. The air gap acted as insulation

markin

deannatrois wrote: »

This keeps coming up, I am going to start having to ask the company for commission lol (joke).

I had a similar problem with cold walls in a bedroom and mould. The walls were one brick thick and at the back of the building where the sun never reached. I was told it was a lifestyle problem but I always kept windows open (do like fresh air anyway).

So I bought some insulating wallpaper. Its supposed to be like adding a layer of concrete blocks to a wall. I have to say the room was instantly warmer, the walls felt warmer (they were always colder than walls in the front of the house before I did this but this was ignored when the property was inspected). I cleaned the mould up before I put the wallpaper up (used vinegar as it stays on the wall for a while) and it never reappeared. Never had a problem again. However I would advise keeping wardrobes away from the wallpaper until you are certain the problem is solved.

This is the brand I used, but I also used the special glue which is suppposed to add to the effect - it smelled like a pva glue so you might be able to get away with simple pva glue. https://www.gowallpaper.co.uk/saarpor-graphite-insulating-lining-paper-single.html You also have to be careful to not damage the edges of the wallpaper although I am sure you can fill any slight dings you make.

Sounds like black magic to me, i notice they don't say what the Uvalue of 26cm of concrete is, its not much is it! You can have a 2 foot solid wall and it will still be cold. I'm sure its just as good as the tin foil type.

"Graphite Insulating Lining Paper delivers 20% better insulation performance than standard insulating lining paper. This is equivalent to having an extra 26cm of concrete on your walls over and above an insulating lining paper."

Even 3cm of kingspan would be far better.

[Deleted User]

You may not believe in the remedy, but it does work. I don't believe in black magic either.

As I said in my original post, I touched walls in my house before doing this, the walls in the affected room were cold relative to the walls at the front of the house. The walls after applying this paper were not cold anymore. I had a builder do the same, he found the same thing, not my imagination. It was him that recommended the wallpaper. He wasn't looking for a job, he knew I couldn't afford a professional.

That's not reflection, thats insulation.

ComicGeek

All that lining paper does is reflect a bit more heat back into the room than if it wasn't there, thereby making you feel slightly warmer through effects of radiation. For me it falls into the same dodgy sales tactics as insulating window blinds and thermal paint.

Better than nothing, but nowhere near as effective as 50-75mm of proper insulation. Don't worry if you can't get the full 75mm of insulation, even 50mm of good quality insulation is going to reduce heat loss through the external wall by up to 75%.

FreeBear

ComicGeek wrote: »

Better than nothing, but nowhere near as effective as 50-75mm of proper insulation. Don't worry if you can't get the full 75mm of insulation, even 50mm of good quality insulation is going to reduce heat loss through the external wall by up to 75%.

Just to crunch a few numbers (the higher, the better)...

260mm of reinforced concrete will have a thermal resistance of 0.113 m²K/W
4mm of polystyrene (a.k.a. thermal wallpaper) ~0.11 m²K/W
50mm of polyurethane foam (Celotex/Kingspan type boards) 2.17 m²K/W
75mm of PU foam 3.26 m²K/W

So whilst the thermal wallpaper will do something, it is no where as effective as 50mm of foam. To meet current building regs, 75mm would be the minimum. The downside to using too little insulation is that the dew point could end up inside the wall - This becomes a problem with (interstitial) condensation and damp gets trapped in the wall. The small room that I'm refurbishing had been insulated on the walls with 5mm of polystyrene. On stripping the walls, I found the plaster to be soaking wet and falling off the wall in places. Really not good...