Insulating interior walls, is it worth the hassle?

Thanks for the input guys, I appreciate it. I have decided to go for 40mm Celotex foil backed board and then baton the wall out with the insulation in between, then use some PVC tile effect cladding over the top. It doesnt look as good as tiles but i'm hoping it will add a bit more insulation with it being hollow and also it will be easy to clean and keep it looking good.

Also going to rip the floor up and then put a 80mm insulation board down and then put some 18mm OSB T&G flooring on top to create a floating floor. I think this will work out cheaper and be a lot easier than laying another concrete floor.

Then the rest of the boards I will cut up and slide down between the rafters in the roof as this house is designed so badly the roof actually forms part of the ceiling in the bedrooms, so that area of the roof in about 100mm thick and uninsulated. The rest of the loft I have put 270mm of rockwool down.

If after all that it's still cold I will move out lol.
 
Mark A said:
Bit of an update, I took some bricks out and the cavity was filled with rubble about 2" higher than the floor level. Could this have been bridging cold from the outside stone wall, to the inside brick and then the concrete floor?

Also I broke some of the concrete floor and it appears that they haven't insulated it :mad:. I don't know what to do now. Its only a small room so I guess it wouldn't be too hard to remove all the concrete and dig it out a bit more to put some insulation under the floor. But is it actually going to make a big enough difference for all the effort?

[IMG/]http://i29.photobucket.com/albums/c...om/albums/c267/ashworth614/DSC_4338.jpg[/IMG]
As you can see its about 50mm of concrete with no insulation in sight.
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After seeing this buddy! Get it done as soon as you can. It might be worth getting it done with the wall cavity foam. Your walls get drilled into and tested then squirted with liquid foam, which hardens and creates a nice shield.
 
mrbell1984 said:
After seeing this buddy! Get it done as soon as you can. It might be worth getting it done with the wall cavity foam. Your walls get drilled into and tested then squirted with liquid foam, which hardens and creates a nice shield.
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We were told that due to the fact our outside skin is random stone that cavity wall insulation wont be possible :(. I think its due to the fact the cavity isn't uniform in size and the foam might end up creating cavities that could then create cold spots. That would have been great if it could have been done as it would have made the house so much warmer and could have been done for free.
 
Mark A said:
If after all that it's still cold I will move out lol.
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Try our place. All walls are external and no cavity walls (way too old for that luxury). A couple of rooms are a nightmare to keep warm with the central heating. Thankfully they can be heated with open coal fires in winter.

Looked at internal insulation. Far too expensive for the return it would give. Out energy saving double glazing in and insulated the loft properly. That's helped but she's a cold house at times. I snuggle up with the wife. Works a treat.

mrbell1984 said:
After seeing this buddy! Get it done as soon as you can. It might be worth getting it done with the wall cavity foam. Your walls get drilled into and tested then squirted with liquid foam, which hardens and creates a nice shield.
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Perhaps you should have read his post above? :p
 
Mark A said:
We were told that due to the fact our outside skin is random stone that cavity wall insulation wont be possible :(. I think its due to the fact the cavity isn't uniform in size and the foam might end up creating cavities that could then create cold spots. That would have been great if it could have been done as it would have made the house so much warmer and could have been done for free.
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ah what a shame :(
 
wallinsulationplan.jpg


Just wondered if anyone could help as I can't seem to find an answer after searching google for hours. I have bought 10 sheets of 40mm Kingspan and plan on putting it between batons and then putting a pvc tile effect cladding over the top. I'm just a bit worried about condensation forming on the brickwork behind the insulation and also the timber batons creating cold bridging.

Was thinking of putting the batons flat so that there is about 10mm gap when the insulation goes on, then filling the gap with polyurethane expanding foam and then putting some aluminium tape over the join to create a vapour barrier. Does this sound right or should I be adding some sort of vapour layer?
 
Line the brickwork with vapour check layer

You won't get a cold bridge from timber, don't leave a gap under the plasterboard it'll snap or heads will pop out the skim
 
Could you possibly link me to a product I should be using, I'm guessing this stuff http://www.wickes.co.uk/polythene-vapour-barrier-25mx20m/invt/153230/?source=123_74? I was hoping the silver foil on the insulation would act as a vapour barrier, but if you think I should add one then I'll do that as I want it to be right.

Is it just a case of trapping it behind the timber batons so that its touching the brick wall, then the insulation boards on top?

Thanks :).
 
Bit of an update for anyone interested and another question.

Firstly I have battened the wall and put 40mm Kingspan boards in between and foamed up any gaps. I'll put aluminium foil tape over the batons to totally seal it up, then plasterboard.

It has made a big difference already. Even with the rad removed the room is warm, whereas before it was cold with a rad in there. I have also bought a slightly bigger rad as the one that was there was a tad too small according to online radiator size calculators.

So thanks a lot for the help as I probably would have just left it believing it wasn't worth it.


I would like some advice on what to do with the floors though as these are still freezing cold.

I noticed that there was condensation on the floor in a 3" strip next to the back door. I chipped up the floor and the self levelling had cracked in a line and upon removing this it looks like the stone cill goes through to the inside and they have just concreted up to the stone cill. So this will be bridging cold through to inside and explains why the floor is so cold. It is also damp in the corners, which i am hoping is just due to the condensation getting under the floor tiles.

What would be the best thing to do here to insulate it? I was thinking of putting down 25mm insulation board above the concrete on top of a DPM and then putting an 18mm ply board on top as a floating floor with vinyl. But now with the damp I'm not so sure its a good idea and might be better ripping all the concrete out?

IMG_5514.jpg


Anyone know how much it would cost for a builder to lay a 1m x 3m concrete floor with insulation under it?
 
The foil on the board is a vapour barrier, so you were OK on that, a continuous membrane is better but the room isn't a bathroom so no big deal.


The floor should be dug up to say 6 inches, if the ground is rough then a 25mm layer of sand, the blue plastic damp proof membrane put down and up along the walls (like your mother lining a baking tin with waxed paper), then a sheet of 50 to 100mm of Kingspan horizontally, a continuous vertical perimeter of say 50mm** Kingspan (like making a box), then topped up with 3 inches of concrete to just below floor level, levelling compound for the last 5mm.

The idea being is that the concrete slab stays insulated from the surrounding ground layer and is warmed by the room like a big heat sink.

Some pictures:
http://www.kingspaninsulation.co.uk...-4622-97bb-5861799ab02a/Thermafloor-TF70.aspx


Roughly 15 bags of concrete & ballast, £75 approx.

It's a really easy job given that you have already battened the walls.


**the width of Kingspan here should match the depth of the battening, so probably around 50mm.
(so really the floor should have been done first as it's easier to access ;))
It doesn't have to be 50mm all round, 25mm will do by the door, it's just that concrete can be trodden on and insulation can't.

'
 
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bitslice said:
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Yeah I should have left the walls for now, but i was originally going to put down a floating floor, doh! The insulated walls are just the 2 external walls and I have left it shy of the floor by about 70mm, so should still be able to get in.

So would you say this would be a better approach than insulation over the top? I could do it quite easy as the slab the council have laid is only 50-70mm thick and I have a breaker. The only thing I'm not sure about is that big stone door cill (sill?). It comes into the room by about 3" and looks to be about 8" deep. It seems to be in line with the foundation so probably not a good idea to start cutting it down?

EDIT: Also, would 2 sheets of 40mm Kingspan TP10 do as the insulation, or should I get a single thicker sheet?

Thanks :)
 
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Mark A said:
So would you say this would be a better approach than insulation over the top? I could do it quite easy as the slab the council have laid is only 50-70mm thick and I have a breaker.
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Well under the 50mm slab is just going to be hardcore I'd imagine, so easy to dig out (doesn't have to be an archaeologically perfect excavation, just as long as nothing sharp tears the plastic damp proof membrane )

From that .pdf you'll note there are two ways of doing this:
.slab, insulation on top, screed
.insulation underneath, slab, screed

I prefer the latter (concrete in an insulated box), the depth is the same and the concrete acts as a heat store, regulating the temp of the room. The former doesn't use the concrete as anything other than a dumb foundation material. Always think what the Romans would do :)

The only thing I'm not sure about is that big stone door cill (sill?). It comes into the room by about 3" and looks to be about 8" deep. It seems to be in line with the foundation so probably not a good idea to start cutting it down?
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You'd possibly have problems cutting a stone sill because of the angles involved, but it's not doing anything structural so you can if you like.
As you've noticed, it's certainly going to be cooling the existing slab, so insulating a new slab from the outside wall is important.

EDIT: Also, would 2 sheets of 40mm Kingspan TP10 do as the insulation, or should I get a single thicker sheet?
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Yep, doubling up is fine, eBay is a good source for offcuts of Kingspan as are skips and building sites. Having a jigsaw of pieces makes very little difference. Polystyrene slab is almost as good for this application.

The council is a bit naughty only using 50mm of concrete (surprise!), but it is a low traffic/load area so you could skimp on the depth of concrete yourself, 50mm is a minimum though. Less water creates a harder mix.

The problem with floating floors and insulation on top is that it is trashed if you have a water leak, then there are issues with condensation/damp, lack of ventilation to the air space. This is the problem when builders don't get it right first time (or ever in fact).
If any copper pipes need to pass through the concrete slab, wrap them in split foam, concrete corrodes copper.
 
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Just seen this topic again. Watch the type of insulation you're wanting. The kingspan tp10 is for sloping ceilings. For the floor use tf70 and walls tw55.
 
Derek W said:
Just seen this topic again. Watch the type of insulation you're wanting. The kingspan tp10 is for sloping ceilings. For the floor use tf70 and walls tw55.
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Are they not the same? When I put TF70 into ebay after looking at that PDF bitslice posted, it came up with most listing TF70/tp10 as though they were interchangeable. They also all say uses include under screed, cavity wall, flat roofs etc.

TW55 finds nothing on ebay. EDIT: TW50 finds cavity boards, but they look the same as what I have got here, which is the light yellow polyurethane rigid foam which is foiled on both sides. Could these be specially made size for cavity wall applications so that they slot between the wall ties? Mine are big sheets of 40mm which i was told would be fine for both under screed/concrete and also for use in between battens for insulating an interior wall.
 
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maccapacca said:
Line the brickwork with vapour check layer

You won't get a cold bridge from timber, don't leave a gap under the plasterboard it'll snap or heads will pop out the skim
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^^This
Especially if your room is an add on to the original building, like a kitchen or toilet other wise you will eventually get mould build up as most lower floor add on buildings tend to be single brick course and suseptable to damp
 
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