Insulating solid walls internally

[David937]

Hi there,

Our house is a fairly old (1930's I think) 3 bedroom + loft conversion semi detached house with solid walls. In winter the house is absolutely freezing and as soon as the heating is off it gets cold VERY quickly.

With this in mind we would like to try insulate the solid walls internally and we are hoping this would make a difference, is there anyone on here who has done it and noticed the difference?

The plan is to try it out in the smallest bedroom upstairs which has 2 smallish external walls, one with a window. I would look some pointers on the best way to go about it, we would not like to loose too much space in the room but would like the best efficiency possible, I guess we have to strike a compromise in reducing room size and effectiveness.

I understand the process is something like this:

Fix battens to wall - fix a plasterboard to the battens (this plasterboard has presumably some insulation and foil backing?)

Or is it better to fill the airgap with something like rock wool before boarding over?

As you can tell I'm not really clued up on how to deal with preventing damp, whether to fill the gap in or not?

The room in question also has a 'hit and miss' ventilator high up on the wall which is closed permanently.

There is no damp problem anywhere in the house.

I would really appreciate some suggestions as I'm not quite sure how to start.

 

[accelerator]

Out of interest, is your loft already well insulated? I'm no expert, but I would guess that needs to be done first.

Rgds

 

[David937]

Out of interest, is your loft already well insulated? I'm no expert, but I would guess that needs to be done first.

Rgds

Indeed it is, it's used as a bedroom now, carpeted over, cupboards, bed etc.

 

[r896neo]

have a look through some old threads using the search function as this topic has been discussed at great length. also the major insulation companies will all have good technical guides which can be viewed or downloaded on their websites

 

[David937]

Thanks.

Having read a bit, its a matter of fixing the timber battens to the wall, filling the gap with rockwool, putting a vapour membrane over it and finally screwing in Kingspan K18 board?

 

[Deluks]

19-22mm for the battens, no space for rockwool. Go for the max 62mm K18 if you can afford to lose the space.

 

[ajrobb]

I don't think you want a vapour barrier on the cold side of the Kingspan K18 as that will just trap condensation. Besides, K18 is itself a vapour barrier.

Another alternative is http://www.celotex.co.uk/Applications/Wall-Insulation/Solid-masonry-walls-Internal - they have PDF guides to download. This has the advantage of a service void behind the plasterboard. Also, the battens don't need to be treated.

 

[David937]

Thanks a lot guys, next project will be insulation here I think

The PL4000 option is very interesting and probably what I will go for.

 

[foamit]

Dob & dab Insulated plasterboard on internal walls, no battons requred less floor space lost

 

[David937]

Dob & dab Insulated plasterboard on internal walls, no battons requred less floor space lost

Dob and dab eh

Yeah, it seems a nice solution.

 

[ajrobb]

Dob & dab Insulated plasterboard on internal walls, no battons requred less floor space lost

Well, that came out of left field...
I thought we were talking about internal insulation of external walls. I think Kingspan K18 is designed for batten fixing to solid walls. Refer to http://www.insulation.kingspan.com/uk/pdf/k18.pdf

Dot'n'dab is not recommended by Kinspan for solid external walls, although they do recommend it with K17 for cavity walls.

 

[David937]

Ah, these are external walls we are insulating....

 

[digdilem]

Yes, done it to a "Park home" caravan which had 20mm of rockwoll between aluminium walls.

The difference was astonishing and turned a very uncomfortable caravan into something very livable.

I used insulation-backed plasterboard. Fairly easy to fit. Enough slack on the electric fittings to just bring them forward. Refit arcitrave and skirtings, make the window reveals a little deeper. The caravan had air vents which we preserved, but the room I did later didn't and went straight onto the existing wall with just the basic prep.

Not cheap but very effective. Also used the same stuff for ceilings and direct onto blockwork with dot and dab (the expanded foam acts as a vapour barrier too).

The stuff I used was (I think) Thermaline Plus, 45mm. Easy to work, easy to fill where you got it wrong, perfect painting surface when done.

 

[mbga9pgf]

Sorry to hijack the thread. I am looking to stud out using 2X2 pressure treated batten, infilling using Celotex 4070 and capping the battens with strips of 20mm thick Thermal barrier. Joints will be all taped closed to provide a vapour barrier. I am then planning on Screwing down Standard plasterboard (no vapour lock) through the 20mm thermal capping to the 2x2 batten. The plasterboard will be flush (no airgap) with the celotex.

Anyone see a problem with the above plan (damp etc?) ? The plasterboard will be in contact with the vapour barrier.

Finally, I need to seal around the window sills, as they will now be protruding 70mm due to the celotex. I dont have much space to build inside the window recess due to the double glazing; do I need to insulate round the windows recess or can I use ply and paint?

 

[sjroberts1]

Hi, I know its an old tread but was wondering how you got on, I need to be doing a similar job to an old farm house on external walls. Built a new house in the last few years and used 2" celotex, would this be enough for the renovation.
Cheers

Steve