Internally insulating a small flat roof

[bob the biscuit]

Hi

I live in a 70’s bungalow and the living room has a 3’ square bay window which has a flat roof. Last year we had cavity wall insulation installed and now we are decorating the lounge we are concerned that a great deal of heat will escape via the flat roof. I realise probably the best thing to do would be to remove the plasterboard, insulate and re-plaster, but I was wondering if there was any type of insulation I could apply to the existing plasterboard and then wallpaper over the top?

Thanks in anticipation.

Bob the biscuit

 

[nstreet]

You can get polystyrene backed wall paper or rolls of thin polystyrene about 2mm thick for a few pounds, which you apply like wall paper.
This may give some insulative qualities. If you sandwiched the polystrene between a layer of foil backed plasterboard and your existing plasterboard it may do the trick. Then again the whole exercise may end up costing more than the amount of heat you are losing.

 

[noseall]

insulation backed plasterboards are available.

there are varying grades and thicknesses available, but are un-weidy and difficult to handle even on a wall. nigh-on impossible trying to fix to a ceiling whereby the joists aren't visible.

i would suggest removing the existing ceiling and using 97mm kingspan or cellotex between joists, along with another 25mm layer across the joists.

then plasterboard and skim.

at least this will be up to speed with reg's and give you the opportunity do install any electrical alterations.

 

[noseall]

thinking about the above advice.

as the existing flat roof void is probably not ventilated it might be an idea to full fill the ceiling void.

 

[bob the biscuit]

thinking about the above advice.

as the existing flat roof void is probably not ventilated it might be an idea to full fill the ceiling void.

I was wondering that too Noseall. Do you think I could I use something like this?

http://www.absealants.co.uk/product_34-5-34_Bondseal-Expanding-Polyurethane-Foam-500ml.htm

 

[Robbie uk]

Before i read the above thread i was thinking the same thing. Drill a small hole into the plasterbaord and pump the foam into the void, as this will expand about five times it might work.

 

[salem2000]

Before i read the above thread i was thinking the same thing. Drill a small hole into the plasterbaord and pump the foam into the void, as this will expand about five times it might work.

But if you pump in too much,when it expands it will then push the plasterboard down.

I go with what "noseall" said, remove the plasterboard and insulate the void with Kingspan or celotex. Do not use polystyrene where it may come into contact with any cables as it can react with and degrade the insulation.

Salem.

 

[joe-90]

I'd use the spray foam. It won't push the plasterboard down but it will fill the void.

 

[easybuy]

We have just converted garage to bedroom with ensuite and had similar problem, was advised by building regulations to put 150mm mineral insultaion, foil back plasterboard covered by plastic membrane.

Just had the all clear this week! Goodluck.

 

[salem2000]

I'd use the spray foam. It won't push the plasterboard down but it will fill the void.

I beg to differ. have seen it used to infill a void above a bathroom doorway which was once glazed. Leveled with plasterboard each side, later expanding foam was injected for soundproofing, the following day a noticable bulge was showing on both sides of the plasterboard panels and one side had partly blown away from its fixings. Result was to remove and redo all work, with insulation and re-skim.

Salem.

 

[joe-90]

Don't overfill it then.

 

[joboatbuilder]

If you really want to use expanding foam this might help avaoid plaster board bulges....If you drill enough holes with a hole saw the excess foam will escape. You'll have lots of holes to fill though...
Personally I'd take the plaster board down, I'm no expert though .