Internal Insulation

[martin53]

I have a 1905 single brick skin semi and want to insulate the inside of the non-party external walls. I realise this could be a big job so plan to try one room and learn from that.
My plan is to use an insulated plasterboard (e.g. Kooltherm K17) with a dab application direct to the current plaster - I will follow manu's directions. Will likely use 72mm thickness board. My questions are:

1. Should I remove the current plaster? - a lot of work but would presumably give me 3/4 in extra to play with around the window trim - luckily no door on this first wall.

2. The window surround protrudes 1 inch and the cill 2 inches from the wall so even with removing the plaster I will need to extend these. How is it best done without replacing whole cill?

3. Should I remove the window reveals to insulate them - probably to avoid heat bridging? There is enough space around the inside of the window to accomodate the insulation and replace the wooden reveal if i do this.

Typically I jump into dyi jobs and then find the problems so any help gratefully appreciated.

Thanks Martin

 

[noseall]

1. remove existing plaster. unless you are supremely confident of the bond of the existing plaster to the masonry or indeed the integrity of said plaster, then forget it.

2. remove the whole window board and start again. why spoil the ship.....

dab a piece of plasterboard to the horizontal brickwork first. once this has set fix the window board to this plasterboard with a cartridge type adhesive. easy and no fixing holes visible. i use a product called "sticks like s**t".

3. yes do as you say and insulate. unless of course, you want to run the risk of condensation and ultimately black mould?

 

[sim17]

I've just done two rooms the same sort of job. not a professional but wanted to learn by doing, and I've certainly learned a few things.

1. If the plaster is at all loose or degrading, hack it off. If it is solid then dab onto plaster works. Remember the insulated board should have fixing screws finally too, at least 2 for fire regs, but you could put say 6 per board in, in the taper of the board edge. Decent plasterer skim worth it (rather than seal and decorate the board direct). I did one wall part plaster off ie hack away a couple of strips per board, dab mroe adhesive there and thinner blobs on the plastered bit. That worked and can help get the board on level. I used Gyproc Thermaline 60mm. Gyproc details say use their own special cartridge sealent/adhesive if going on to plaster, dry wall adhesive onto brick. Aperture smaller on plaster in their spec. Thermal properties slightly different. But the board supplier told me just use smaller dabs of adhesive just as good, the sealant is so expensive.

2. I thought I'd extend the cill but to be honest it would have worked out less bother if I'd ripped it off completely to start with. Neater job in the end (what I did with 2nd room).

3. Yes, remove reveals and insulate. This is better for the skim work too since the plasterer can continue into the reveals. I left one window with wooden reveals and it turned into a fiddly job decorating and making neat. Had to put back original architrave to cover edge of plastering into wooden reveal extended further out. If your house is old and has lead paint you are saving yourself an awkward job stripping by removing them too!

Incorporating services like sockets is fiddly and needs some thought, so if you can avoid it is better. Any T&E cable should be behind metal conduit or capping (to protect from insulation material). Quite a bit of effort needed to baffle and seal around the service opening.

If at all possible try to continue insulation below floor boards on wall, and above ceiling too (in the space between floors), any coving will need to come off for the board anyway, you might be able to get at the wall gap between floors better by lifting a board or two upstairs.

Most messy and boring bit? Mixing drywall adhesive! If they sold that stuff ready mixed I think I'd cave in an pay a premium for it. So the specialist sealant/adhesive cartridges on plaster might work out well if time is more precious than doing the cheapest job poss.

 

[noseall]

the post is a year old.

gotcha before breezer does.

 

[sim17]

I'm a slow worker...