Insulating monocrete - from the inside

Another insulation question, but none of the previous ones have given precisely the info I need.

I have a house that is partially made of monocrete. For those not familiar (ie you dont live in Canberra), these are pre manufactured concrete slabs about 1.5m wide which are bolted together to form the house. On the inside its just the concrete, no plasterboard is attached. In terms of insulation monocrete rates roughly just above the R value of a window.

My son's room faces E/S, and has 2 external walls of monocrete. When it gets cold, just like with a window, there is about 1-2ft of cold air just sitting next to the walls. The rest of the room is a bit cooler but not too bad - central heating.

I am thinking of insulating the wall. Ideally I would built a frame on the outside of the wall and insulate that, putting brick veneer or something as the external barrier (the newer part of the house is brick veneer anyway). However, that is a fairly largish job, plus for one wall it would impact on the window of an adjoining room and on the other would need to be extended all the way across the front of the house to avoid having a 'step' in the wall (the other part of the house is a second living room, so if it gets cold at 3am its not a problem). In other words, once I start I almost have to build around the whole house.

The cheapest option is to hang a heavy drape over the wall, but apparently this isnt aesthetically pleasing! Or to put another heater in the room and just keep the temp up - using the central heating to make this room warmer would make other bedrooms too hot.

Anyway, I was thinking of building a fake wall on the inside of the room - insulating in between. Essentially building a wooden frame and attaching it to the inside of the wall and putting plasterboard over the frame. The problem is that the room is not particularly big, so I wanted to keep the distance between the current wall and the fake wall as small as possible.

Bulk fill seems the most appropriate, but it takes up a lot of space so I was wondering whether silverbatts or maybe foilboard might be more useful. Or even a hard polystyrene board that could (?) just be glued/fixed to the monocrete and have (presumably) plasterboard in turn glued to it.

Questions:

1. does anyone have an opinion on the best type of insulation - the cold entering the house in winter is the main problem rather than heat entering in summer (since the room faces away from the sun). R-value as high as possible, of course, but realistically around R1.5 is fine - enough to take the cold air barrier away. Aim is to use as little space as possible with the fake wall (which also helps the windows from looking odd from being packed excessively)

2. would there be a need to put on a moisture barrier? I don't quite get where I could drain the condensation away to, given that any barrier would just reach down the the floor and I don't want the water to be draining away onto the floorboards/carpet.

thanks in advance

ctd

Your problem is not cold getting in but heat getting out. (I know it's a technical quibble)

If it were a glass window, you could double glaze the glass or stick an insulating film on it. An insulating film reflects heat back into the room rather than letting it out through the glass.
In theory you could do the same with the wall, i.e. apply an insulating film to the inside, which would then be painted.
I suggest you do a bit of google searching.

You could also insulate the outside of the wall. Rather than brick veneer, you could attach batterns to the external wall, glue styrofoam in the "bays" and then cover the lot with fibre cement sheeting — you would potentially only increase the wall's thickness by 60mm — and the external finish would be very similar to what you now have.

ian

I'm not familiar with monocrete, but am very familiar with Canberra winters.

1. There are paints which claim to have insulating properties. At least one apparently contains ceramic beads. Haven't used any so can't comment on their effectiveness.

2. You might consider a wall sized notice board useing Caneite, which has good insulation properties and is fairly inexpensive. Pins manage to pull bit of Caneite out so a notice board works better when covered with material. Hessian would suit in a boy's room and is fairly wide. Spray the finished wall with fire retardant.

3. There is an exterior cladding system I came across on the net - designed with fibro houses in mind. A wire mesh is fixed to the wall, sprayed with a foam product and then rendered over. Manufacturer claimed it had excellent insulation properties. Unfortunately, can't remember what it was called or how I found it but it looked really good in the photos. Perhaps someone else on the forum might point you in the right direction. "Tarting up fibro house" didn't work too well on Google.

The system can be used over just about any finish - fibro, brick, etc. - but it didn't seem to be a DIY job.

cdt
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