insulating dormer walls

mug51

Hi,

I have a dormer bungalow that is sooooo cold in the Winter (turn CH off and go to bed at 21 degrees, wake up 8 hours later at 5 degrees), so just before Winter returns, my bedroom needs insulating. I have just created an access in the knee wall and I have attached some pictures.
Under the dormer window and also my access to the inside of the other knee wall
The back of the wall that is so cold in the Winter.
The roof that is opposite image 2, rafters are 70mm deep
What it looks like when I crawl through the access hole (will call it a hatch when I put a door on it), bedroom wall on the left and the sloping ceiling above the stairs in front. Roof on the right
Sloping ceiling that leads to the attic, will make this a primary access to the loft, current loft hatch is 200mm x 300mm and the slope of the roof is 100mm from it.

As you can see there is no insulation other than the heap of wool and the strip of insulation roll.

The battens are 70mm deep behind the walls I want to insulate. I was going to stick 100mm celotex boards to the back of this wall but that will not be an option, maybe 70mm boards fitted between them? Is that enough?
The wall is made from wooden laths and plaster can I push insulation board up against the back of that wall or will it need a gap?

I will also fill the voids between the floor and the downstairs ceiling with wool, and insulate with wool along the top of the living room ceiling (that can be seen in image 1), or would boards be better?

Is there a better way to insulate than what I have mentioned (assuming what I have mentioned are all suitable ways to insulate)?

Thanks,
mug51

FreeBear

You'll probably find the nibs of plaster overhanging the laths will prevent you from fitting 70mm boards flush with the studs. What you could do is to use 50mm or 60mm boards between the studs and then fix another layer of full sheets across the studs. Might also pay to put some Rockwool batts between the rafters while you are in there.

mug51

FreeBear wrote: »

You'll probably find the nibs of plaster overhanging the laths will prevent you from fitting 70mm boards flush with the studs. What you could do is to use 50mm or 60mm boards between the studs and then fix another layer of full sheets across the studs. Might also pay to put some Rockwool batts between the rafters while you are in there.

good point on the nibs of plaster, totally forgot about factoring those in, thanks.

yeah, I was thinking about boards over the studs but was not sure if the studs needed to breathe or not, although thinking about it loft insulation goes over the joists as well as between so I guess it will be fine.

bmthmark

Not sure if its suitable but I've seen tlx silver insulation used in lofts:
http://www.jewsontools.co.uk/tlx-silver-mulitfoil-roofing-insulation-1-2-x-10m-roll.html?utm_source=google_shopping&gclid=COTpqNfBjs8CFciRGwod4WICfw

If you can get celotex boards in then attach tlx silver over the top. Worth looking in to