Internal insulation and thin framing for plasterboard

[Kaymo]

Hi,
My apologies from the outset if I have terminology wrong etc, but I will try to explain what I am trying to do. Having removed an old, what I think is referred to as a timber stud wall with plasterboard fitted, rather excessively to cover a few pipes that could have just as easily been boxed in, I found an old crumbling lath an plaster wall under that, and an even older plaster layer under that, directly applied to the solid stone wall.

Making use of some of that space I would like to fit insulation boards direct to the wall, loosely held in place, then build a wooden frame to hold the insulation to the wall, fixing to the joists top and bottom, with light plasterboard on the room side. My thinking is that this would keep the battens on the warm side, the cold side is a vapour open sandstone wall.

My questions are does this sound like a valid method, and crucially, how thin could I make those battens?

Thanks.

 

[Kaymo]

Hoping someone out there might be able to offer some advice. To give a bit more detail, the plasterboard wall that I removed was framed in 48mm2 timber, fixed to floor and ceiling and was fairly solid. I am wondering how much thinner I could go before there would be too much flex in the structure, given the distance floor to ceiling is around 2.7m.

I could of course throw something up and test it, but I was hoping someone who had done this before might be able to save me some time and timber if there is a guide to how thin the battens can be?

Thanks

 

[Alastairreid]

Why dont you fit insulated plasterboard straight on to the existing wall?

 

[Kaymo]

I was trying to avoid having timber on the cold side of the insulation, to avoid the risk of it rotting and to avoid any thermal bridges. The frame I took down was installed top to bottom and thought I might be able to replicate this but with thinner timber, giving me the gap without protruding too far.

 

[oldbutnotdead]

If you don't need the studwork (to hang cupboards or whatever on it) then don't bother with it. Get enough insulated plasterboard (or you can make your own with Celotex/Kingspan to whatever thickness you have room for, plasterboard and non-solvent Gripfill) and some board adhesive and glue the insulated boards to the wall.

If you want to go the timber route, 3 x 2 would be about the minimum for that height. You could go 2 x 2 with intermediate fixings to the wall (at 900 and 1800) as well as top and bottom.

 

[Kaymo]

Thanks for the tip. There would be a shower and toilet on that wall so presumably I would need a frame for fixing those, and running the pipe behind.

When you say 3 x 2 is that cm or inches? If inches this would be close to what was there before which was about 2 x 2".

Sorry if I am asking stupid questions, but I have never done this before, and although I will know once I have built it if it is strong enough, i'd rather draw on others experience and do it right first time.

 

[Ian H]

That would be inches but the finished size would be around 68x44mm

 

[Kaymo]

Thanks, sounds like I won't be able to go any thinner than was there before then. Might not gain anything and could be as well to batten to walls and insulate between. Will measure up tonight and see what looks like the best option.

Thanks.

 

[oldbutnotdead]

Toilet won't need much wall support unless it is v posh. Shower- if thats an electric shower then be careful, the supply cable might have to be derated if it is covered with insulation (if it is clipped to the wall and there's an air gap to the insulation you'll be fine).
If your new wall is going to be part of the shower enclosure then use tile backing board or Marmox or anything that doesn't fall to bits if it gets wet (like plasterboard does).

 

[Kaymo]

Thanks. Not electric shower so no cable issues, and using wet wall panel, so shouldn't be the issues with water getting behind.