IWI- how to tackle party or internal walls

[mh12]

As the title suggests how is the return of the insulation on the inside/party walls tackled. The following you tube recommends a tapered insulation on the internal walls to about 600mm.

Other option would be to have similar thickness of insulation to that applied on external walls to about 600mm on the adjacent internal walls.

This would look a bit odd. Rooms with stepped walls

For those members who have gone down the rout of IWI - what did you do with the returns, if anything?

 

[Kearn]

I really can’t visualise the challenge here?! And it’s really annoying me!

I guess to some extent’s it depends on what the insulation is and how it’s fixed, but wouldn’t it just run along the external wall and butt up against the perpendicular internal wall?

Why the need for tapers or steps?

 

[Kearn]

Ok, I gave in and watched that funny old chap.

He’s one of those dangerous folks who drops a few buzzwords in regularly enough for people to believe he knows what he is up to…

IWI is proving to be such a minefield. There is so much challenge to it and every situation is different.

Cold bridging through a party wall/internal partition. I personally wouldn’t be worried about it. Certainly not enough to create an ugly intersection as you say, which I doubt would make a noticeable difference.

 

[LadyArowana]

No wonder the chap is cold he’s wearing a thin cotton shirt, if he put on a decent thermal vest and a proper woolly he could stop bothering about sticking stuff on his walls

 

[montyjohn]

Cold bridging through a party wall/internal partition. I personally wouldn’t be worried about it. Certainly not enough to create an ugly intersection as you say, which I doubt would make a noticeable difference.

My plan, although not gone through LBC with it yet so may not be possible, was to remove 300mm of plaster on the internal walls where it meets an external wall. Replace that plaster with wood wool (20mm for example) and then lime skim over it.

Not brilliant, but hopefully enough.

 

[fernicarry]

Cold bridging through a party wall/internal partition. I personally wouldn’t be worried about it.

If you imagine being stood in from of the insulation near the middle then no matter what direction you go towards the outside you have to pass through the full thickness of the insulation. But if you are close to the end then in some directions you won't pass through the whole depth. So the effectiveness of the insulation against the outside wall tapers off as you move towards the junction with an uninsulated element. If that's a corner then you get a cold spot right where you least want it. I wouldn't call it cold bridging as there is no bridging element.

As for the stepped return, nah, that's way too ugly, I haven't done it. Tapered sounds even worse as the change in direction at floor and ceiling level would be really obvious. Since the external walls here are hollow I try to tuck the insulation in beyond the partition studwork. Its a bit of a token gesture. Maybe one day all my little bits of IWI will join up to make a continuous layer...

Its the same reason you carry wall insulation below floor level and above ceiling level.

Replace that plaster with wood wool (20mm for example) and then lime skim over it.

A strip of aerogel bedded into the return wall would give you plenty of performance. Its expensive but you wouldn't need much of it.