Help: external wall insulation gone wrong?

[Pobble]

We had external wall insulation fitted to our 1930s semi with solid walls while having it extended. Problem was builders discovered the half bay (which would have had crittall curved steel windows) was cracking above the weak pvc windows. They said that no upvc window strong enough to support the weight of bricks so recreated the curved bay between the upper and lower floors in timber, then added the insulation and then rendered. We did have new stronger windows fitted. Trouble is it leaks, inside, and looks like it is running with water outside through the insulation when it rains. So questions, is something missing to make it waterproof? And can we really not build the bay back in brick? I fear wet rot and dry rot! Any advice on this gratefully received.

 

[martygturner]

There is no membrane between the ply and the insulation...even basic would include some roofing membrane. But I would have expected the ply timber framed outer face to have of below, a moisture control layer that is waterproof from the outside in eg Tyvek membrane. But if it was me I would have put a few sheets of hardibacker in place of the ply and sealed all the joints, then some Tyvek .Good enough for a shower.....

 

[George_engineer]

It was a good spot from the builder as he curved section was an issue. You could have had a curved steel beam put in but that would require fabrication and could cost a bit.

The problem of water ingress is unlikely to be directly related to being timber. The render in these systems is the rain screen so water is penetraing somewhere, most likely the upper window.

You need to get the builders back to find the source of the problem