borderfox100
New Member
I've been having some issues with water ingress through this wall. It's been acknowledged by the structural insurer that the one coat render was inadequate for an exposed site. Furthermore, full fill bonded bead insulation is being used in the 4" cavity. It's resulted in efflorescence on the surface of the internal wall inside the house.
As an aside, anyone like to comment on the horizontal nature of the cracking? People have mentioned to me that it must be wall tie failure but the build is only 11 years old - and stainless steel ties used. Others suggested settlement/subsidence (it's built on a raft foundation) but any engineers I've had on site have ruled this out. The insurers engineers reckon the plastering was done in 'lifts' i.e. sections by scaffolding height. Didn't sound logical to me (given some of those lines are very close together) but I asked a guy who worked on the development and he said walls were plastered in one hit - not in sections. These lines are present on the gable walls of EVERY house in the development.
Could it be that it was the blockwork that went up in sections and the mortar consistency differed with each section? Then again, how would this explain this being the pattern on every house in the development? The cracks seem to be at the very same points in each case (generally speaking).
Anyway, on to my next query. In order to determine the nature of the problem, I had to do a bit of invasive probing. Section removed from the outside wall and cavity insulation removed. The bonded bead full fill EPS insulation was wet to the touch. My engineer is of the belief that it's compromised. i.e. rather than it repelling water, it's conducting water - and carrying it across into to the inner leaf wall.
I also checked the floor screed inside - at the point where it adjoins the internal side of that wall. See the water mark up to 0.5m in from the edge? That led me to check the dpm/dpc internally - PIC. There's no sign of the damp proof membrane coming up and wrapping up around the edge of the floor insulation and the screed (between those elements and the block wall).
I then checked the cavity from the outside - removing the EPS bead right down to the bottom of the cavity. Here's what I found PIC. Just for clarity, what you're looking at in that photo is..
Top of photo = inner leaf blockwork wall
Bottom of photo = outer leaf blockwork wall
The Black item you see is the membrane, presumably the dpc rather than the dpm (?) but right above it is a major glob of mortar that almost bridges the cavity in it's entirety.
What I'm Trying to Achieve...
This is all being worked though with a structural insurer. They're not prepared to do the work themselves and are offering a cash settlement. Therefore, I have to get all my ducks in a row and make sure that EVERY defect is addressed as part of that settlement. They've priced their offer on the basis of re-rendering (3 coats plus 'webercote' finish) They will remove the cavity infill - clean off wall ties with high pressure lance and replace with certified EPS insulation material (or at least they have priced on that basis).
My other concern is the floor screed - and in tandem with that, what I found at the base of the cavity and the fact that there was no lining of membrane internally between the screed/insulation and the blockwork. No matter how well rendered, a certain amount of water will get through a blockwork wall. If it finds it's way down to that cavity base, is there not the potential for water to transfer through on TOP of the membrane - and be carried all the way through to the floor screed inside?
What works would be required in this instance to 'clean' the cavity floor and any idea of cost of same?
Lest anyone thinks this is overkill, I've spent 2 years arguing with insurers who were not prepared to pay out a single penny - despite the fact that the house inside and out is ruined with dampness. With that, I want to see to it that they live up to their obligations and cover the cost to allow me to reinstate to a position whereby this can never happen again.
As an aside, anyone like to comment on the horizontal nature of the cracking? People have mentioned to me that it must be wall tie failure but the build is only 11 years old - and stainless steel ties used. Others suggested settlement/subsidence (it's built on a raft foundation) but any engineers I've had on site have ruled this out. The insurers engineers reckon the plastering was done in 'lifts' i.e. sections by scaffolding height. Didn't sound logical to me (given some of those lines are very close together) but I asked a guy who worked on the development and he said walls were plastered in one hit - not in sections. These lines are present on the gable walls of EVERY house in the development.
Could it be that it was the blockwork that went up in sections and the mortar consistency differed with each section? Then again, how would this explain this being the pattern on every house in the development? The cracks seem to be at the very same points in each case (generally speaking).
Anyway, on to my next query. In order to determine the nature of the problem, I had to do a bit of invasive probing. Section removed from the outside wall and cavity insulation removed. The bonded bead full fill EPS insulation was wet to the touch. My engineer is of the belief that it's compromised. i.e. rather than it repelling water, it's conducting water - and carrying it across into to the inner leaf wall.
I also checked the floor screed inside - at the point where it adjoins the internal side of that wall. See the water mark up to 0.5m in from the edge? That led me to check the dpm/dpc internally - PIC. There's no sign of the damp proof membrane coming up and wrapping up around the edge of the floor insulation and the screed (between those elements and the block wall).
I then checked the cavity from the outside - removing the EPS bead right down to the bottom of the cavity. Here's what I found PIC. Just for clarity, what you're looking at in that photo is..
Top of photo = inner leaf blockwork wall
Bottom of photo = outer leaf blockwork wall
The Black item you see is the membrane, presumably the dpc rather than the dpm (?) but right above it is a major glob of mortar that almost bridges the cavity in it's entirety.
What I'm Trying to Achieve...
This is all being worked though with a structural insurer. They're not prepared to do the work themselves and are offering a cash settlement. Therefore, I have to get all my ducks in a row and make sure that EVERY defect is addressed as part of that settlement. They've priced their offer on the basis of re-rendering (3 coats plus 'webercote' finish) They will remove the cavity infill - clean off wall ties with high pressure lance and replace with certified EPS insulation material (or at least they have priced on that basis).
My other concern is the floor screed - and in tandem with that, what I found at the base of the cavity and the fact that there was no lining of membrane internally between the screed/insulation and the blockwork. No matter how well rendered, a certain amount of water will get through a blockwork wall. If it finds it's way down to that cavity base, is there not the potential for water to transfer through on TOP of the membrane - and be carried all the way through to the floor screed inside?
What works would be required in this instance to 'clean' the cavity floor and any idea of cost of same?
Lest anyone thinks this is overkill, I've spent 2 years arguing with insurers who were not prepared to pay out a single penny - despite the fact that the house inside and out is ruined with dampness. With that, I want to see to it that they live up to their obligations and cover the cost to allow me to reinstate to a position whereby this can never happen again.