mattchan

Whats the campings? Is drywall adhesive foam bad stuff?

Just for reference the cross section detail above was a quick drawing i did to try and explain the situation I'm in rather than something the builders / architect came up with before / whilst working. Below is a zoomed out view of the inspection hole i showed in the first post. You can see the screed and DPM which is lapped up past the DPC shown in blue in my diagram above. Other pics for reference so you dont need to scroll...

The neighbours haven't extended, the room the other side of the wall used to be their integral garage. From what I can find out from BCO records and the architect who did my plans and theirs, their leaf of the wall has been their since the houses were built and the only addition when the garage conversion was done was to build their floor level up. I don't know the answer to if that cavity is a result of bad workmanship. I assume it is and they just werent too bothered in the 80s when it was built. The wall is exactly in line with the party wall between us for the rest of the house. Foundations were exposed and inspected by BCO when the wall butting up to theirs was built by the builder. We have a party wall agreement in place. As mentioned in my post just above the slab etc is already in and was completed by some long gone builders. So is that effectively a 20mm waterproof render with a polymer waterproofing slurry over then tape the floor DPM to this? Then go over this with an insulated plasterboard? As a point of interest why don't the injectable DPC creams work?

That cavity tray has already been installed. The builders who did that part and laid the floor etc are long gone, sadly they didn't identify the issue above whilst doing the work.

I have some cables that have been attached to a brick wall with upvc capping. The original plan was to float and set the wall, now it has to be covered in 37.5mm thick insulated plasterboard that will be attached with adhesive foam. Thermally the worst case is the capping in direct contact with the foam. What reference method for cable derating should be used in this construction?

Ah, so in my diagram above move the green proposed injected DPC up by 6 courses and the pink DPM extension a course above that? Thats my next concern really.... the extension sits inline with the existing house. The construction in the other rooms that are on to the party wall is just sand and cement float and set over the brick. The BCO just wants 25mm horizontal batten applied to the wall with 25mm celotex between the battens then boarded over. I just wanted to sort out the DPM etc first.

@tonyshouse sorry to nudge you on this but I wonder if you would mind clarifying exactly how far up the tanking should go?

As in tank the entire wall right up to roof level? Would the DPC then just be there to stop the damp getting to the roof structure?

I have had an extension built that has turned a piece of party wall that used to be outside into the inside wall of my kitchen. There seems to be a slightly strange construction to the wall which results in the DPC on my side being bridged by some flinty infill on the neighbours side. I was wondering if i should inject a DPC on the green line in the diagram as shown below and then run the DPM up the wall past this to avoid the bridge? Here is a cross section from an exploratory hole cut in the wall. Green is neighbours inner skin and 70mm cavity. Red is the slab butted to the outer wall with the thin DPM directly onto the flint.