I'm renovating a Victorian terraced house at the moment. I've ripped out the kitchen units and stripped the tiles off the walls to find the plaster behind is saturated.
Its had a DPC injected at some point (regular holes drilled in the bottom course of bricks) but has incorrectly been replastered (for a damp wall) with a gypsum based backing plaster which was also down to the ground, thus bridging the DPC. What I also discovered is the outrigger which contains the kitchen and has 3 external walls is built from a single skin of brick. The dampness extends to the ceiling so appears to be penetrating as well as rising, not a surprise given the single skin.
I'm considering how best to remedy this and have come up with the following options:
1) Inject new DPC and replaster with a sand/cement render + waterproof additive.
This would be cheapest and quickest but I don't know how long waterproof additives remain effective and it would offer crap insulation to a room with high condensation levels.
2) Build a second skin inside from lightweight breeze blocks with plasterboard over.
Still cheap, would solve both damp issues and improve the insulation a bit, but I can't afford to lose enough space to leave a big cavity with insulation, just a small cavity (25mm) to stop damp bridging.
3) Build an inner skin from timber studwork with Kingspan between the studs, cover with ply or OSB sheets and plasterboard.
This would solve the damp, greatly improve insulation and the ply sheets will make fixing units to the walls easy but will be the most expensive and probably time consuming.
4) Glue Kingspan (25 or 50mm) to the wall with silicone (just to hold it) then put ply sheets over it fixed to the wall through the Kingspan with window frame fixings like these
http://www.toolstation.com/shop/Screws+Fixings/Frame+Fixings/Hammer+Fixing+...
and plasterboard over that.
This would improve the insulation, be quicker than 2 and 3 and cheaper than 3 but is a bit of a wild card. I've never heard of it done and although the Kingspan should stop damp reaching the ply, water might build up behind it.
Bearing in mind this last point, should I put some weep vents in the outer wall if I go for 2 or 3.
Any comments on the above, or alternatives welcome. Thanks.