Damp proof course and patio

kjs31

Thanks all. Here is what the surveyor wrote in his report 

Damp proof courses (DPCs) were visible above ground level; they should be at least two courses high above ground level (150mm, the minimum required height) but appear to be reduced along the rear external walls where the pavings have been laid, reducing the effective height of the DPC.

The perimeter low level brickwork, relative to external ground levels, is partially weathered and local apparent saturation and spalling of the bricks are evident. It is possible that local elevated of moisture in the masonry could increase as splashing rainwater saturates the brickwork above the ground, allowing moisture to potentially penetrate through the wall and establish itself as ‘damp’, with the potential for premature rot to occur to timbers in contact with the walls and also blistering of internal plaster and redecoration finishes.

Ideally, where the effective height of the DPC is less than 150mm (6”) above ground level, it should be effectively raised by removing materials abutting the wall to create a channel, in order to restrict splashing rainwater saturating the brickwork at an elevated level. Often, clay land drainage pipes are laid within the channel, connected either to the drains or to a new soakaway, and mineral chippings laid over, commonly referred to as a ‘French drain’. Some owners prefer to install linear channel drainage to limit water absorption, which we believe is a more robust approach.

So I guess the 6k is proposing the full Monty approach. It was raining when the survey was done and also on one of the occasions that I viewed. I didn’t see any evidence of water pooling at the back of the patio and it’s been pretty wet here. 

I think I’ll adopt a wait and see approach as in theory we should complete in May when the better weather arrives. I think it’ll be a non issue (for me) until next winter. The patio has been down a while and obviously hasn’t concerned the current owners (who in general appear to have kept on top of maintenance issues).  The wall in question is south facing and in SE England if it makes a difference.