Patio level above DPC

[Arthur Lewis]

There is a bit of damp in the external solid walls of my house where the patio has been built up above the level of the DPC, bridging it. I believe it may have also covered air bricks so the underfloor void is unventilated. I've sketched the current arrangement. I'm considering what would be the best way of getting this sorted:
- Option 1 would be to reduce the whole patio level down to the level of the top of the footers (probably how it was intended when the house was built). This is going to be quite alot of work and will create a step down to the patio from the house and also from the lawn which isn't ideal.
- Option 2 would be to create a trench around the external wall down to ~150mm below the DPC and fill with shingle and bigger stones above the DPC. This would be much easier the airbricks would still be covered.
Are there any better options / alternative ways of getting ventilation to the underlfoor void?

Many thanks in advance

 

[Burnerman]

I had exactly this problem, and I went for your option 2.....but I left the trench open, covering the top with some galavanised steel mesh to keep the leaves out etc. Damp gone, and there is now a gale below the floor!
John