Lowering patio level to below DMC

[Arthur]

The previous owners of my house have laid the patio paving above the DPC and its causing damp in the solid brick walls. I've dug a couple of trial pits next to the house and it seems there is a slate DPC about 75mm below the level of the top of the paving. The DPC itself is only one course above the footer foundations. I'm considering taking the whole patio up, digging down and relaying it at the same level as the top of the footer foundations (leaving a gap of ~250mm between the edge of the new patio and external walls filled with shingle). This would only be ~75mm below the DPC but I don't think I can go any lower as the foundations would then be partially exposed?
An alternative option would be to trim the existing paving stones back in order to dig a drainage trench around the outside of the house down to the level of the top of the footers. But I can't imagine this will look very good unless it were filled with shingle which would then risk bypassing the DPC. Furthermore, I'd be worried that the trench would just fill with water in heaving rain and end up coming into the subfloor through the airbricks (its all clay round here..).
If possible, I'd like to avoid the expense / effort of lowering the whole patio level, but I cant think of a good alternative. Any suggestions?
Thanks in advance

 

[a twig]

Search for “Zebcolm Trench” on this forum and it should give you what you are after

 

[Westholme]

My back garden is at top of footings level (albeit temporarily, for last nine years) and I don't have to worry about damp walls.

 

[Arthur]

Thanks for the responses. I had wondered about something like a zebcolm trench.
After doing a bit more investigating, it turns out theres an old concrete patio (possibly original) below the paving slabs. As the level of the concrete is 1 course below the DPC I'm considering removing all the pavers and the mortar bed on which they're sitting and leaving the concrete patio in place. As this would introduce a change in level thats not really ideal, I'm thinking about putting down some decking. Is the fact that the deck level is going to be above the DPC going to cause any issues? Presumably if theres a decent gap at the edge of the deck there won't be significant damp ingress into the brickwork above the DPC..

 

[Kearn]

Tomorrow the digger fun starts here!
By digging down to investigate around our perimeter, I created a moat. We’re basically built almost straight onto limestone bedrock, so water pools.
We have very high levels around our farmhouse, all getting lowered and sloped away from the building before eventually gravel / slab mix will go on as a permeable finish for new patio areas. Until I’m ready to finish, we’ll be able to see if the fall alone is adequate to keep water from pooling, or if we need to dig a trench away from the house to act as a small soak away.
Our plot is various heights, and the project always needed hard landscaping, so this was always on the cards here.

I’m wary of French drains and their interpretations, as there are always elements of failure - plus you need to send that water somewhere to drain/disperse. But when wholesale levels can’t be changed, I see the necessity and created one in our last house.

The raised decking, wouldn’t create a moisture issue - the concrete below may not remove the rainfall though so investigate first if it has the right gradient. And of course, where that water runs off to will be key as it won’t be soaking through the concrete.