Patio still too high?

[Mutzgoatz]

We moved into our mid Victorian terrace in Dec 2018. Soon noticed rising / penetrating damp in the dining room and sliding doors. At this time, the external ground was 10cm higher than pictured, in line with internal floor level, covering the airbricks under the sliding doors, and made up of fake grass laid over sandy compact soil! Shocking arrangement that surveyor didn't comment on!

I'm December 2019, we got the ground dug out, a patio laid and a French drain gravel over hardcore border around the perimeter and airbricks reinstated. There's also and eco drain that water can drain into in the middle.

Patio is only about 5-10cm below interval floor level, probably less in places.

Unfortunately, this is the lowest it could go, as the soil pipe return running underneath, leading to the sewer was quite high.

We found a modern DPC on the latter end of kitchen extension end (about 5cm above gravel border). Not ideal, but least it's above. No evidence of damp ingress that end anyway.

But underneath sliding doors and running along the original kitchen side wall, we couldn't see any DPC. The contractors assured us that despite not being the recommended 15cm below internal floor level, the gravel and hard-core border and fall away from house would make it ok.

The bricks in line with patio height (below where the old black bitumen paint is) have remained pretty damp since. Internally the damp still slowly progresses.

Recently I dug up some of the gravel border, as pictured, and discovered an old slate DPC. But it's so low, like 20cm below internal wooden floor level. And still probably 10cm below patio level (I.e. The gravel border abuts it and goes well over it by 10cm. Can't believe how much lower it us than the newer DPC at the end of the kitchen.

Does anyone gave any advice in the circumstances? What I fear is that we've been screwed over by patio contractors and it all needs redoing, otherwise it'll be an issue when we sell. But on the other hand it seems they worked within the limits present - the high soil pipe return and old, low slate DPC.

While not ideal, is the gravel border and maybe a DPC injection in line with internal floor level say (plus replastering) a reasonable solution in the circumstances?

Thanks a lot.

[Tony McC]

No image, so difficult to comment, but once again it's that dreaded phrase, and reliable indicator of a clown, "French Drain".

Post an image or two, or send them to me to upload, and we have a better chance of being able to suggest a remedial strategy.