150mm

We're having a new patio installed and the builders are doing a great job. However, I'm concerned to see the new level is only 120 mm below the damp proof course in places. The new level also comes about an inch above the bottom of an air brick which doesn't look right and I suppose could...

To the left is the extension, on the right at 90deg to this is the original house wall. To the right of the patio door is next doors garden wall, running parallel with the extension. I have removed the existing concrete slab, which was less than 150mm below dcp level. We had no issues stepping...