I'm installing the drains below a concrete slab and have just realised I don't know how far it should be away from the wall. Any guidance would be a great help as I don't have an existing one to measure.

My advice would be to wall hang toilets and wash basins. No dirt traps around the base and much easier to mop floor.

Posted By: Chris P BaconMy advice would be to wall hang toilets and wash basins. No dirt traps around the base and much easier to mop floor.

Hmm, my wife wanted the same for the same reason. But the frames make wall-hung significantly more expensive, and in our case we can't (well, don't want to) hang from externall walls. So now we're going with back-to-the-wall pans. They're at least as smooth and less total surface area, if you add up the pan and exposed floor.

My soil pipes are very close to the wall, which is a pain. Especially if you want to add airtightness sealing. We'll have to add offsets to get them far enough away from the wall to pass through the first floor joists.