We had a conservatory removed at the back of our house and are planning on replacing it with a patio. However, the concrete slab that was under the conservatory is only about 75mm below the DPC, so by the time we put the paving on it and factor in a fall away from the house, the ground level will end up at best level with the DPC. I know building regs require 150mm below DPC etc, and I've read lots of posts about similar situations but I have several questions if you don't mind.
1. We are planning on installing an ACO drain along the wall of the house. Does it matter if the top of the ACO is only a few mm below the DPC? I'm sure in an ideal world it should be 150mm below. Is there any benefit to installing it lower and then filling in with gravel on top so that it is level with the paving?
2. If we install the ACO, can the paving be higher that both the top of the ACO and the DPC? Need to make sure we have enough height for the fall away from house
3. Is there a machine that could lower the height of the concrete slab by perhaps 20mm in places? It is very uneven and bumpy. Something like one of these? https://www.hss.com/hire/p/htc-gl450-grinder, https://www.hss.com/hire/p/surface-scaler-starwheelelec
Thanks in advance
