[SteveInNZ]

I want to put a pier on to an existing concrete surface. The surface isn't particularly smooth and it has a 1 degree slope in two directions. I was thinking of having a base plate 500x500 and using 12 sleeve bolts to attach it to the concrete.

Since there could be 10mm gap between the plate and the concrete, plus say 5mm for the rough aggregate surface, what would be the best way to level the surface to bolt the pier on to ? Is that the way to do it, or should I have spacing washers under each bolt or something ? I'm not sure if leveling compound is intended to level that much.

Any suggestions appreciated.

Steve.