Used them to install about 1000 sq ft of slate and tile and although they were good to work with in most regards, I recommend not using them for installing slate unless you want a very«rustic» look with much lippage and unevenness. They were good about coming to «fix» the issues with a hammer and chisel but the floor definitely is rustic — nothing like the other 3 slate floors I have done in the past. Also, watch your quote if tiling over a cement basement floor, they do not include leveling of uneven poured cement flooring in their bid and had I not stopped them, they would have laid the large tile without leveling and I’m sure the outcome would have been a disappointment.