I'm renovating my 1900's house, and have a tiled floor which is laid onto lime mortar and then dirt which is damp. I've made the decision to dig out and replace this floor. It's been suggested to me by a friend in the trade that it would be suitable to dig out and level the dirt, blind with sand, add a DPM, 100mm of insulation and then add a chipboard floor without any screed or concrete slab. I like the idea of this, as there's a considerable time saving involved, but doing some research i can't find any guidance which doesn't involve putting in any concrete slab or screed anywhere. Any advice greatly appreciated.