I am about to install the floor in the extension I am building on my house. Total area is approx 20 sq m and the floor is to go onto the concrete raft foundation slab. It will consist of dpm with 75mm celotex and 75mm fibre screed on top. My question is can I use concrete instead of screed? This is simply because it is easier (and considerably cheaper) for me to mix and install concrete myself using my own mixer. I would reinforce the concrete with chicken wire or similar welded mesh. The new kitchen floor would then be tiled. Any advice would be greatly appreciated, thanks.