Floor heat

Posted by Eric

I have just built an oven using the plans from Harrowsmith (Aug 04) It worked out pretty good but I did have some problems. I had a lot of cracking of the clay which I attribute to using too much water in the clay mixture. I think it shrunk too fast. I have been able to repair OK.
Questions:

1. The recipe was 2 parts clay, one part sand and a " handful of hay. I see other recipes that reverse this mix. What is right?

2. Too get more heat retention - can I put a cement mixture over top of the clay to add thickness and create a more weather proof structure?

3. My biggest problem is the floor. It does not heat up enough to brown the bottom of the Pizza even though the oven is fired at 700 degrees for 2 hrs. I did not get the dense firebricks for the floor. I used 2 inch stove bricks and they are rather porous. Is there any solution to salvage this mistake?

I think the Harrowsmith plans were OK but lacked detail and I did not know about the vast amount of info out there.