Just completed my oven and have not finished curing fires but it seems to hold heat for a long time. It was a challenge to find materials here but it can be done...glad to help anyone wanting to build by providing details.. I used the free plans and had to adjust some things. #1 is soak brick!! The sun is just too hot and sucks water out. So many things are made from concrete in this country and I see lots of repaired cracks in many buildings, etc. I had to slow the drying time by soaking longer and covering with wet cloths, plastic; both on the bricks & stucco covering. Still have some very minor cracks in my stucco but have coated with a sealer and crossing fingers.