On the second day, Sunday (after church, of course!), we built the walls that will form the support for the oven. This is an area that is used for wood storage as well. Some ovens are built with an ash slot so the ashes can be cleaned out of the oven without bringing them to the front of the oven. We decided against an ash slot and will use a metal can to collect them and them move them away from the oven. We have a small backyard and will be looking at the oven a lot. We didn't want to look at a trash can marring our pretty oven. We used ordinary 8" x 8" x 16" concrete blocks (with a few 8"x8"x8.") and mortar. Larry used the level throughout the building process to keep us level. We used leftover concrete (rubble) to core-fill the blocks. Two pieces of angle iron hold up the blocks above the wood storage opening. We did 2 thing differently then described by Alan Scott . We used one less row of block (His plans called for one row of 4" high blocks to make a 38" working height) We used 4 rounds of 8" block, figuring on making the final working height of the hearth around 36". That's the usual height for kitchen counters and it's a good height for gazing at a fire if we're sitting in our backyard.