Our oven bases are designed with 8” x 8” x 16” block that is 5 layers in height. This common dimension allows any oven user (of average height) the ability to insert, rotate and remove food at a comfortable level. BUT, if the end user is below 5’ 8”, we would recommend building your oven base 4 rows in height. This will bring the oven down to a more comfortable level.
Also, the height of the 8” x 8” x 16” blocks has zero effect on the performance of the oven. If you want to raise your oven by 10 layers (10 blocks in height) so you can use it on an elevated patio or deck, that would be okay. Just be sure to use plenty of rebar and fill every core with rebar with cement. If you are going above 5’ in height, have your oven base designed (or signed-off) by a structural engineer.