Your everyday house brick is fine for the base structure of the oven and you should find them very easy to come by. The bricks you actually use to form the oven are going to be much harder to get.
Firstly any professional will tell you to use "fire bricks" , these are impossible to get for free and cost @ $2.50+AUD each and you are going to need @ 100 of them !!
But my research has shown that MOST people don't use them, what they do use is "solids" these are bricks without the hole through them, I got REAL lucky and a house around the corner was being built from them so I got brand new ones never used for free !! , these solids are @ $1.10AUD at bunnings , they have a small indent in one side but no holes.
A guy in Brisbane kindly emailed me a reply to a few of my questions and also said that he has built 3 ovens so far and never used fire-bricks.
I was repeatly told in my research to use this type and NOT "wire cuts" these are solids that have no indent. I'm not sure why but I came across this advice alot so there must be some reason for it.
I saw heaps of ovens being built with bricks that had holes through them but they were all red in colour so they must be clay based, my belief is "solids" is the way to go on the cheap.
one reason they use fire bricks is they have a VERY straight edge and you can buy them angled so you can actually use no mortar (more on mortar later) .
Many people used fire bricks for the base as well but I will be using clay pavers like many others, i'll also be using Hebel http://www.hebelaustralia.com.au/ as an insulating layer under the pavers but ontop of the top slab of concrete. Once again I got the Hebel for free from a building site, hebel can be cut with a hand saw so its easy to work with.
