I have read quite a few posts here and looked at other sites also. My question lies in the bricks, I have the chance to get over 1000 red bricks for free as long as I load and carry. The possible problem is these bricks have 3 holes in them and I am assuming that they will not be sufficent for use as a main component of the oven. I know I can use them to finish the oven but not anywhere heat might transfer. Am I correct?