Day 2 - Lintel and Cross Supports

Today we brought the 6x8 concrete lintel over and laid it in place. I also mixed up some more mortar and filled the last course of block solid. To prevent it from going all the way down to the first course, we stuffed newspaper down in the third course... it worked beautifully. Yesterday we had some leftover mortar, so we filled all 4 corners solid as well. I don't think this would be absolutely necessary for this size oven, but since we had leftovers, we used it in combination with scrap pieces of block. However, with the heavy lintel, we did want to make sure to fill the front two corners.

As far as the cross supports, you will not find this in The Bread Builders at all, and I am probably overbuilding the oven. The reason I am doing it is two fold. First of all, I am planning on pouring the hearth slab using portland concrete rather than refractory concrete. When portland concrete is heated to 750 degrees F it loses half its strength which does not return when it is cooled. Knowing that the hearth will be getting very hot (although unlikely to get to 750), it will therefore be getting weaker. So I am just taking precaution (and I have extra block laying around... if I had to buy the block, I probably would not put this in). The second reason is that this was one of Alan Scott's later improvements to his commercial ovens. These two pictures below are of one of the first ovens he built, and notice how the hearth slab has sagged over the years. This reinforcement would hopefully prevent such sagging.

It is hard to notice, but there is a 1-2 inch sag in the middle.

You can see the sag a little better from below.

I also did not bother mortaring in these reinforcing block. However, I may do it for two reasons: First, to keep wasps from finding holes and making a giant hive in the back of the oven. The second reason is I need to raise it 1.5 inches for the vermiculite slab that will be sitting on it, so the mortar will be just enough to do that. Ok... here is what I did today...

The lintel was actually 1 inch short, but that is no big deal, it will just be covered up anyways. 

I left a space there in the lower right for a piece of rebar which will support the slab.
When I figure out exactly where it will go I will put more mortar in there, but still leave
some wiggle room so the expanding rebar won't crack the block.