Day 3 - Prepare for Pouring

Still doesn't look like an oven, but we are making progress. So I did decide to cement in the cross supporting block, and then put an additional 4-inch block to bring it up to the level I want to pour the insulating vermiculite concrete. Like all the rest of the pictures you will see in this post... I am using what I have laying around. You might find a much better way to accomplish the same task. My main goal was to get the top of the block to a height 4 inches from the top. This will leave room for a 2-inch vermiculite concrete slab, and half of a 3.5-inch hearth slab (you will see more of this later).

Hard to see from this angle, but it does not quite touch the back wall,
it is about 2 inches short

The next step was to build a platform to pour the concrete on top of. I built two platforms, one in the back and one in the front. Now my plans evolved to the point where once the concrete is poured, I am going to leave the plywood there forever stuck to the underside of the poured slab. For the back section, I have no choice in this matter... once the slab is poured, there is no getting back there to retrieve the lumber. As for the front part, it was just easier in my case to use the supporting block as a lip, and then three additional supports on the other end (see pictures). This made it incredibly secure without one nail or screw. If you look at the picture below, I had to rig up a method where I will be able to knock out a section of wood or block (once the slab is poured), so that they do not have to stay there forever as well. Again, using what I had, I was able to make something very structurally sound.

A 2x4 going across the three supporting legs greatly
increases its strength for the plywood going on top.

The plywood is now resting very securely.

 Today I bought 8 pieces of rebar: four 44-inch and four 48-inch of 5/8-inch rebar. The rebar should be at least 3 inches from the edge of the hearth slab, and no two rebars should be less than a foot apart. So make sure to do your math, measure a couple times, and then you can start making the grooves. I used a borrowed saw which has a diamond blade on it for cutting through concrete. Wear plenty of face protection... portland cement is a nasty thing to be breathing in, and these saws are loud!

Making grooves for the rebar

It should have a little "wiggle room" for when it expands a little.

Now this is completely my own thing here. I don't want the board to start
sagging someday. So I put nails through to secure it to the concrete.
Remember, I am leaving them in there forever after taking the
supporting legs out from underneath.

Put the wire mesh in for the vermiculite concrete layer. I snipped a bunch of wires
to better secure it to the hearth slab which will be poured on top of it.

There is more to come tomorrow or the next day (whenever the rain stops). We will be pouring our vermiculite concrete, make a frame for the hearth slab, and then pouring that as well.