700mm cast modular build

[david s]

I've started on a cast modular oven build and so far have laid an 800 mm high wall using 200mm blocks in front of another 800mm x 200mm existing wall with a cast slab sitting atop both, leaving a span of 920mm
In order to reduce slab volume, thickness and weight I used a 62mm thick cast steel reinforced slab with additional strengthening provided by two 4mm x 50mm gal angle. The slab has three weep holes cast into it near the centre, for under floor venting and two on the sides which will locate to communicate with the insulating layers. I believe this will work far better than a vent at the apex of the dome outer shell as well as looking a lot neater. Because moisture travels directly away from the heat source and the crown of the dome will be the hottest, pressure will force any moisture down to the base of the dome. This is also assisted by gravity. I'm interested to see how this will perform.

The first pic shows the slab from underneath, 2nd the slab from on top 3,4 &5 tiles and calsil.
The slab has now cured for10 days, the tiles glued in place and calcium silicate board cut and laid. I'm back on the job in two days to assemble the inner oven.

[david s]

I assembled the inner oven elements this morning just before the rain set in. Will now have to wait for it to cure and dry before proceeding to the insulation layers.

[david s]

I got a little more done this morning. Note the dome insulation vent holes in the supporting slab. I made some little cones in insect mesh to provide some space around the drain holes to provide an easier path for moisture escape. Also note, no chicken wire over the blanket layers.

[david s]

I installed the flue pipe (7" diameter) today and drilled some vent holes in its base. These should also allow moisture from the insulation space to exit into the flue pipe. After seating the base of the pipe with som castable refractory mixed with some perlite and vermiculite, I wrapped a layer of blanket around it, then covered that with some 10:1 vermicrete
I think this is a more elegant solution than having an exposed vent at the top of the dome.

Also attached is a drawing explaining my idea about the dome insulation vents in the supporting slab.