sand under firebricks?

[Poetryart]

yippee! It did, it did!
The perlite/portland cement has been drying for almost 24 hours. There's still a little "crumbly" surface on top, except where I dumped the slush from the bottom of the wheelbarrow - seriously wet stuff - it's now the firmest. Should I go back and put a layer of soupy portland on top to seal it? I do plan to put some tiles on for finish. This weekend we'll put the FB blanket on, and the layer of portland/perlite on top of that. We still need to decide exactly how to do the flue. We'll stucco for the dome finish.
Don't laugh at the shape of my dome, btw, I know it looks a bit like a big zit...but that will get covered up. I hope....

[Poetryart]

another view.
i hope.

[cobblerdave]

Gudday
Thanks for the the pics... ovens looking good!!!....your on the home stretch now...

Regards Dave

[cobblerdave]

Gudday
Just hoping for a few more pics on your progress to date

Regards Dave

[big dumb & stupid]

Just to confuse you have you thought of using broken glass under your hearth, loves heat and if broken to very small pieces it will tick all the boxes.
Sri Lanken bakers use this method and they have some very hot/even ovens

[david s]

There has been plenty of discussion on using broken glass as an insulator if you do a thread search. It was used extensively prior to modern insulating materials. The air spaces created between the bits of broken glass are what gives you the insulation value. Curved glass is better than flat pieces because they create more air spaces.

[Dagored154]

I am using 3 1/2" soapstone bricks under the fire brick instead of the FB Board. can I just use sand underneath them and not mix it with fire clay? any thoughts.

[mrchipster]

Do you mean soapstone or insulating fire brick? Soapstone is a great conductor of heat and not an insulator, FB Board is an insulator and your plan to use soapstone will be a serious mistake. You may not even be able to get your oven up to temp due to the thermal loss.

Insulating firebrick may be a useful choice but I think it would be quite expensive when compared to FB or some other ceramic insulating board.

Just my two cents.

Chip

[Dagored154]

an old acquaintance of mine has built dozen of home and commercial ovens. and has used them as well. He suggested the soapstone bricks underneath instead of the FB board. He sure seemed to know what he was talking about. I hear what you are saying so I will speak to him when he returns from Canada.

[mrchipster]

You will go through lots of wood with no insulation under the floor.

Just because your friend builds them this way does not mean it is best practice, please research heat loss through the floor or insulation techniques on this site. I have 2.5 inches of vermicrete and 2 inches of FB board under my floor and can cook all week on one firing of the oven, pizza first night and ribs on day 6. With bread, roasts and casseroles in between.

Chip