Orientation of bricks for dome floor

[jonv]

Hi,

I am planning my build and thinking of providing a thicker floor than the usual 2.5" of brick...

What is better - to lay the bricks on their side, so making the floor of more narrow strips, or to lay them flat in two layers? If the latter, what would folks recommend putting between the layers, if anything...

I would prefer not to mortar the top layer, so that a brick could be replaced - at least, in theory if not in practice

Any alternative suggestions would be welcome too

thanks,

JV

[stonecutter]

Re: Orientation of bricks for dome floor

If you want that much mass on the floor.....

I would lay the hearth brick on their side in a 45* herringbone pattern. If you choose to layer them, then you can easily level the top course by screeding a thin layer of sand/fire clay over the base brick, same as over an insulation layer.

[jonv]

Re: Orientation of bricks for dome floor

OK - thanks

I am leaning towards the thicker floor for bread purposes... rightly or wrongly...

[stonecutter]

Re: Orientation of bricks for dome floor

It's right if that's what you want.

[Tscarborough]

Re: Orientation of bricks for dome floor

Better not to layer them, the gap between works as a thermal break. Better not to have a 4.5" floor either unless you plan on multiple batches of bread. You would do better having more insulation than more mass.

[dakzaag]

Re: Orientation of bricks for dome floor

Better not to layer them, the gap between works as a thermal break. Better not to have a 4.5" floor either unless you plan on multiple batches of bread. You would do better having more insulation than more mass.

I know of some professional bakers who are building the floor 9" deep. (setting the firebrick on end.) Seems outragously deep, but if the oven never cools, you have a huge mass to bake with.

[Tscarborough]

Re: Orientation of bricks for dome floor

Absolutely for commercial use. But even for a weekly baker, 4.5" is more than needed. You have to heat soak the mass for post-fire cooking, and it is hard enough to do so with 2.5". If you do not mind burning a 5 or 8 hour fire, go for the 4.5", if you want to have a 2-3 hour fire, go 2.5".

[Wiley]

Re: Orientation of bricks for dome floor

Here's a short bit on hearth construction with regard to speed of heating, recovery etc.:

Wood Stone Points of Difference for Comparing Ovens

If I were interested in commercial baking I would consider a single piece hearth as the hearth is the hardest part of the WFO to heat. Orienting the bricks on end creates the most lateral area for brick to brick transfer of heat with the smallest area of each brick in direct contact/exposure to the heat source. This would seem to be very inefficient.

Hope this helps,
Wiley

[david s]

Re: Orientation of bricks for dome floor

A one piece floor has problems with uneven heating and therefore uneven expansion leading to cracking. This also is a problem with a one piece cast dome. The remedy is either to reduce the size of the castings to create multiple sections or strengthening with ss needle reinforcement. I chose to do both and my floor is a two piece casting with a tongue and groove join down the middle.

[stonecutter]

Re: Orientation of bricks for dome floor

Tom, I doubt a thin screed of clay and sand would act like a thermal break.

[Tscarborough]

Re: Orientation of bricks for dome floor

So did I when I built mine, layering with refractory cement the elements of my Gustavino arch, but I can tell from it's performance that the layers have delaminated and act as a thermal break.

[jonv]

Re: Orientation of bricks for dome floor

Hmmm, a lot to think about there... I certainly don't want to fire it for hours before I can cook; on the other hand want enough heat to be able to bake a few batches of bread.