Thermal expansion in floor/vent landing design

[jschwappach]

Hi all,

I'd first like to express my admiration at the creativity and engineering capability of the folks on this forum. You have truly inspired me to think that I might be able to build an oven myself, despite my lack of masonry skills. So thanks for that! -- (wife not so thankful, however, since all I've been able to talk about for the last two months is pizza ovens!)

I'm in the design stage for a 42" Pompeii.

I'd like to build the dome around the floor to maximize heat retention. I've noticed that a lot of the ovens on the forum that use this design DO put in a gap between the floor and the dome and between vent transition and the entry arch to allow for thermal expansion.

However, once into the vent landing, it looks like most people do not leave a gap for expansion between the vent landing and the vent structure/decorative arch, and between the firebricks and the oven landing.

I'd appreciate thoughts on whether a gap between all floor bricks and all vertical structures would be worthwhile. In my newbie way of thinking, there's a lot of heat in one of those ovens and the more expansion joints the better. Even if the vent landing floor isn't getting too hot, is it moving around as a result of the expansion of the cooking surface bricks?

Any chance the lack of such expansion joints might be causing some of the issues with cracks in the arch and other structures?

Thanks,
Jim

[RCLake]

Re: Thermal expansion in floor/vent landing design

Hi all,

So thanks for that! -- (wife not so thankful, however, since all I've been able to talk about for the last two months is pizza ovens!)

Thanks,
Jim

It's catching, soon they will be on board as well!

[Acoma]

Re: Thermal expansion in floor/vent landing design

Jim, brick expansion based on saturated heat is something like .21 max. This is why those that are building the dome around the floor bricks are leaving 1/8 to 1/4 gap. As for the entry area, no gap occurs with wall bricks to floor because the heat is much reduced, although it still exist. The heat likely does not expand the bricks enough for such concern. I hope this answers your question.

[gjbingham]

Re: Thermal expansion in floor/vent landing design

I removed my vermiculte/concrete layer on the outside half of my landing area. I developed 1/8th inch gaps between some of the bricks from the heat expansion. I think it has something to do with the differences in the insulating abilities of vermicrete v. concrete. It makes perfect sense to me (now) that the entryway is subject to different expansion/contraction than the dome. My soldier course was on top of the floor, if that makes a difference.

The .21 expansion might be significant. I'm not sure if this number is a percentage. I'm pretty positive that different manufactures of bricks have different numbers too.

[Acoma]

Re: Thermal expansion in floor/vent landing design

I have a quater gap for my dome, none for the arch. My entire wall system is off the floor bricks.