gaps between floor and walls

[Infornata]

There are some pretty major gaps between the floor of our modular casa2g90 oven and the dome walls. We've made them pretty even on all sides and the gaps probably range from 1/2 an inch to 1/4 inch all the way around. In the pictures I've seen of these ovens, there are no gaps at all. Is this a problem? do we have a defective oven? Are we supposed to fill this with mortar?

[mrchipster]

Originally Posted by Infornata

There are some pretty major gaps between the floor of our modular casa2g90 oven and the dome walls. We've made them pretty even on all sides and the gaps probably range from 1/2 an inch to 1/4 inch all the way around. In the pictures I've seen of these ovens, there are no gaps at all. Is this a problem? do we have a defective oven? Are we supposed to fill this with mortar?

There are always gaps, my brick oven has a 1/4 inch gap designed in to allow for the variable expansion and contraction of the floor vs the dome. The gap was controlled by unserting corrigated cardboard arround the floor before building the dome. This area will fill with ash from the fires over time and you can even sweep ash in the gaps on purpose at the end of each fire. Less to remove.

Of course in my case the cardboard will need to burn out first but that is just addition ash.

Chip

[HeidiL2011]

Hello Infornata,

The gaps are normal to allow for thermal expansion of the floor tiles, over time the gaps will fill with ash and you won't be able to see them.

If you have any other question you can always contact me at 1-800-407-5119 ext 14

Thanks,
Heidi
Forno Bravo

[Amac]

Hi Heidi
New here and just starting my own build. It seems to me that if such an expansion gap is needed then it would not b a good idea to build the dome on top of the floor but rather around the floor as what would happen to a dome mortared to a floor if the floor is expanding under heat?
Anybody got thoughts on this
Aidan

[brickie in oz]

There are lots of ovens with the dome on top of the floor with no problems.
I think the base and dome would expand at the same rate, if it was different it would only be marginal.

[david s]

Particularly when firing the oven for the first few times to drive off the moisture (I hesitate to call this "curing") you will find that the base of the dome will be way cooler than the top and middle of the dome. This will be indicated by a persistent ring of black soot at the base of the dome. This also means that the expansion is less in that part, so if the floor has already expanded there is some stress created. A floor with unmortared bricks is better in this regard because the brick gaps can take up some of the uneven expansion. The gap between the floor and the dome does the same trick. Once the oven is properly dry it will heat up much more evenly and not create such extreme differences in expansion.
Excuse the long winded explanation, but it is easy to mis- understand what is going on here.
This could also be all bullshit, but that's the way I see it.

[brickie in oz]

Originally Posted by david s

(I hesitate to call this "curing")

Maybe "seasoning" would be a better term, they season timber to drive out the moisture?

[brickie in oz]

Back to expansions.

Do you think the difference in expansion rates would harm the oven?
My dome is on the hearth and the only so called fault I can see is that the hearth bricks have slightly larger gaps between them than were there to start with.
Im talking <1mm gaps from zero gaps to start with.

[david s]

Why aren't you at work- you lazy bastard. (it's 37C in the shade here now, i'm in side with the aircon)
I believe it is the rapid heat rise which results in uneven expansion which is the culprit and that which damages the refractory. We are taking these ovens from ambient to 300C in one hour, that equates to about six times the recommended rate of increase for driving out the moisture. This would then take you 6 hours to get your oven up to 300 C. No one is going to bother taking this long to fire their ovens, but it is vital if you want to prevent damage when "curing" I prefer to simply call it "driving out the moisture" because that describes what it does.
Now get back to work!

[brickie in oz]

Ive had no work for months........(insert quivering lip smiley here) things have slowed right down here in Vic, contrary to what the government leads you to believe.
All Ive had had for ages is dribs and drabs.

I was offered a 2 story house the other day but its a bit hard to do on your own.