Hopefully the reason

[roobqn]

I am hoping this is what is happening, but thought I would double check.
I finally got our Scott Style oven bricked up and the roof on. Prior to the roof going on, we placed 6 inches insulation over our 4 inches refractoy insulation. Today we fired up the oven and were really happy that the oven ramped up to 350F within a half an hour, however things slowed and it took another hour and a half to get to 600F. As we were only doing brussel sprouts and bacon wrapped scallops, this was fine.
When I went to put the door on for the evening, I noticed what at first I though was smoke coming out from under the new roof eve. However upon further inspection, it was steam (no smell of wood burning). Reached inside the brick enclosure under the eve and it was fairly warm and humid in there. This also surprised me as before we enclosed it we could touch the outer surface while firing up without it being hot or even warm. I still have the coals raked over the floor driving heat into the slab below the floor.
We have only fired the oven 3-4 times before buttoning up, so I am wondering if I am still driving moisture out of the oven, warming up the interior of the brick enclosure and since it is around 50 degrees outside causing steam. The oven itself with refractory insulation has been completed and open to the air since the end of June.
Thanks for any help you might be able to offer.

[brickie in oz]

There is a thread on curing ovens on the forum somewhere, getting to 350 on your first firing will crack your oven.

It should be cured slowly over weeks to drive out the moisture.

[roobqn]

Sorry for the confusion, we had done series of curing fires back in June/July. We used refractory cement as well as refractory insulation and the curing instructions for this refractory cement is to heat hot and heavy from the git go.
I wasn't really comfortable with that, so did the slow "cures" before the really big fires.

[brickie in oz]

Phew....... thank goodness for that.

If you dont fire often and rain/moisture gets into your oven it still takes ages to get to full heat.

I have that problem here (Melbourne AU) so I usually fire for hours before a party or the day before to drive the moisture out so I can attain maximum heat.

[dmun]

Also, Barrel vault ovens have much more mass, hence much more ability to absorb moisture. It should get a little better with every firing.

[Tscarborough]

Barrel vaults CAN have more mass, but they can also have less. My dome is thinner than an FB oven by about 1/2".