The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

metal oven roof condensation problems

barnowlbakery's picture

metal oven roof condensation problems

Hey guys,
First time poster but boy have i pored over these forums during the last few months as I built an Alan Scott style WFO with a 3'x4' hearth for a small bakery my wife and I are building on Lopez Isl. Soon I'll put up a post with lots of pics and some things i learned along the way, but first a question!

I boxed the whole thing in with metal studs, sheathed with concrete board. Insulation is ~4" of perlite covered with ~18" of mineral wool insulation, essentially filling up the box. I roofed the whole thing with corrugated roofing screwed directly to the steel studs. There's one large vent just under the eaves, but no ridge vent.

The oven cured for ~5 weeks, with lots of small fires, and eventually a few big ones before the insulation went in.

Now the problem!

I've got lots of moisture in the oven box and from the looks of it it's condensation on the metal roofing. Enough to soak down through the insulation on the side of the oven, through the insulating slab and out into the chamber below the oven. At first I just thought it might be a leaky screw in the roofing but I think there's too much water for that.

Any other oven builder ever have experienced with condensation? It makes sense that condensation would happen as the warm oven air hit the cold metal roofing, but where's the moisture coming from? in through the vent? out of the concrete?

Any thoughts would be appreciated!

I have a few pictures up on the web for on our kickstarter project that we used to originally fund the oven.

check them out here:


Faith in Virginia's picture
Faith in Virginia

Sounds like a venting issue.  One large vent in the eave could be one of your problems.  The eave vents should run the full length of the eaves.  Ridge vent is a must.  For metal roofing they make a ridge vent that fits under the cap (looks like a scotch bright pad).  If the outside temperature is cool and the area over the oven is warm you will get condensation.  Think of a cold glass of tea on a hot summer day , and the condensation builds on the warm side.  Proper venting will keep both sides of the metal roofing at a similar temperature and condensation won’t build. 

Take what you described and high humidity, you could generate a lot of water.