Good question -
The BEST way to keep moisture out of any oven (not just our brand) is to…
Use a door. This will prevent rain / moisture from entering the oven.
Close the damper on the chimney when not in use. This is more to block moisture vs. keeping rain out. A damper will not keep rain out.
If you do have moisture in the oven or if the firebrick cook surface feels damp, you want to dry it out before you start a large fire. A large fire will turn the moisture into steam and as you know - steam can EASILY crack brick, concrete, etc…
True story - I was having a neighborhood pizza party on a random Saturday at my parents house (on one of the first pizza ovens we ever built). The night before, my father “cleaned” the oven by washing it - inside and out. Now, his version of cleaning an oven involves a scrub brush, water hose and about 500 gallons of water. Yeah - he’s old school.
Luckily, I noticed the oven was SOAKING wet (but super clean & looking like new), so I tossed a space heater in the oven, set it on HIGH then covered the entire oven with a tarp. After running all night, the oven was very, very dry the next day. This is NOT a curing method - just a drying method AFTER the oven has been cured.
Side note - if you have to do this, make sure the butt end of the space heater is sticking out of the oven / tarp as the thermostat in the space heater will turn the heater off once it reaches a specific temp. Periodically check on the heater to make sure it is running…
Hope this helps!
It worked for me -