Wet Floor

[Stephen drew]

Just about finished with my pompeii oven. Built a block enclosure around the oven covered with slate tiles. For the roof I poured a 3 inch slab on top covered with epoxy paint. Druing the last rain storm the floor became wet. Water probably went down the sides of the chimney which was not caulked in time for the storm. I can't seem to get it dry. I have left a fan running 24/7for 10 days and have had numerous fires and it is still damp. You can even see steam rising from the floor bricks as the fire heats up. Even with a large fire the floor temp only goes up to 200 degrees or so when the top of the dome can be 700-900 dgrees. it only seems that the floor bricks are damp not the wall bricks. I worry that the insulation board under the floor is also wet and may just never dry. Any suggestions?

[Lburou]

The way you describe it, there seems little doubt that the floor insulation is not dry....Only multiple, long duration firings will dry it out.

[RTflorida]

Sorry to say, I have been down this road. It took 2 weeks of daily fires with duration times of 5 - 8 hrs each. The first 3 days were a battle to just keep any kind of fire going. I actually had water weaping (continuous drip) from all 4 sides of my hearth support slab, for the entire fist week.
Hang in there and keep building long duration fires...it WILL slowly get better day by day.

RT

[david s]

Allowing some time (say 4-5 days) after firing will allow some of the moisture to migrate to the drier parts of the oven, then you can go and fire again. This takes more time of course, but saves on fuel and firing time in the long run.

[Tman1]

Can you lift some of the floor pieces to allow more air to get/under them to help dry the insulation board? I concur that without direct access, this will be a longer process to rectify.

... and get that joint sealed!!

[Neil2]

Did your build possibly leave a "bathtub" in your structural slab that is holding water ?

In a worse case scenario, you may have to drill up through your structural slab to provide drainage.

For those just starting, it is advisable to make sure your structural slab slopes slightly away from the middle to ensure positive drainage. Water will always find a way in. Trying to make a WFO 100% waterproof is frustrating and probably fruitless.

[david s]

For those just starting, it is advisable to make sure your structural slab slopes slightly away from the middle to ensure positive drainage.

Agree wholehartedly, I always try to do this, it is an important design consideration.

[Stephen drew]

Thanks to all for some really good suggestions. If I can't get it dry soon I might take up a few floor bricks to see if that helps. Funny, but the area directly beneath the fire seems to be the slowest to dry so I have been moving it around. Has anyone actually drilled a hole through the slab for drainage? Seems like a good idea just in case. Any downside to doing this? Thanks again.

[david s]

If you drill some holes in the bottom of the slab, glue some insect screen over them to prevent the entry of uninvited intruders.

[Neil2]

"glue some insect screen over them to prevent the entry of uninvited intruders."

The holes could be as small as 3/8 inch dia. Two or three holes should be plenty. You could screen them as David suggests, or widen the start of the hole a bit to insert these: