possible humidity problem?

[prosehack]

Hey All,

I have a casa2g which is giving me a problem. The area between my fire bricks, sand and foam insulation board is constantly wet. After I cure the oven, in a day or so (with or without cooking use) the area above will be wet again to the touch--to the point of making any embers or ash very mushy. I am in Texas and didn't know if the humidity had anything to do with it. At first I thought it was a leak in the dome or even the surrounding structure, but I have taken steps to seal the structure with a waterproofing membrane; this problem also happens when it does not rain between curing and the following days. I'd appreciate any info or insight anyone might have because this problem is really throwing me for a loop.

The actual physical layout of the oven is: the oven sits on a concrete block 3 wall structure with a 5" reinforced concrete hearth/platform. I continued the blocks from the structure above the oven and capped them with flagstone--the overall appearance is very squarish if you are trying to visualize. I have since applied a waterproof membrane across the top of the flagstone to prevent any water from coming in around the flue or seaping into the flagstone or mortar joints.

[brickie in oz]

It sounds as though your oven isnt cured properly yet, how have you cured it?

[texassourdough]

Is rain collecting on horizontal surfaces of the supporting structure/hearth and seeping into the hearth area? (That is one of my challenges and why I am going to switch to a roofed cover.
Jay

[prosehack]

hey all,

each time i have cured the oven based on the directions in the manual--over five days with increasing temperature fires. it always seemed like it was fine. afterwards, sometimes the door would be closed or open and the flue was also open; a tech at forno suggested covering it when not in use. i didn't know if all the humidity was reacting with the retaining heat inside the oven dome to produce moisture--since the door being open and the flue being open would create a sort of draft to keep fresh air coming in.

for the roof, i have a slope on it for drainage. since the flagstone is so topographical, there might be a small flat spot here and there. water seaping in through the flagstone and mortar joints was my first concern. that is why i put on the waterproofing membrane to seal it. i thought that would fix and address the problem. what throws me off is that this problem also occurs when it does not rain. i don't know if it's because maybe enough water got inside before i put on the membrane and the curing just dries out what is closest to the inside of the oven--and then the foam insulation board underneath just wisks up more afterwards for me to start over. i am starting to think the only way to truly eliminate anything is to pop off the flagstone and look inside between the dome and the structure. i was just trying to avoid that for a last resort because of how invasive it will be.

thanks...

[azatty]

Is there anything nearby or on your slab that causes the water vapor in the air to condense, like a cold water pipe or plants, or a vapor barrier? If it condenses and then runs under your insulation, it could be wicking into the oven that way.

Also, it might simply be stored rain water that has permeated the insulation and/or mortar and takes time to work its way out. Did you put any weep holes in your exterior stone facing? If it is water stored in the insulation and you have effectively sealed it, a long, slow re-cure will drive out the water. If it is exterior masonry that is the culprit, I'd drill some weep holes at the lowest point of the fascia and run the cure cycle.

Did you notice this problem before the weather became wetter?

[azatty]

Originally Posted by prosehack

I continued the blocks from the structure above the oven and capped them with flagstone--the overall appearance is very squarish if you are trying to visualize. I have since applied a waterproof membrane across the top of the flagstone to prevent any water from coming in around the flue or seaping into the flagstone or mortar joints.

Hold on a minute--when you say that you "continued the blocks from the structure above", what do you mean? A picture would be helpful. Is the oven connected to a water-shedding structure like a roof? Or could there be any water wicking from a common wall?

[Neil2]

The insulation layer should have positive drainage at the suspended slab level. You may have to drill some holes horizontally thru your block wall or vertically up thru the slab.

All designs should be based on the assumption that water will inevitably find its way in.