Warning on Hearth Design

[Balty Knowles]

Seems obvious now, but you can't go back to fix it. When I poured my hearth I made it level & with all the rain this winter I got a lot of water inside the oven. The rain water seeps into the floor from the hearth. If I did it again I would have some design for the rain to run off in the opposite direction.

[fxpose]

Re: Warning on Hearth Design

I plan on pouring my landing area with a pitch exactly for this reason. Everything else inside is level.

George

[sjmeff]

Re: Warning on Hearth Design

This is something I really stressed about during my build (based on some posts that I read at the time). I ended up making my hearth level, but the counter in front of the oven is slightly lower and tilted a few degrees forward. Along with a tight "weather" door that I use to keep out rain water, I've managed to keep a dry oven. Fingers crossed that it stays that way.

[SCChris]

Re: Warning on Hearth Design

I decided that the oven house made sense to keep the oven dryer and adding insulation was also a big plus.

Chris

[kebwi]

Re: Warning on Hearth Design

My rather flat hearth was certainly seeping water under the insulation boards during the build. My intent is to get the whole oven locked down tight with surface bonding cement including all the seems where the enclosure walls meet the hearth. God knows how I'll ever the moisture out of there. Hopefully as I fire the oven a few times the heat will evaporate the water up into the oven and let it escape...out the chimney if possible instead of through the dome into the insulation where it'll get trapped under the SBC. Sigh.

[RTflorida]

Re: Warning on Hearth Design

Balty, I feel your pain. If your oven is as wet as mine got last year, you will be weeks drying it out and possibly several days fighting to just get a fire lit.

I had the foresight to pitch my hearth towards the entry about 1/4" from the inside back to the inner arch, knowing every summer would bring hoizontal rain almost daily.....it did not help and it won't help. My experience tells me that any prolonged rainfall that falls on any brick surface that is overtop of your insulation layer WILL wick water. The more it rains, the more it wicks until your entire inulation layer is saturated and then the dome wicks the water from the insulation.
The best solution is a "house" type enclosure with some sort of "awning" or cover over the entry.
Currently I am in the middle of the refurbishment of my oven to make it as watertight as possible without building and enclosure. I poured a new concrete counter, built a new outer arch, added another 1" of insulation and covered the entire dome with a pvc pond liner. Yesterday I covered it all in SBC and hope to get started tomorrow on a stone entry overhang and covering the entire dome with 2"-3" river stones. Not sure if any of this will keep out the driving rains that will begin next month...but I had to try something.

If I can get my phone to take a few good photos (my vehicle was broken into any my good camera stolen), I will post a few pics when done.

RT

[Archena]

Re: Warning on Hearth Design

Hmm, could you mold the surface bonding cement around the base sort of like the 'baseboard' bathroom tiles? That would direct water off the base and onto the hearth (and hopefully off the edge).

As for drying it out, I'd suggest a small fan. Shove it in back and point it toward the door. The circulation will help decrease the humidity - just don't point it in from the outside. You want the air in the oven to go out, not just swirl around inside. A slightly cheaper option is Damp-Rid - or you can combine the two.

Sorry to hear about the theft, RT. That really stinks.

[timo]

Re: Warning on Hearth Design

I think this concern needs to be elevated in the design plans. The water issue really is a tough one for igloo owners, like myself. Must keep water out and away from oven and landing, but it's outside getting pounded...

I have tried SBC and it was the best stuff I've found for the outside-most layer. I have also repoured the landing area with an even greater angle away from the oven.

Next is putting ceramic tile on a pitch away from the base to the block wall. Then use a "weather" door.

The first fire in over four months barely kept itself lit.

Eventually, the only thing to stop the water will be an enclosure.

sjmeff, do you have a pic of your "weather" door? I need to get started on one of those, too.

[sjmeff]

Re: Warning on Hearth Design

Timo - here are some photos of my weather door. It's simply a piece of painted plywood with a 4x4 screwed on the back to keep it securely in place.

Like RT points out, I think it's important not to have any firebrick exposed since they so easily soak up water.

S

[Balty Knowles]

Re: Warning on Hearth Design

After 4 fires I almost got it dried out. I'll try a big fire today to see if it ill get up to temp. I left a 1/4 gap between the floor & the hearth landing for expansion, I think I'll seal it with some compound this summer & see what happens next winter.

[timo]

Re: Warning on Hearth Design

sjmeff, thanks for the pics. I am already starting on something like this now. I redid the landing area with a much greater angle away from the bricks and hope a weather door stops most the rain and snow from sneaking in. My thinking is the rain will be stopped before getting to the firebricks. I would like to add a seal around the top edge, like a weather stripping. I'll get a pic soon.