39" Corner Build in Norway

[MikeH]

Decided a couple years ago to start an oven, and Corona complications got in the way a bit. I got my stand built, a couple of weep holes in and as I started sourcing my materials, it stopped up. After finally finding some FoamGlass in country last week, I decided there is no time like the present to get it moving again. (Here FoamGlass is used more in building roads and backfill so sheets were really hard to find.)

Of course in the wait, I learned a bit more and have started second-guessing some of my original design decisions, so have a few questions that I hope to get some help with.

1. Moisture is a fact of life here - days of misty weather will make it impossible to keep everything really dry, both in build and after. We don't have that much heavy rain to worry about. I'll have tiles as the base layer, but should I put waterproofing on top of my slab, or will the tiles and foam glass be sufficient?

2. Locally they recommend wrapping the CaSi sheets in foil to protect them from rain during the build. I agree with the logic here that it's not a good idea, but I'm concerned about the edges. Any thought to putting a cement based, breathable waterproofing on the edges of the CaSi?

3. The design change I'm considering is the height. I had planned on 2" of FoamGlass and 4" of CaSi. That would put the oven floor just below my elbow. I'm now thinking it would be better 2" higher, so right above my elbow. I could raise it with another layer of CaSi, but will I gain anything other than height with 8 inches of floor insulation? Any opinions if that 2" of extra height is just me over-thinking it? I won't be using it for hours every day, mostly pizza and bread the day after.

4. Last question for now - given the moisture situation, would it make sense to only use FoamGlass under the landing where it will be most exposed? I won't have a proper roof over the enclosure (building restrictions). The FoamGlass is rated for 800 Celsius.

I'm hoping to have everything sourced and shipped in by June and start cutting brick after vacation. Starting before has a very low W.A.F. Also, some of the materials are much cheaper buying and shipping from Denmark, so I'll have some lead times, but will document my build here as it goes.

[fhausback]

I live in the Midwest of the USA and I did not want to worry about maintaining a waterproofing plan on the oven. I see lots of good ideas on here, but I think I’d be worried about it during every thunderstorm or when snow collects on top.

So, I’m building a roof over this thing, and I wish I would have built the roof structure first. I finished my dome a few weeks ago, and am working on a enclosure now, and it is so much easier to cover up nice and tight with the walls in place.

Even though I’m building a enclosure, I still used 2” of foam glass under the entire floor and flue gallery, and added weep holes. I’ve been taught water always finds a way in, and you have to give it a way out.

[Pizzarotic]

1. Moisture is a fact of life here - days of misty weather will make it impossible to keep everything really dry, both in build and after. We don't have that much heavy rain to worry about. I'll have tiles as the base layer, but should I put waterproofing on top of my slab, or will the tiles and foam glass be sufficient?

Ideally you would seal your slab as well, but as you are using the foamglass on the slab then you should be fine if it's not sealed.

2. Locally they recommend wrapping the CaSi sheets in foil to protect them from rain during the build. I agree with the logic here that it's not a good idea, but I'm concerned about the edges. Any thought to putting a cement based, breathable waterproofing on the edges of the CaSi?

I don't know of any breathable waterproofing product?
Probably not a good idea to wrap them in foil either. Any barrier will stop moisture getting out as well, but still a good idea to protect it during the build. Can you use a tarp to protect it during the build?

3. The design change I'm considering is the height. I had planned on 2" of FoamGlass and 4" of CaSi. That would put the oven floor just below my elbow. I'm now thinking it would be better 2" higher, so right above my elbow. I could raise it with another layer of CaSi, but will I gain anything other than height with 8 inches of floor insulation? Any opinions if that 2" of extra height is just me over-thinking it? I won't be using it for hours every day, mostly pizza and bread the day after.

6" of insulation is way more than required and 8" will provide zero further benefit, but if you already have it then why not use it to raise the oven.

4. Last question for now - given the moisture situation, would it make sense to only use FoamGlass under the landing where it will be most exposed? I won't have a proper roof over the enclosure (building restrictions). The FoamGlass is rated for 800 Celsius.

Would probably work fine under the landing but I think you are just complicating it. Best idea is to prevent water intrusion in the first place. If water gets under the landing, it will travel to the CalSil anyway. Seal the exterior of the dome and add flashing around the base under the stucco, fit a weather proof door and keep the water out.

[MikeH]

I don't have the extra insulation yet, so think I'll just skip the extra two inches. I'll just tell myself I'm "making it easier for shorter people" and feel good about it.

I do plan on covering it with tarps and a temporary shelter during the build. I'd love to build a big roofed enclosure, but will have to settle with a roof over just the oven.

On the waterproofing of the edges, I was thinking something equivalent to Thoroseal.

Mike