Finally getting to building WFO in Calgary, Canada

[UtahBeehiver]

Great start on base. Looks like you are leaning again towards CaSi board, with an igloo shape, you need to mitigate possible water from the base heath from soaking the CaSi. You can still drill some weep holes in the base to help any water that may migrate in (especially easy while cement is green) Another solution of a recent build was to raise the CaSi off the heath using split concrete pavers. Can't remember who did this and whether he place a water proof membrane between splits and insulation. I used FoamGlas as the base since it will absorb water but it is as expensive as CaSi board. Again another option is a V or Pcrete layer, Key is to keep water away from the CaSi board.

[shanxk8]

Would the eventual igloo enclosure (vcrete & stucco) prevent water from getting to the CaSi? Also, what about putting a small border/dam of concrete around the CaSi board once it is in place with floor on top? (or a temporary barrier)

Based on your comment here (& in another thread) I now plan to drill a few holes in the concrete hearth as well.

[shanxk8]

BTW, you, Gulf, & David S are such amazing resources to this forum. You're nearly always the first to respond with great information.
Thank you!

[UtahBeehiver]

What I mean by enclosure is the whole oven has a structure around it, ie walls, roof, etc. Not just v-pcrete and stucco over the dome. As you are building you need to tarp the oven anytime there is a chance of rain.

[shanxk8]

To understand you correctly, if the adequate waterproof stucco is applied correctly, i shouldn't have to worry about CaSi board getting wet after igloo enclosure is complete. Rather, the main concern is during construction while the oven is uncovered. (That I can manage)

[UtahBeehiver]

Are you doing an enclosure or not? An igloo (without an enclosure) will be difficult to keep moisture from the insulation coming from the hearth if the insulation is laying right on the hearth surface.

[shanxk8]

I am planning an igloo. I didn't realize from the plans that another layer was needed between hearth and insulation when doing an igloo.

[UtahBeehiver]

If you are referring to the Pompeii Plans, they are several years old and somewhat dated, although a good baseline. Several members have come up with better innovations, ie tapered inner arch, S shaped brick vents, raising the CaSi off the hearth surface, weep holes, vent holes, etc etc. You can place the CaSi directly on the hearth but with an igloo there are numerous posts of members with wet floor insulation. So it is builder's choice but just pointing out what I see crop up often with igloos. But this not just limited to igloos, even enclosed ovens sometimes have the same issues (water coming in from the front opening or leaks in structure and pooling on the hearth floor, but not as prevalent.

[david s]

Another possible source of water entry is that which wicks up from the stand, although in your case it appears so wet that it's unlikely the source. Water on the stand via a garden sprinkler system is often a culprit. Using a sealer over theconcrete slab before replacing the insulation would be advisable in addition to creating a few drain holes through the slab.

[shanxk8]

I got discouraged in my search for CF board or similar, so bought and poured myself an insulating concrete with 50/50 of vermiculite/perlite. I used the 6:1 ratio suggested by David S.

I have a few questions:
1. Does the consistency in the first photo look right? I was very skeptical but now find it had hardened more than I expected. I did not compress the v/p-crete into the form, rather just screeded it to have a "flat" surface.

2. Would rain about 10-12 hours after pouring affect the v/p-crete? It was uncovered the first night because I didn't think it would rain (but guess what). As noted, it seems to be hardening and I have since covered, since it rained quite heavily for the past 2 days. So I hope it will be ok.

Here's a few pics after poured with the form from the upper slab/hearth removed.

[UtahBeehiver]

If the forms are not in the way, leave them on while you work on the floor and dome to protect the edges of the p/v crete.

[shanxk8]

Great idea

[shanxk8]

I did a bunch on brick cutting and test laying which I must say is very satisfying. I hope I might even be able to start missing bricks this weekend. (let me day I am excited!!!)
I think I have my inner arch locate properly to avoid the droop. I'll have to measure how far from center it is {building 36"). It seems correct it at least under 1/2"out. (I dunno how mortar will change it)

[shanxk8]

So the outside edge of my inner arch (as planned) is 18" from dome center (36" ID oven). Does that sound right to you experienced builders?
That seems relative to my IT, it should intersect the to corner of a full brick (9") Keystone. (i shoulda taken a pic))

[Apaulo13]

Hi guys,

Just a word of caution about CF. It's nasty stuff, especially after being cooked. We use it extensively at work. Our minimum PPE is goggles, respiratory and tyvex coveralls with hood, taped at wrist and ankle, up to full face and decon trailer. (We purchase from C&I Edmonton) Once sealed inside oven should be fine. Another option is called Superwool which is magnesium based and suppose to be a safer option, but it's water soluble so needs to be sealed really well.

Darcy