Finally getting to building WFO in Calgary, Canada

[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]

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]

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!

[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.

[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]

Finished with the hearth pouring this past weekend, with some much appreciated help from both dads & a family friend. (whom we owe pizza) Who'd have thought lugging around 2600 lb of concrete a few times would be reasonably enjoyable.
Now I have the curing time to finish my search for insulation. I may even have found a source for the Thermogold 12 that Utah suggested. If that plans out, I might begin laying bricks this weekend.
Here are the progress photos of the hearth poor and a test brick layout with my newly constructed IT tool.

[david s]

I know the plans say to cover the blanket in mesh prior to doing a vermicrete layer, but as it's very time consuming I don't add any mesh there.. If your blanket surface looks pretty even you don't really need it. I like to make that vermicrete layer quite lean (10:1), just firm enough to act as a reasonable substrate to work the outer stucco layer against. You want the strength in the stucco, not in the insulation layer.

[shanxk8]

Planning an igloo, so have the CF blanket already. I hadn't thought of using vcrete on top to help with the igloo shape. (I figured i'd do that with the stucco, but it makes more sense to even shape out with insulating material then stucco over that)
Thanks!

For the vcrete, do you need the metal mesh installed before the same way you would with stucco?

[UtahBeehiver]

5 or 6 to 1 verm/perl to cement is a good rule of thumb for hearth base (probably at least 4"). Are you enclosing the oven or is it an igloo? If an igloo a 8 to 1 ratio on the dome over the CF will help you with the shaping and base structure of the igloo. If enclosed, some people have poured dry verm/perl after the enclosure walls are up for additional insulation. Attached is K values of various ratios

[shanxk8]

Looks like the ceramic board option is gonna be really pricey and I'm now leaning towards v-crete.
Time to reread the plans on what is needed for that route.
I guess I'll spend the extra drying time cutting more bricks in advance.

[shanxk8]

Duraboard is the expensive one (i think listed as HPS board on link below). If memory serves, I was told the Thermogold 12 was only available as slotted board (that folds to wrap around pipes).
The options i think i have available from Crossroads are here:
http://www.crossroadsci.com/Technica...ataSheets.aspx

I'm also waiting to hear back on cost from the local Forno Bravo reseller. we shall see, as i hope to use a board rather than P or Vcrete.

[UtahBeehiver]

Duraboard is a AlSi material which will work as well as CaSI which is not inexpensive either. With P or Vcrete, either hold quite a bit of water so even though it is structurally strong enough to lay floor bricks on you will need more than a couple days for the material to dry out. It will be hard or harder to remove the water once the brick floor and dome are in place. So if time is a critical factor then P or Vcrete may not be an option for you.

[shanxk8]

Funny enough, Crossroads C&I is the place i contacted already. I'll have to call them back to ask about CalSil board. Fellow i spoke with identified Duraboard (expensive option) and Mineral Wool board.

[agrasyuk]

Shanx , vermiculite-concrete is light. I'd say 36-48 hours should be enough for structural slab to harden to hold the insulAting slab.

[UtahBeehiver]

I used Distribution International for my CaSi board (Thermogold 12), they have branch called Crossroads C&! in Calgary which provides insulation for the oil and plant industry in Canada. It might be worth while giving them a call to save yourself shipping from the US.