Finally getting to building WFO in Calgary, Canada

[shanxk8]

I am using a cheap 2nd hand wet tile saw that I got from kijiji for $25. It is only a 7" blade so I need to cut each brick from both sides. I've found it fairly easy to set the right angle for my brick, then freehand cuts from eyeball or line drawn on the brick.
It is a simple saw with a tilting table, like the linked image below. It would be easier to make cuts with larger saw, but I am making due with it. I suspect I will have more difficulties when I get to the long cuts for the arch brick (& similar)

[Apaulo13]

I'm looking forward to seeing how your oven turns out. Still at the tossing the idea to build around in my head. Just north of you in R.D.


Looking good. I may have missed it but what are you using to cut your bricks?

[shanxk8]

My boxes of CF are still sealed and stacked in my garage for the time being. Sounds like I will be doing some reading before I get to insulating my oven.

That is still a little way of for me. I only just started to mortar bricks this weekend. Got 1 & a bit courses laid in about 3 hours.

[Apaulo13]

The material we use in our furnaces isn't the superwool, good old KOwool. It's been my experience (as a journeyman insulator) usinig superwool that it melted like cotton candy, so we stopped using it (I'll check though, we had some heat stress guys leave an open box of it here at the plant and it's been raining). Perhaps it has now been improved. But you're right it is best to check the MSDS for the product you choose to be sure what precautions you should take to protect yourself. Products like KOwool are still old style CF.

[david s]

The new generation of CF (of which Superwool is one) has been exonerated as a carcinogen. The older stuff was classified as a class 2 which means tumours have been detected in lab rats exposed to large doses, but none reported in humans. Superwool is bio-soluble but when it gets wet it seems to dry out ok with no deterioration. Check the data on the product you use.
We have the Germans to thank for this development as they banned the use of the older generation CF

[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

[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))

[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]

Great idea

[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]

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.

[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.

[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.

[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]

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.