Finally getting to building WFO in Calgary, Canada

[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]

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.

[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]

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]

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)

[shanxk8]

Before I progress too far with laying my courses, i wanted to seek input if my vent & inner outer arch makes sense to the experienced builders. My inner arch (attached to dome) is planned to have straight sided that meet a semicircle arch with a radius of 11.5". These will be full width (4.5") bricks, cut to the taper to make ~3/8 inch mortar joints.

I intend to cut an "L" out of the front outside corner of the inner arch. I am thinking this would be 1 to 1 1/4" deep (in horizontal direction) and 2.5" down in vertical direction. The outer arch would sit on the "L" cutout with ceramic rope for thermal break. I plan that the outer arch will be a full semicircle, with radius of ~13.5". This would require a cutout similar to the "L" on the vertical portions of the inner arch, to accommodate the outer arch. The outer arch would be made from a 9" & 3" length bricks, but use 3" width (in same direction as 4.5" for inner arch). The 3" wide brick is where my question resides and is to try to make the vent landing more compact.

My current plan would make the outer arch 11" deep inside the cavity and 12" deep on top. The top 12" depth to accommodate chimney mount on top of vent.
I then tried to sketchup my thought on how the s-shape vent/flue would work. The s-shape part that deviates from the outer arch would be ~6" deep to match the 6" chimney pipe ID. The front decorative arch will likely be plain red brick (not in sketchup drawing).

I am wondering if anyone thinks that having an outer arch of 3" wide (?tall?) bricks as i have planned will be an issue?

In the attached sketchup, red brick would be inner arch keystone and blue brick would be outer arch "keystone".

Thanks,
David

[JRPizza]

Can you show a side view? I'm having a little trouble visualizing what you are doing? Not sure why you want to make your bricks 3" tall. You probably want to build a reveal against/above your inner arch, so if it is around an inch you can accommodate the reveal and the "L" and still do a full height (4.5) brick - you can see my L bricks in the picture. They extend above the inner arch to provide a reveal, a heat break, and an overlap/extension over the inner arch.

[shanxk8]

The 3" tall brick is to due to thought in my head that my arch with exterior finishing (insulation & stucco or brick) will extend past edge of my hearth if I use 4.5" tall bricks (that become 4.5" wide at bottom).

I will pull a cross section from my sketchup to illustrate the 3" brick.

[shanxk8]

Here's a cutaway picture, red = inner keystone, blue = outer keystone

[shanxk8]

The reveal i have on the inner arch is 2" currently. Rereading your post, it sounds as though you suggest I could reduce this reveal to 1" (this would increase outer arch to 4", at which point I might as well just leave a full 4.5" wide brick if it fits.

Did I understand your post correctly JR?

[JRPizza]

Yes. There is quite a bit of opinion of reveal size, but I find my one inch to be just fine. Your mileage may vary, as they say.
I had some concern, as although my bricks were full height, I had some that were just over 3" fore/aft to keep my landing at 1.5 brick total and obtain the vent opening I wanted. I was worried I needed "deeper" bricks for stability, but it came out fine.

[shanxk8]

JR, if I were to modify the reveal to 1", I suspect I would not want to cut the "L" to leave only a 1" ledge on the inner arch bricks, correct? Better to make equal size "L"cuts out off both the inner (cut from top) and outer (cut from bottom) arch bricks?

[JRPizza]

I started with half bricks, so they were 4.5X4.5 looking from the side, and I made my cuts 1.25 inch from the right side (in the pic) and 3.25 up from the bottom, to give a 1.25X1.25 projection that went above and over my inner arch, if that makes sense the way I explained it. Have a look at the first picture. The second pic is the L cut bricks for the upper part of the arch, and the last pic shows the lower part of the arch and how I angled those bricks. When I did it, I thought I had it all figured out, then remembered I had to shorten the bricks to account for the mortar.
Let me know if this answer makes more questions

[shanxk8]

That answer makes sense. Cutting only one set of arch bricks does sound smarter in that it is less cuts to make. If i'm making a 3.25" deep cut i will have to break out my grinder because my wet saw (for tiles) will only make a 1.25" deep cut.

[JRPizza]

Even with my 10" saw, I still had to use the angle grinder on each brick - a good masonry grinding wheel makes short work of those firebricks.