36" Corner Build in Minnesota

[Sixto]

I got 1/4" x 3" s.s. bolts at my local Menards. Using lockwasher on top, recessing bottom of bolt in mortar-filled part of brick, so it won't turn when I tighten bolt down. Will cast a sloped cement cap with fiber reinforcement over the whole thing to shed water and snow.

[Mr. Slowhand]

Alright, I know all ovens have cracks but…

I noticed this hairline crack in the outer arch. It’s directly in the middle on the last brick I laid. It runs 2/3 down the front and all across the top. It doesn’t appear noticeable in the back (chimney vent).

Should I be concerned enough to remove, replace the brick and re-mortar before the removal of the arch form? Or just fill and move forward??

Thoughts??

I have the same in my oven. I used a scalpel to remove as much as possible of the mortar, and will add new mortar. It was directly next to the keystone of the arch. Don't know if it was a good thing to do, I just could not bear to see it, it is the only exposed arch towards the outside

[MnDude45]

Mr. Slowhand - It did not work out well on mine. The hairline crack didn't show the issues through the arch. When I removed the arch form, the arch came apart in pieces. Hopefully, you will not experience the same. Overall, I only lost about a day and a half it it appears to be strong now. Good Luck!

[Mr. Slowhand]

Mr. Slowhand - It did not work out well on mine. The hairline crack didn't show the issues through the arch. When I removed the arch form, the arch came apart in pieces. Hopefully, you will not experience the same. Overall, I only lost about a day and a half it it appears to be strong now. Good Luck!

Good info. I wanted to keep the arch form, as I am casting a flue shortly. With this info, I will first remove the arch, see if the thing can stay on it's feet, and than put the (smaller) arch form for the sand mould back. You are right, a day and a half are not a big issue when building these things

[MnDude45]

Alright, I'm planning on building the enclosure around my oven on the concrete countertops. Steel framing with 1/2" Durock cement board with Rock-on fastners.

Questions -

1) For the framing track on the countertops, is there a vapor barrier or concrete adhesive placed between counter and track?
2) I'm assuming stainless steel anchors to hold track against counter
3) The most common widths of framing is either 2.5" or ~3.5". Does is matter for this application?
4) The most common gauges found at Big Boxs are 20ga or 25ga. The 25ga at Menards says "For interior, non-weight bearing walls". Do I need to ensure galvanized and use a 20ga or possible 18ga?

I'm planning on placing the 3" of fiber blanket this weekend and start curing fires but need the enclosure to be fast follow to keep it dry.

Thoughts??

[Sixto]

Alright, I'm planning on building the enclosure around my oven on the concrete countertops. Steel framing with 1/2" Durock cement board with Rock-on fastners.

Questions -

1) For the framing track on the countertops, is there a vapor barrier or concrete adhesive placed between counter and track? Typically what I see is some sort of compressible foam or a few beads of caulk to keep moisture from seeping in at the base. If your studs can be flush with the edge of the counter, I would extend the durock to the bottom edge of counter slab, and seal the edge with caulk. If not, I would add galvanized flashing at the base of the durock, so if any snow piles up against it, it has to climb 4-6" up the back of the durock to make it into the enclosure.
2) I'm assuming stainless steel anchors to hold track against counter I agree.
3) The most common widths of framing is either 2.5" or ~3.5". Does is matter for this application? I would think this is small enough that 2.5" wall studs should be enough, but I'm not a structural engineer and overbuilding won't hurt.
4) The most common gauges found at Big Boxs are 20ga or 25ga. The 25ga at Menards says "For interior, non-weight bearing walls". Do I need to ensure galvanized and use a 20ga or possible 18ga? For sure Galvanized studs, othewise they will rust. Gauge, I'm not sure.

I'm planning on placing the 3" of fiber blanket this weekend and start curing fires but need the enclosure to be fast follow to keep it dry.

Thoughts??

Comments in red above.

[MnDude45]

Thanks for your thoughts. I liked the thought of the galvanized flashing under the cement board. I hadn't thought of that.

What are your thoughts on how to protect the dome during the curing fires? I need to remove the pop-up to run the fires but don't want to leave it uncovered for a week.

I thought I'd insulate and then build the walls of the enclosure to allow a tarp/cover during the night.

[MnDude45]

Curing your oven is an important step in the installation of any brick oven -- whether it is a Forno Bravo precast oven, a Forno Bravo Artigiano brick oven, or a Pompeii brick oven. Heating up your oven too fast can lead to cracks. You have invested a great deal of time, money and energy in your oven, so go slow, and cure your oven properly. If at all possible, don't schedule a pizza party the weekend your dome is finished.

After you have installed your oven, there is still a great deal of moisture in the mortars, hearth concrete, vermiculite, and the oven chamber and vent themselves. Each of these oven components was recently produced using an air-drying, water-based process. Simply letting the oven stand for a week does very little to "cure" the moisture out of them oven. In fact, the Forno Bravo precast oven producer recommends letting the oven stand for a week after it has been assembled before "starting" the curing process. Thicker sections of concrete can take many weeks to cure.

You are trying to avoid two problems. First, any mortar or concrete that dries too fast shrinks and cracks. These cracks can let hot air and/or smoke escape from the oven chamber. Second, if you bring your oven up to heat while there is still sufficient moisture in the oven dome or mortars, you will actually create steam, which can produce hairline fractures, or even cracks in your oven. I heard a story (possibly an urban legend) from one of our installers who used to work with one of our competitor's ovens, where the home owner lit such a large fire in a non-cured oven that a chunk of the oven dome actually blew out the front door. Hmmm. Maybe.

Also, using a space heater can help, but only so far. It is not an alternative to fire curing. We ran a space heater in an assembled Forno Bravo precast oven for two days, then quickly heated the oven up, (don't do this at home -- it was an experiment to see what would happen to an oven that we have here) and we found that we created a very large amount of steam from the oven, mortars and vermiculite, which went on for hours and hours.

To be safe, here is a good curing schedule.

1. Let the oven sit for a week or so after you have finished the dome.
2. Run a series of seven fires, starting with a small, newspaper-only fire.
3. Increase the size of the fire each day by about 100F
200F
300F
400F
500F
600F
700F
800F
4. Let the oven fall back to cool as soon as you reach the temperature you want. It is important to bring the oven up to heat gently, then back down to cold, each time.
5. If you don't have an infrared thermometer, try this schedule:
Newspaper only
Newspaper and a little kindling
1 stick of 2"x3"X16" wood
2 sticks of wood
3 sticks of wood
4 sticks of wood
5 sticks of wood

James

Also, here is the firing post from several years ago...Any other suggestions from the group??

[Sixto]

..... I need to remove the pop-up to run the fires but don't want to leave it uncovered for a week.

I thought I'd insulate and then build the walls of the enclosure to allow a tarp/cover during the night.

I like that idea, hadn't thought of removing the pop-up myself (tent on fire!)and I have no permanent surround planned. When my time for drying fires comes, I'll lash some 2x2's together to make a teepee of sorts using the tent-top over the dome (but not over the flue) to make sure any water sheds off it, instead of pooling on top.. thanks!

[Mr. Slowhand]

Mr. Slowhand - It did not work out well on mine. The hairline crack didn't show the issues through the arch. When I removed the arch form, the arch came apart in pieces. Hopefully, you will not experience the same. Overall, I only lost about a day and a half it it appears to be strong now. Good Luck!

He, was just clearing to fill in some cracks, when entire actually the entire arch was loose. It came in 2 pieces. I still have the arch form, so cleaned it, soaked, and re-mortared it. So glad you told me what you did, so I checked for structural integrity before I continued.
Only one evening lost, TBH, not a biggie

[MnDude45]

Mr. Slowhand - Sad that you had that happen but grateful you were able to catch it at this time rather than later. Keep moving forward, Marko. You are making great progress.

[MnDude45]

Today i was able to trim the excess floor and insulation in order to prep for dome insulation. Also, I installed the chimney anchor plate. I decided to use the 1/4 x 4” Tapcon anchor screws. I bought a new hammer drill from all of our favorite store (Harbor Freight) and installation went well. On to dome insulation and curing fires soon. So much excitement and terror at the same time as it is getting very real. Again, is it the light at the end of the tunnel or the train??

[MnDude45]

Quick question…when applying the ceramic blanket to the dome, did anyone use an a hi temp adhesive or just lay it on and hope there’s not a strong wind? When I’m done, I’ll use a thin galvanized wire to hold it in place. It’s really just for the time putting all three layers down.

[SableSprings]

Just put the layers of batting over the dome...no need to use adhesives of any kind. Since you should go through the curing process before applying stucco over the blanket, you can lean some bricks around the perimeter & couple on top to hold it in place if you choose not to lay chicken wire or metal lath over it. Just remember to wear a good mask, gloves, & goggles to protect your eyes...the ceramic fibers can be very irritating!

[MnDude45]

I just laid the blanket over the dome and propped them on with scrap 2x4’s. It worked well until I determined I was going to run short on blanket. I had enough for 2.6672 of the 3in to cover the entire dome. Ugh! I’ll have to run tomorrow and get another roll.