36" Corner Build in Minnesota

[MnDude45]

Thanks for the feedback. I proceeded with my plan today and knocked out the outer arch. I tapered the edges against the inner arch and will fill with cord insulation and fiberfrax.

Another milepost surpassed.

[MnDude45]

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??

[MnDude45]

Well, my question was answered by the arch itself. I went out to fill the hairline crack and remove the form. When I did, the arch cracked in three places. I will have to reconstruct the outer arch.

It's a definite step back but I'd rather it happen now than later. Very disappointing.

[Sixto]

Well, my question was answered by the arch itself. I went out to fill the hairline crack and remove the form. When I did, the arch cracked in three places. I will have to reconstruct the outer arch.

I share your frustration, I've not been able to control mortar cracks either...my plan is to wait till after curing and chisel/tuckpoint the worst offenders... but I know there will still remain structural weaknesses that could be made worse by our harsh winters.

Sixto - Minneapolis

[RandyJ]

Sorry to hear that. But as you said better to have that happen now then later.

[MnDude45]

I was able to reconstruct the outer arch and installed the cord and fiberfrax insulation between the inner and outer arch. I was also able to block out the chimney vent. Good progress today.

[RandyJ]

Looking good. You will be able to start curing fires soon.

[MnDude45]

Spent some time in Texas last week catching up with family. So was not able to progress much until this weekend.

Before the trip, I was able to cut and grind the first platform bricks for the chimney vent.

Yesterday I was able to get them mortared into place. I spent some extra time ensuring it was plumb, square and level.

Today I constructed the side supports for the vent. I decided to build them using bricks cut from a cardboard template and mortared them together before placing them onto the arch. We’ll see if this strategy works or creates other issues. Fingers crossed.

I hope to get the prices into place in the next couple days in order to finish the chimney vent and get the anchor plate installed by this weekend.

[mongota]

Nice progress! I;m playing catch-up on a few threads tonight

I did the same for the transition from the arch to the chimney anchor plate, I mortared my bricks together (two sets of six bricks) in a form and popped the form and the 12 bricks on top of the arch all at once. Once the mortar set I removed the wood form. Worked great and ensured a level and flat surface for the chimney anchor plate.

[MnDude45]

I was able to finish the chimney vent this past weekend. So far, it appears to be holding together well.

Its getting real now as I prepare to get the insulation on and the enclosure layout finalized. I will be posting some questions in the coming days about some of the steps to finish.

[Sixto]

Looks great! Took me a while to figure out what the black crinkly stuff was... garbage bag! I'm looking forward to seeing how you attach the metal to brick if you have a metal flue. I'm doing something very similar to your vent configuration, and tried drilling 4 holes into brick to attach the stainless flue base plate with stainless through-bolts and found that to be a long slow process with a masonry bit. I am also interested in exploring alternative strategies for how to protect this ares around the flue from ice and snow (other than building a canopy above or throwing a tarp over it). My outer layer will be terra cotta tiles, but I won't get to that till next spring.

oh, also any words of wisdom about mortaring-in the 10 curved bricks? Keeping the whole assembly square and level, and preventing the center bricks from tipping-in? Did you mortar the center 3 bricks together before putting them in between the 2 ends?
thanks!

[MnDude45]

Sixto - Thanks for the comments. Regarding your questions:
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1) I'm using the Duratech double walled system with a 10" anchor plate. My plan is to attach with hi temp sealant and anchor with four 1/4"x4" Tapcon anchor screws. I have a Tapcon 3/16" carbide tipped concrete bit for the anchor holes. My biggest fear is cracking the bricks of the vent.
2) I plan to wrap with 3" fiber blanket and build an enclosure with steel framing and cement board so the dome will not be directly exposed to the Minnesota seasons. I'm currently debating the running of the curing fires before or after the insulation. This is a very hot topic for many out here. If I run the curing fires before insulation, I take the risk of the extreme temp changes during curing with the risk of cracks. If I wait until after insulation, I think I may need to build the enclosure to protect from weather.
3) I learned the hard way on the outer arch. I built the arch in one day working from the outsides to the top of the arch. When I got the the final 2-3 bricks, I put pressure on them to get them into place. When I did this, bricks in the middle of both side of the arch raised and became unset. When I removed the form (as outlined in posts 166-168), the arch collapsed. When I rebuilt the arch, I completed the 1st five bricks on each side and let it set. The next day I set the next three bricks on each side and let them set. The final day I spent cutting and placing each of the remaining four bricks with a cross support to finish the arch. It has held thus far with now the weight of the chimney vent with no cracks that I can see.

That's probable more than you wanted to know but let me know if you have any other questions or comments

[david s]

Heat and moisture together will accelerate rusting so any fixings should only be stainless.

[Sixto]

Sixto - Thanks for the comments. Regarding your questions:
"
1) I'm using the Duratech double walled system with a 10" anchor plate.
2) I plan to wrap with 3" fiber blanket and build an enclosure with steel framing and cement board so the dome will not be directly exposed to the Minnesota seasons.
3) I learned the hard way on the outer arch. I built the arch in one day working from the outsides to the top of the arch.

Thanks Chris! I am using the exact same Duratech system, and thought about using screws, but changed to SS bolts after reading comments similar to David's previous post. I'm not sure how Tapcons work, but if they oxidate, and you cant get them in S.S. then I would perhaps try pre-filling the hole with high temp silicone or adhesive and install the screws into that while wet, so there's less chance of moisture finding its way into the space between the screw and brick.

You are doing it right with the enclosure. I have a relatively small backyard, and I want to keep the dome visible, so I'm left figuring out how to protect it, both this winter with stucco only, and also after I add tile. Right now, I'm thinking of using some sort of vapor-permeable, waterproof coating on the stucco, then adding a tarp above that.

Regarding #3, I was asking more about the 10 bricks that make the transition between the arch and the square chimney. But I see in one of your photos that your opening for the anchor plate is square on the inside too, so your 6 bricks in the center are not cantilevered out into the opening... I'm doing something slightly different, and when i set my 12 bricks on top of the arch, the 4 bricks that cantilever in the center, tend to tip into the opening...so I'm thinking of mortaring pairs together before setting them on top of the arch, and also adding support sticks below so they have a chance to hold each other up better. Attaching photo to help visualize...

[MnDude45]

Sixto - What size diameter SS anchors are you using? The specs say to use 1/4” but I can’t seem to find any SS in that size.

On the vent, as you can see in post 173 I placed the front and back arched pieces first and let them set. Then I I cut the interior bricks to size using a cardboard template and mortared them together before placing them on the arch. I cut a notch to rest on the arch with mortar and supported it with a scrap 2x4 until set. Then I did the same on the other side. It looks like you did some nice shaping of the bricks for yours.