Idaho 36" Build

[AJH]

More progress in between bad spring weather. We got an inch of snow yesterday after about 4-5 inches of rain over the last week...
I cut the inside dome shape on the bottom of my door arch and now I'm trying to figure out where to cut the top. So far, I'm just figuring it out as I go and cutting them to meet up with the dome bricks. That seems to work out fine.

I got the 3rd ring cut and dry fitted and didnt like how the bottom ring looked. I had the first ring bricks dry fitted together tight and then when I mortared them together the little bit of mortar I put between made the last couple bricks a little wonky. I decided I could take apart what I had done and cut them down a little bit to not have me looking at the error every time I'm cooking in the oven... While I was at it, I decided it was time to finish off the landing in front of the arch. It cleaned up the front nicely and made it look like I actually finished something =) Funny enough, I was under the metal roof pergola cutting the landing bricks when the weather turned from light rain to 1/4-1/2 inch hail with a downpour shortly after... Talk about loud! freaked my dog out and we had to run the gauntlet back to the house to get out of the worst of it.

Heading out on vacation next week, so will have to wait till the end of the month to get any more work done on this. Hopefully, I can get the dome done before the summer heat hits...

[mongota]

I still need to cut the inside of the arch bricks to match the dome. I'm not sure about where to cut the top yet since it depends on where the rings run into the arch... Going to cut them as I go and mortar them in as needed.

That (the dome/arch intersection) was one of the hardest parts of the build for me to conceptualize when I was planning the build. However, once I got to that point in the build and saw the structure rise in front of me, it became so very clear and simple. Instead of me rehashing, check out this post and see if this helps. It's not the only way, but it worked for me.

https://community.fornobravo.com/for...414#post392414

[AJH]

Got some decent progress again this weekend. I had to cut the doorway arch bricks down to 3 inches so that I could bevel the cuts without running then through both sides.. I tried one brick and it just wasn't working for me. Got the joints pretty tight and decided to see if it would hold shape without support or mortar =) first two rings mortared in and the arch is started. I still need to cut the inside of the arch bricks to match the dome. I'm not sure about where to cut the top yet since it depends on where the rings run into the arch... Going to cut them as I go and mortar them in as needed. Doesn't look pretty on the outside but that will be covered anyways. The inside is a little off here and there, but I'm the only one that will ever notice...

[rsandler]

I always just added a rough scoop of brick dust to the standard 3:1:1:1 mix; technically that means I must have been doing 3:1:1:1.2 or something like that. I generally mixed up a large batch of dry mortar and kept it in a plastic tub with a lid, because measuring all the components each time was a drag (plus if you add too much water you have a whole chore ahead to get it thickened up). This pre-mix did not include brick dust because it must be kept absolutely dry, and I was never confident my brick dust met that standard. So I'd add something like 8 scoops of pre-mixed using a 3/4 cup measure, and maybe half that of brick dust. Not sure it made all that much of a difference, but I think it was ever so slightly more workable when I added some brick dust; I also forgot more than once and the mortar went on just the same.

Since you cut your bricks a while ago, keep in mind you'll want to get them relatively wet so that they don't suck all the moisture out of the mortar. Not dripping wet, but you do want them partly saturated. A spray bottle works reasonably well for bricks you've already laid; you could also re-soak the bricks and then let them drip dry a bit before starting.

[david s]

Both clay and sand should be considered aggregate because they are not cementious and the temperature to which we fire does not sinter the clay. If you use the brick dust it will be extremely fine , like clay so consider it as clay, but there will also be little chips, too course for mortar, that require sieving out. Frankly I think the work required is not worth it, but many builders have used it.

[AJH]

When I mix up the mortar, I was going to add in some of the brick dust I collected from cutting the firebricks. Is it best to replace some of the clay or sand with brick dust or add it in as a separate addition to the homebrew recipe?
If it's a separate addition, should I do a full part (equal to the Portland) or some fraction of a part?
The weather looks to be favorable this weekend for me to get some mortar mixed up and set the first couple rings... Overnight supposed to be above 40 degrees F. Hopefully I can get them mortared together and get my doorway arch bricks cut. =) Can't wait to get more progress!

[mongota]

Understood! I can commiserate. I've been working on an 8' tall cumaru fence to enclose my side yard and run a ways down the property line for a bit of privacy. I pick away at it when temps go above freezing. It was in the 40s today so I got a bit more done.

Rained enough over the course of the day to wash away the last of the snow, despite the rain I managed to finish up the gates. I'm happy with the look despite the wet sawdust coating the cut lines!


Keep at it, you'll love that oven when done. I fired mine up yesterday.

[AJH]

Mongo - I'm planning on shimming the door when I start in on the arch. I cut the wood form at 11.25 inches so have room for a decent sized shim under it and still be under the recommended 12 inch finish height for an 18 inch dome. I'm also toying with the idea of attaching another board to the outside face so that the bricks stay flush against it when mortaring them in. I'm worried that the mortar joints might get sloppy though if I do... will probably depend on how tight I can get the joints =)

Still need some nice weather to mortar in what I have and then cut to fit the bricks that butt up against the door arch bricks. The problem is, I get one or two good days to work and then its either raining or snowing for a week or two.....

The day that I cut the 2nd ring it was 65 degrees out... when I packed in for the day, it started raining and stayed that way for a week before deciding to snow. This is what it's looked like for the last 4 days now:

[mongota]

I might have missed an earlier post...but your arch form design?

Make sure it is assembled in a manner that will allow it to be taken apart in place after the arch bricks have been mortared in place over it.

A few builders have built their form, mortared up the arch, then while trying to remove the form out from under the arch they've cracked some of the arch mortar joints.

An easy way is to simply cut an inch (or two) off of the bottom of your arch form then place it on a couple of 1" (or 2") high blocks used as shims. When the arch mortar has cured, slide out the blocks, drop the form down, then pull it out from under the arch. I used scrap wood legs screwed to the form to raise my form off the oven floor.

My arch form was assembled with screws, with enough of the screw heads accessible so it could be easily taken apart when needed. Save the arch form to use as a template if you intend on making a plug door. One less thing to try to measure.

[Dino_Pizza]

Nice looking build AJ, I like the corner design on the base.
Don't let the design dome height get away from you as you move thru the rings. Trust your distance tool. The the 3rd-4th ring (depending on your dome shape) may start really angling inward to transition over, so be ready. Your cuts are great, I'm looking forward to the entry arches

[AJH]

Got the 2nd ring done after a bit of trial and error on cutting the angles... took most of the weekend to get those cuts and a storm came in before I could get the mortar in, but it's starting to take shape! I'll need to cut those shims a bit before slapping on the mortar. The 2x6 in the door is a bit too big and will need to get trimmed back a little before I start in on that part. Weather is back to being super windy and rainy with some snow/hail just for funzies... Waiting till I have a couple days with the overnight above 40 before I mortar.

[UtahBeehiver]

Plus one on Mike's comment.

[SableSprings]

You really only want mortar between bricks in the first chain (thin layers or none with your precision cuts!) When that first chain is laid on top of the cooking floor, it will move differently at that interface...and break/shear any attempt to bond it. Probably won't damage anything mortaring them down but it's a waste of your time. As you fully mortar in the chain on top you're locking everything pretty much together. The entire oven is going to expand/contract with each firing cycle...but the dome design has proven itself to be remarkably stable over the centuries of its use. Great job so far!

[rsandler]

Others who built their domes one top of the floor will have a better sense, but my instinct is that it would be wise to at least set them in a thin bed of mortar underneath, if only so the bricks don't go shifting around when you go to put the next course on.

[AJH]

Got a little progress done with the nice weather we had last weekend. Going to cut the next ring tomorrow and maybe mortar them in place on Sunday...
What's the consensus on mortaring the first ring? The joints are pretty tight and I'm assuming that the weight of the dome will keep them from moving. Should I put a thin layer of mortar between them to lock them in better or place them on a bed of mortar?