36" build in coastal VA

[nlinva]

Thanks for the suggestions, Giovanni Rossi ! I've done some more searching through the forum, and come to the conclusion that it is most straightforward simply to butt the slate up against the firebrick oven floor. If it ends up causing issues, I'll replace the slate by soapstone or thinner firebricks -- should be straightforward enough.

Also, I love the picture of the lateral support nearing the top of the dome! So cool! I will probably make use of something similar when I get that far. Today I covered the arch, which required some cutting/grinding to get the bricks the right shape, but it was not as difficult as I had expected.

On the other hand, now that I have a full round course, both non-circular and non-level issues are more visible. Going to try to get to level and circular over the next course or two, before things get too vertical!!

Will try to post some pics tomorrow; my phone was low on battery today, so no pics.

[Giovanni Rossi]

Thanks for the suggestions on how to prevent bricks from sagging down!! I have a few thin cut branches that I plan to start using, though since they're thicker than what Mongo's picture shows, I worry a bit they may tend to slip on the floor. The hook idea sounds promising too; I'll see what ends up working best.

I thought I had more photos of my supports, but this is all I could find. I usually had cardboard protecting my floor. Most of the time it was wet so the bottoms of the sticks didn't slide. However, the tops would tend to slide on the smooth brick surface. I would rest a piece of brick against the stick and that would give just enough pressure to hold it in place. This became less of a problem as I built higher. But, at the top of the dome I was concerned about needing lateral pressure to snug the bricks against the last course. A few craft sticks did the trick.

I'm wondering about the best heat break to put in between the slate and the oven floor. I figure if I but it right up against the oven floor, I risk spalling. Instead, I could put a thin rope gasket between the landing and the oven floor, making sure to keep it below surface level, leaving the gap to be filled with ash.

I'm sure others have more experience, but I'm not sure you need a heat break for your landing. Certainly, there is some heat conduction from the oven floor; but, IMO the radiant heat from the fire has greater impact on the temp of the landing. Certainly, the distance of the landing from the dome is a factor. I'm curious what others think.

[nlinva]

Thanks for the suggestions on how to prevent bricks from sagging down!! I have a few thin cut branches that I plan to start using, though since they're thicker than what Mongo's picture shows, I worry a bit they may tend to slip on the floor. The hook idea sounds promising too; I'll see what ends up working best.

I've also started to think ahead to the vent landing. I am planning a 2" reveal around the inner arch, and a 1.5 brick depth. This would make the landing 13.5" x 22" (with the 13.5 potentially lengthening a bit depending on how I bridge the thermal break).I have an old piece of pool table slate (3/4" thickness) that should be large enough to make the vent landing, the front landing, and two side pieces for work area. This weekend I plan to cut the slate to the desired sizes for those pieces. My plan is to rest the vent landing on additional insulation (I have some boards left over) to raise it up to be level with the oven floor. With the slate being much thinner, it should also be less of a heat sink.

I'm wondering about the best heat break to put in between the slate and the oven floor. I figure if I but it right up against the oven floor, I risk spalling. Instead, I could put a thin rope gasket between the landing and the oven floor, making sure to keep it below surface level, leaving the gap to be filled with ash. I could also get a hollow stainless steel tube, circular or square. I like the idea of circular, with the thought that it would minimize direct points of contact between the oven floor and the landing. In some older forum builds, I see that square tubes filled with insulation material seem to have been relatively common. The tubes I was thinking of would be too small to fill with insulation, so would just be air-filled. Does anyone have any suggestions or specific builds I could look at that have done something similar?

Where the vent landing meets the front landing I'll want another heat break, I think, but that one should be much simpler, and probably can just be done with some silicone.

[rsandler]

Another technique for stubborn bricks in the final courses is to make a hook out of some heavy wire (e.g. a coat hangar), connect with a string to some kind of weight (e.g. a brick fragment) and hang that on the troublesome brick. I apparently didn't take pictures when I did this on my oven, but searching the forum for "hook" turned up a picture from this build that gives the idea (looks like that builder tied off the string somewhere, but just attaching to a brick is way simpler): https://community.fornobravo.com/for...883#post410883

[mongota]

Coming along nicely!

When I got to the higher courses I found it useful to use some thin pieces of wood as brick props. They didn't really carry much weight, they just prevented brick creep.

[nlinva]

I've added another course or two, and have put in place the starting bricks for the course that is going to cross the arch. That's going to require a fair bit of finicky cutting -- I'll need a bunch of thinner bricks near the top of the arch. Apart from the few bricks I already put up, the remainder of the course is going to be thirds of bricks rather than halves.

I also realized that I've allowed a bit of a droop where the courses meet the left of the arch, so I'm going to have to work to adjust that over the next course or two.

I did some cleaning today, on the front of the arch and the bottom several rows inside. Pretty happy with how doable it was and what a difference it makes!!

[rsandler]

having needed to do a lot of cleanup on my recent oven, I agree with Giovanni--do your cleaning sooner rather than later. End of the work day is easiest (but be careful of pushing too hard on newly-mortared unsupported bricks). Vinegar will be largely sufficient, but the amount of elbow grease required to get the mortar off increases rapidly as the stuff cures. If you wait until the dome is finished, you'll want a chisel more than a brush :-P.

[nlinva]

Thanks Giovanni Rossi and Toiletman for the recommendations on daily cleaning. I will start doing that from now on -- I have more than enough rags, so no worries there.

I was looking at your build pictures just now, Toiletman, and you do have some spectactularly clean-looking bricks on the front arch. I doubt I'll be able to get anything close to that!

I did not get as much done as I'd hoped today, but still put in close to another course, in addition to sawing the bricks for the next course. May get up early tomorrow to get those placed before the regular workweek starts.

And yes, I'm Dutch (not just roots/heritage, but born & raised); that's what the NL in my account name ("NL in VA") is for. :-)

[Toiletman]

Toiletman Yes, looking at your pictures I see how interlocking in that way can make sense. It may be easier to do when the entry walls go up straight for the first few courses, as in your build.

Ironically, I had decided that interlocking with the dome courses might weaken the arch's own structural strength, but I think you're right that it would strengthen the connection between the arch and the rest of the dome. In the end it's probably "lood om oud ijzer" :-)

"lead for old iron" indeed. Dutch roots or heritage?

As already mentioned by Giovanni Rossi most people clean at the end of the day. In my case I had a bucket of clean water and an old rag, and after finishing the mortaring I'd take an hour or so to relax and let the bricks set, and then afterwards clean up with the wet rag. If you rinse the rag a lot and make sure you don't push too hard into the joints you can get your bricks very clean. After and hour and especially on closed loops you cant put very serious force onto the bricks, but you also don't have to treat them as if they were a newborn. You can even redistribute some mortar from the 'highs' to the 'lows'. Or at least I manage to do that, don't know yet if they'll actually stand up to the firing temperatures yet.

Also: all your courses going up are much, much more accessible than when you've actually finished your dome.

[Giovanni Rossi]

nlinva I believe you will find most builders clean the inside of the dome at the end of each work day. It's just easier. It looks like your mortar joint are pretty tight so you don't need to worry about digging out any mortar. You'll just want to let the mortar cure a little and be careful not to disturb any bricks. Just keep rinsing and using a damp sponge until the haze is off of the brick surface. An abrasive pad will work on mortar that's not fully cured. Beyond that it gets more difficult. On other projects I've found a brass bristled brush can be useful. As a last resort, I've used some gentle scraping with a sharp putty knife. I'm not a fan of introducing chemicals. At the end of the day, as long as there aren't patches that risk flaking, it's just cosmetic.

[nlinva]

Thanks for the tips UtahBeehiver ! I've already had to put in some smaller bricks to keep joints staggered (you can see them in the picture); I've just put them in where it seemed necessary. You're right that it would be neater to try to keep them over on the front where they won't be seen, but that would require a lot more precise planning. I've also already been beveling the bricks; I think there is one noticeable inverted V in the picture, which was an oversight on my part, but mostly I'm pretty happy with how the joints look.

As for anchoring for the next day -- I've done that too, in that the highest course I've started on is unfinished, so I can start today connecting to that. But I should've also put up a brick or two for the next course; I'll be sure to do that going forward (and I'll start with those today, so that when I'm starting on the next course they'll already be mostly set).

Do you have any suggestions for cleaning the bricks? From my reading of the forum, people seem to use muriatic acid (I'd like to avoid that) or vinegar (which I'll try first), but I've not been able to find whether it matters how long I wait to do it. It would be easier to do it all at once, but if the cleaning works much better the fresher the mortar is, I could do it after just a few days.

[UtahBeehiver]

Here are a couple tips. First, at the end of the day, lay one or two bricks on the next course and let them set overnight. This will give you an anchor to work from the next day and you don't have to worry as much about brick moving laterally. Second, there will need to adjustments to the brick widths, in order to keep staggered joints. Do these correction on the front half of the dome where the really cannot be seen. Save the best bricks and work for the back half of the dome, this is what you see when you look in the oven. Third, you will start to see what we call and "inverted v" joint as you go up. You really only need to cut off the conflict points at the front of the ID bricks, not necessary to cut the a full length bevel, mortar will backfill the back side.

[nlinva]

Today I did the first non-horizontal courses (courses 1 & 2 were both flat). The IT is very handy, but so far I'm using it mostly to check that the bricks are positioned right. For courses 3 & 4, the bricks were still close enough to horizontal that they did not slide inwards when placed. On course 5, which is about half done, a few of them are just beginning to do so; time to switch to using the IT also to hold bricks in place when first positioned.

Overall, things are progressing smoothly. Tomorrow I hope to get courses 5-7 finished; I have lot more time to work on the oven over the weekend than during the week.

Question: there are lots of mortar smudges on the insides of the bricks; I will want to clean those, of course. How long can I wait to do so? Should I do it right away, or can I hold off until the whole dome is finished? And what is the best way to clean them?

[nlinva]

Toiletman Yes, looking at your pictures I see how interlocking in that way can make sense. It may be easier to do when the entry walls go up straight for the first few courses, as in your build.

Ironically, I had decided that interlocking with the dome courses might weaken the arch's own structural strength, but I think you're right that it would strengthen the connection between the arch and the rest of the dome. In the end it's probably "lood om oud ijzer" :-)

[Toiletman]

Yesterday I did the first mortaring, using the 3:1:1:1 homebrew formula.

It's definitely a learning process. The first batch of mortar was a little too wet; some bricks were a little too wet, some a little too dry, etc. But I think I'm getting the hang of it (fingers crossed!). Despite the heat (around 90F), the mortar remained quite workable for as long as I needed -- possibly because it's so humid here right now. It probably helped that I used chilled water to mix it, as recommended in several places on the forum.

I put in the first two courses, one thin, one normal-size, plus the inner arch. I ended up having to taper the bricks on either side of the TDC brick a little bit, but other than that everything seems to have gone smoothly. Today I removed the form (very glad I had raised it on some shims, because otherwise it would've definitely been stuck!).

I had a little mortar left over, so I put in the first 2 bricks of the next course, which will be the first to curve inwards. I'm thinking I'll need to build a jig to standardize the taper/bezel. I thought I might be able to do it by eyeballing, but I think a jig of some sort will be more efficient.

Wow, ambitious to start with the arch! But great progress!

For my arch I opted to cut each stone to width towards the dome while laying the courses such that the arch bricks would also interlock with the dome courses for added structural strength. But I guess you are past that station now. Don't think it really matters.