36" build in coastal VA

[nlinva]

The next step is to apply the Superwool blanket layers. I'm going to have either 4 or 5 layers, depending on how neatly I manage to do it.

What is the recommended way to keep these clean and covered in between drying fires and until the outside layer of vermicrete/render gets applied? Do I just put some plastic over them?

[SableSprings]

Keeping them clean isn't the issue, it's making sure the insulation doesn't take on water externally (rain, heavy dew, ...errant sprinkler ). You want the air exposure while doing the curing/drying fires, so after each heating cycle & cool down, putting a tarp or plastic over it keeps it from those possible rain showers. The best way to keep it dry during the initial firing process is to move one of the canopy tents over the build when not firing (chimney heat flow can burn right through them...I know because I just moved my cover back a little from the chimney and the wind moved the heat plume enough to do damage). The advantage of putting a piece of clear plastic over the oven as it cools down is that you'll be able to confirm that you're still driving out moisture based on condensation (on underside of plastic ).

Hope that helps, build looks great, you'll be moving on to baking good eats soon!
P.S. your breather valve/plastic T should work fine without drilling extra holes, a little screen over the ends might be advised just to keep the pathway open.

[nlinva]

It's been a busy week for me. It felt like a bunch of thinks needed to be happen at more or less the same time, but in a specific order, so I'd been trying to prep everything as much as possible to be ready.

First was the chimney transition, from the vent arch to the round hole that will hold the anchor plate for the chimney. The middle layer is thin and although I had mortared it into one piece, it fell apart as I was putting it on, so I scraped away the mortar and re-did it in place.



In the second picture you can see the preliminary placement of the bricks that will support the landing, as well as the pieces of hard insulation that will serve as a bit of a buttress for the arch (which is placed loose on top of the insulation board). I am putting bricks up against the insulation, of course -- by themselves they wouldn't be much of a buttress :-)

[nlinva]

Next up, I cut a bunch of additional hard insulation pieces. I'm going to put those around the brick part of the chimney, and put half-thickness bricks around that; these will get mortared to the decorative arch and help keep that arch stable. At least that's the theory! Apart from this added support, the arch is basically a thin, free-standing thing, which felt too risky.

I am going to have insulation block between the vent arch and the decorative arch. Above that will be additional insulation basically matching the shape of the chimney transition.



The other pieces will go around the other three sides of the chimney transition.



Finally, there will be insulation on top of the anchor plate, around the base of the chimney pipe. (It turns out I cut this too tight, not taking into account the clamp and the spacers on the anchor plate, so I am going to have to recut these).



My original calculation had been that I needed 10 pieces of 18"x36" CalSil board for the bottom insulation. They came 6 to a box, so I ended up with 12. As it turns out, I've now pretty much used up all of it, with only small off-cuts left. So that worked out perfectly!

[nlinva]

Next it was time to put the actual chimney on. I have 2 39" pieces of pipe, for a little more than 6' total, roughly evenly split below and above the roof of the shelter. The roof had had a tarp on it, so I first had to start the actual roofing, putting on drip edges, shingles, etc. until I was close to where the chimney would come through.

Cut a hole in the roof and put the flashing on. It was finicky, because the total chimney length was very unwieldy, and the chimney did not fit easily through the flashing with the clamp connecting the two pieces on, but at the same time, the clamp could not be closed with the connecting point being at its resting place, which is inside the flashing. So I had to put the clamp on above, then carefully wriggle it through the flashing, and make sure it landed correctly on the anchor plate.

I also added some straps to hold the chimney in place and reduce possible torque of the wind being transmitted to the anchor plate and the chimney transition below it.

Finally, I put my flower pot terracotta collar around the chimney pipe. It is just kind of hanging out there for now, but I had to put it on before putting everything else in place. Eventually it will become part of the outer covering of the oven, with a gasket between it and the chimney pipe.

[nlinva]

Finally, today I put up the slate landing. It basically rests on a continuous H-shaped structure of bricks surrounding the insulation blocks supporting the vent arch. In addition, there are outside bricks on the side, plus a few on the front, to provide some additional support. I decided it would be nice to have lips on those outside bricks that the slate could rest inside. The idea is that these will stick out a bit beyond the edges of the slab, as visual accents.

The lips for the side bricks were easy enough, but those on the corners were hard, because the cutting tools are round. I came reasonably close, but had to grind down the thickness of the slate pieces at the corners to fit nicely.

The main front landing is too large for the wet saw to cut lengthwise, so I had to set up a complicated contraption with a roller, and cut twice, starting from the middle, and flipping it over to go to the edge in each direction. Figuring out how to do that cause a lot of headaches, but in the end worked pretty well.

Unfortunately, my oven does not face perfectly straight forward; it's faces maybe a degree or two to the left. This means that the landing almost butts up to the vent landing on the right-hand side, but there is some space (maybe about 3/16") between the two on the left. Not really a problem overall -- I'm going to put some silicone caulk between them anyway as an expansion joint.

In addition, the landing piece turns out not to be perfectly rectangular (it's a slight parallellogram), so I had to do some last minute angle grinding to the outside supporting bricks to make make the piece fit within the lips.

It was quite stressful getting it all to fit as I had pictured it in my mind, but I quite pleased with how it has turned out.

In the fourth picture, you can also see the bricks that serves as a bit of a buttress for the vent arch (as does the slate piece on which they rest), as well as the first brick of the decorative arch, which is tied together with them.

[nlinva]

As I think I mentioned before, all the slate came from an old pool table. I'm pretty pleased with how well that has all worked out. I have two decent-size pieces left over that I had planned to put into the middle two cubby-hole slots in front of the oven, as shown in this picture.



However, I may just finish those slots with a concrete resurfacer/smoother, as I'm doing with the two outside slots. I'm not sure the slate looks much better, though I do like how it is the same as the landing itself. I think I'll wait and see before I make a final decision.



I figure the outside slots will probably be useful to put gloves (welding gloves are essential, I understand) and maybe a brush or something. They are not quite deep enough for any of the real long tools. The center slots can hold a drink or two, plus ingredients or other things that will make it possible to keep the actual landing mostly free to move stuff around on going into or coming out of the oven.

The remainder of the pool table slate are just some fairly narrow strips from around the edges, which have holes in them. Fortunately, there was enough there to cut two small pieces that will fill in the spaces left&right between the vent arch and the landing that became free when I decided to make the landing less deep. One of these two pieces is visible in the second picture.

By the way, the insulation between the vent arch and the decorative arch will get covered with a thin layer of vermicrete and then render, which will fill in part of the 3" reveal there is right now from the vent arch to the dec. arch.

[nlinva]

Question for the experts: What is the best way to handle the bottom of the anchor plate? As you can see on the attached picture, there is a little bit of space between it and the surrounding bricks. My plan has been to seal that with the red high temp silicone caulk, but the gap is narrow enough that maybe leaving it alone is fine too.

[david s]

You haven't detailed how you have secured the anchor plate to the bricks of the gallery. If drilling holes and using fixings, this is the first problem, because drilling the bricks is inviting cracking there. Additionally any fixings are going to expand in the holes exacerbating the issue. If anything bar stainless is used they are highly likely to corrode. Ultimately it's all hidden so once in place it probably doesn't matter that much. If you plan on filling the gap under the plate with high temp silicone I think you will find it will fail, especially if you allow your wife to tend the fire and she allows decent flames up the flue. Some homebrew squished in there would be my preference. Because of all these problems coupled with the ridiculous expense of anchor plates, I don't use them. but use a different idea (pics)

[nlinva]

Sorry, I didn't make my question clear.

I did not use any tapcons or similar. The flat part of the anchor plate is attached to the flat bricks on which it rests with Rutland gasket cement. It may fail, but I'm not sure how crucial it is anyway, because the plate has a circular part below the flat plate that goes down about 1.5" and that will hold it in place in terms of lateral movement.

I ground the surrounding firebricks to fit around that, and there is some space around it to allow for expansion. That means at the very bottom there is a bit of space between the plate and the bricks, maybe about 1/8" on average. I can seal that with silicone, or I can just let it be. What do people think?

[nlinva]

Prepped my decorative arch, the first one I'm tapering the bricks for, as well as having a larger TDC brick. Does the latter traditionally stick forward a bit as well?

Note: the bottom left and right bricks of the arch are already in place, which is why the first bricks shown are not horizontal.

[Giovanni Rossi]

Not sure if it's traditional, but I like the look of the keystone standing a bit proud of the rest. I wish I had done that on mine.

But, would that mean there would be a small gap behind that stone?

[nlinva]

I was thinking I could mortar a thin piece to the back to fill in the gap that would be created my moving the keystone proud.

[Giovanni Rossi]

Some guys have a final render that extends to the back of the decorative arch. Wasn't sure if that is in your plan.

[nlinva]

Yes, I will have a render that connects to the decorative arch, but I think it makes sense to fill that particular gap with a piece of brick to help the structural integrity of the arch.