Barrel Vault in So. Cal.

[Tscarborough]

Re: Barrel Vault in So. Cal.

It needs to be half bonded. Next time you build an oven, do the arch first, then put in the end brick. Even better than having them inside the arch is to key them so that half is inside half is outside and the half outside laps. You want that to be a slip joint, and if it is not keyed fire will escape through the crack.



The firebrick on the right that make up the inner arch are full thickness (2-1/4"), cut so that half is inside and half is outside. I trimmed them flush with the vault later.



Like that. I also angled the inside for better airflow on the top of the arch.

[WJW]

Some more progress and a design change

After having built the side and rear walls...and then having started the first arch in the "normal", non-half bonded fashion...I then heard some input from Al and Tom about not half-bonding. I also heard from some who pointed out that there are a heck of a lot of Alan Scott style ovens out there (which are not half bonded) and they seem to be doing just fine.

Personally, I think it boils down to preference more than anything else, but it makes sense to me that a half-bonded design would be stronger. Since I live right smack in the middle of earthquake country...and since I am employing an unproven method of buttressing (insulating block butted up against concrete block), I think it makes sense for me to go with what appears to be strongest.

So I broke out one of the four bricks I had already laid in the first arch (the others were set to the point that I was afreaid I'd break something else loose by pounding/prying them out), and I started going with the half-bond.

Since my brick-laying skills (or lack thereof) are such that I need to be able to clean up as I go along, I decided to borrow a page from the Pompeii oven building crowd and use an indespensible tool of sorts more than the normal arch forms. I built the arch forms (poorly) but didn't use them much because I think they are more suited for the Alan Scott style of building independent arches. I did use the forms to give some support to the vault as I was going along, but because I was pretty much laying the bircks free hand, I ended up using shims to support the vault as I went along. The homebrew mortar is sticky enough that I really didn't need an indespensible tool or a form to lay the arch bricks in the vault, but I am afraid that the unsupported nature of a partially built arch is likely to pull the whole thing off the sidewalls if I don't do something to support it as I go along.

So here are some pics...


The Design change...




I was hurrying and didn't notice that I had placed the brick to the left of the keystone at a rather significant cant...then I did a crappy job cutting the key stone. I considered pulling it all out, but decided to leave it as is and clean things up as I bring the vault arch forward. I don't think it will affect performance or strength...and I hope it won't be too visible once I straighten things out and bring the vault roof forward. We'll see...





As always...if anyone has thoughts or concerns, I'm all ears.

Bill

[brickie in oz]

Re: Barrel Vault in So. Cal.

Bill, our oven will be far stronger doing it that way.

Dont they pour masses of concrete over the AS design to keep it all in place?

[WJW]

Re: Barrel Vault in So. Cal.

I'd seen a number of builds with the half bond (yours, Toms, and a couple of others) and I had wanted to do that, but I initially couldn't think of a way to do it without using a big form which covered the entire interior of the vault.

After you, John, and David helped me undertand the benefits of a stretcher bond working with gravity and some of the other inherent benefits, it just made sense to me that the forces from the arch pushing those bricks together would allow that half-bond design to benefit in the same way that gravity strengthens a stretcher bond. As you say, the independent arches tend to use cladding give them some additional strength. But since one of the main things I'm trying to do is minimize thermal mass and maximize insulation, it makes all the sense in the world to go with any technique that allows that to happen while increasing strength.

I had originally decided against the half bond because I assumed I'd have to build a complete "whole-oven" form to do so. That was a deal breaker for me because I am so sloppy with my masonry skills that I need to be able to clean up as I go along. It then occurred to me that I could use an indespensible tool to mostly eliminate the need for a form allowing me access to keep things clean and also permit staggering the bricks in a way that I couldn't figure how to do with a normal partial form.

On another note, that homebrew mortar really does work. Breaking out that one brick (so I could start going to half bond) was so tough after only twenty four hours of curing that there was no way I was going to try to break out the other three. And the stuff is as sticky as can be. Every one of the bricks I placed easily stuck well enough to need no form whatsoever. I lay the brick, hold it for as long as it takes to clean up the excess mortar from the joint, and in that amount of time it is stuck. Pretty amazing how the brick just grabs that mortar even in an almost vertical position.


Bill

[brickie in oz]

Re: Barrel Vault in So. Cal.

Whoooowh, Ladies and Gentlemen, we have a winner.......

[WJW]

Re: Barrel Vault in So. Cal.

Still progressing...

This first pic is a shot of a brick (fourth course on the left not far off vertical) about twenty seconds after being laid. That homebrew just sticks right up to the bricks. No need for a form as far as holding the bricks in place.

[WJW]

Re: Barrel Vault in So. Cal.

Well...I know why most people use forms...

I was so happy about how the homemade mortar was so sticky it would hold bricks which were practically vertical. I forgot that the forms were importatnt for making sure the rise of the arch was the same on both sides...



As you can see, the right side was rising faster than the left. I didn't realize this until about the fourth or fifth course. Then I tried to compensate and ultimately got what you see here. A bit cock-eyed at best... I don't think it's going to affect performance or strength (I hope), but this is not one of those builds where people will be saying, "It's a shame to cover that nice brickwork up."

Oh well, the arch you can see here will be covered and it only looks a little bit odd on the inside...most won't notice it. You can bet that for the chimney and front arch I'll be using the forms I built.

At least it's free standing and I can move on to the next step. (Butressing the sides.)

Bill

[Gary Mots]

Re: Barrel Vault in So. Cal.

I wouldn't even worry about it, looks great to me.

[WJW]

Re: Barrel Vault in So. Cal.

Thanks Gary.

[Tscarborough]

Re: Barrel Vault in So. Cal.

No big deal, you won't see it when it is done.

[Tscarborough]

Re: Barrel Vault in So. Cal.

FYI, the way to prevent this is to do both sides at the same time and level across.

[WJW]

Re: Barrel Vault in So. Cal.

Roger that Tom.

I'm learning.

Bill

[WJW]

Re: Barrel Vault in So. Cal.

Made some progress this week. Buttressed the sidewalls, did my entryway, and planted my San Marzano tomatos.


As some of you know, I'm using three inches of Insblock19 jammed up against reinforced concrete block to both buttress and insulate the side walls. In addition, I am partially compressing a layer of ceramic fiber blanket between the block and the Insblock in order to allow for something which can be compressed in response to thermal expansion. As a final expansion joint, I sourced a product from Harbison Walker called "Pumpable Inswool". It is an insulating ceramic fiber putty which can be troweled into place, dries to a somewhat rubbery consistiency, and is comressible and advertised as being suitable to use as an expansion joint.

All told, I have three inches of board insulation, plus one inch of fiber blanket on the sides. On the back wall I have four inches of board insulation, plus one inch of fiber blanket. Under the oven I have three inches of board insulation. On the roof I'll have one inch of board layerd with three inches of blanket.

Here are some pics.

Concrete blocks in place with Insblock19 and ceramic blanket stuffed between. As usual, plenty of rebar. (If I ever sell this place, I'll feel sorry for the poor SOB who decides he's going to take this oven out.)


Pumpable Inswool.



The entryway. As can be seen, I have offset my entryway to left by several inches to give me a more defined area for the fire, and a straight shot to the cooking area when cooking with active flame.



Finally, I got my San Marzano tomatos in the ground. They're little now, but they'll be ready for some good pizza this summer. I'll get the cages on them this weekend.


Bill

[david s]

Re: Barrel Vault in So. Cal.

Your oven is going to stay hot for weeks. Excellent build.i love it.

[WJW]

Re: Barrel Vault in So. Cal.

Thanks David.

Bill