barrel vault oven cladding

[chickade]

I noticed that many barrel vault ovens have 2-3 inches of concrete cladding, not only for mass but for reinforcement of the arch and wall structures. The walls need reinforcement while the vault is being constructed. What are your thoughts about later, permanent reinforcement- cladding or otherwise? How likely is it that my oven vault will collapse without it?

[david s]

Re: barrel vault oven cladding

Because of the form of the arch it is virtually impossible for it to collapse, provided the walls it thrusts against do not move. Gravity pushes the bricks closer together. The larger the radius is though, the greater is the sideways force on the walls. As you have vertical bricks for the first course you will probably need to further increase the strength of the walls either by steel bracing or buttressing or both. Also the end walls should be inside or under the arch so there is less pressure against them from the expanding heated arch.

[brickie in oz]

Re: barrel vault oven cladding

In your pic you have used soldiers, there is no strength in soldiers and is inherently a very weak way to do the first few courses.
The vaulted roof will want to push outwards from the top of the arch, the soldiers will let this happen.
Laying the bricks in running bond is far stronger.

Also, how do you intend to bring it all together with the angled walls at the front of the oven?

[Tscarborough]

Re: barrel vault oven cladding

I don't trust simple cladding to hold a soldier or sailor (you have a soldier) course. I think it needs a pre-tensioned or a compression ring (which can't be done practically in an oven with an opening). This is how I did a pre-tensioned ring with a sailor course.

The first picture shows the posts, one on each side of the entry, consisting of 3/8" rebar drilled into the slab. 9 gauge hot dipped ladder (horizontal reinforcing wire for block-laying) wire was wrapped around the dome between the posts, spaced from the firebrick by firebrick shims, then tensioned.

The second picture shows the cladding of home brew refractory concrete in place, the third shows it with the forms stripped.

[chickade]

Re: barrel vault oven cladding

Thanks very much for your comments. I can see that I have made the mistake of following plans for an Alan Scott oven, when I don't want the cladding and mass that goes with it. The mass is part of the structure, so the structure doesn't work without the cladding.

Could I use supports like WJW used on his barrel vault oven? It looks like he has insulation next to his walls to help support the arches, and concrete block with rebar keeping the insulation stable next to the walls.

How would you suggest I go about putting the back arch over the back wall? Should I build the back wall and then cut the bricks to fit the arch, or should I build the arch first and fill in the wall under it? My ability to cut curves is limited.

Thanks.

[Tscarborough]

Re: barrel vault oven cladding

The other way to support the oven walls is to build an outer masonry wall then fill between the oven and it with prelcrete at 6 to 1 or 8 to 1. That is the method used by some Italian oven builders.

[shuboyje]

Re: barrel vault oven cladding

You could also use a steel harness, as is common in large commercial barrel vault ovens. Here is an example:

STOVEMASTER - News

I would personally put 1/4" ceramic fiber between the masonry and the steel just to give a bit of an expansion gasket if using this method.

[Tscarborough]

Re: barrel vault oven cladding

Yes, but to me that is an in-elegant solution. Here is another trussed oven, built by a professional mason (and a very good one at that):

[Tscarborough]

Re: barrel vault oven cladding

Here is the (almost) finished oven:

[Tscarborough]

Re: barrel vault oven cladding

I see they offset the opening in that oven, Shuboyje, I am glad to see that, since I plan to do the same on the next oven I build.

[Laurentius]

Re: barrel vault oven cladding

Hi Chickade,

From looking at your floor and hearth, you're using Scott's mass concept. What are you using for hearth insulation, other than fire bricks? Look like too much mass for me?

[chickade]

Re: barrel vault oven cladding

I like the idea of steel trusses, as it seems simple, though I would have to find someone to do the welding.

Can you comment on what someone who has limited masonry skills could do about the back of the oven and it's arch? I understand that using the Alan Scott method would make the oven prone to cracking at that joint between the oven back wall and and arch.

[shuboyje]

Re: barrel vault oven cladding

There would be no welding needed. 2 pieces of c channel, some all thread rod, a couple nuts and washers and you are set. Biggest pain will be drilling the holes in the steel for the rods.

[david s]

Re: barrel vault oven cladding

I see they offset the opening in that oven, Shuboyje, I am glad to see that, since I plan to do the same on the next oven I build.

looks dead centre to me.

[david s]

Re: barrel vault oven cladding

I like the idea of steel trusses, as it seems simple, though I would have to find someone to do the welding.

Can you comment on what someone who has limited masonry skills could do about the back of the oven and it's arch? I understand that using the Alan Scott method would make the oven prone to cracking at that joint between the oven back wall and and arch.

To avoid the expanding arch tending to push the back wall out, the top of it should sit under the arch. Kilns built with this configuration should be done that way, although they are subject to greater expansion. the longer the arch is the greater the expansion and therefore the more of a problem it is.