Starting my barrel vault

[stonecutter]

Re: Starting my barrel vault

Thermal expansion and joint failure weaken an ovens structural integrity..

Yeah, which is what makes a flying buttress in this application even more funny to me.

[david s]

Re: Starting my barrel vault

Good grief...flying buttresses? It's an oven not a cathedral.

True, but the same principles apply. Thermal expansion and joint failure weaken an ovens structural integrity. This is one of the domes big advantages. For kilns, where the temperatures and expansion are greater, structural failures are more pronounced, but the same applies with an oven, particularly a WFO.

[david s]

Re: Starting my barrel vault

The thrust on the side walls is far greater at the top than the bottom. That is why it needs the support there and why the flying buttress does not even contact the lower part of the walls. Steel bracing supporting the wall in this position is an alternative solution as was discussed earlier, but the problem is that steel is corrosive in a hot moist environment and once covered with insulation is difficult to access to replace or adjust.

With your barrel arch, which has a large radius arc, the side thrust on the top of the walls is considerably greater than a semicircular one and why some bracing or buttressing is required.

[stonecutter]

Re: Starting my barrel vault

Good grief...flying buttresses? It's an oven not a cathedral.

[Tscarborough]

Re: Starting my barrel vault

That just means a poorly designed oven to me. What is the exterior going to be?

[david s]

Re: Starting my barrel vault

The thrust on the side walls is far greater at the top than the bottom. That is why it needs the support there and why the flying buttress does not even contact the lower part of the walls. Steel bracing supporting the wall in this position is an alternative solution as was discussed earlier, but the problem is that steel is corrosive in a hot moist environment and once covered with insulation is difficult to access to replace or adjust.

[gugahulk]

Re: Starting my barrel vault

No, because it is not a mass buttress, it is an adhesion buttress. Without locking the first one in, it will just roll over with the rest of the wall.

how about something like this?

[Tscarborough]

Re: Starting my barrel vault

No, because it is not a mass buttress, it is an adhesion buttress. Without locking the first one in, it will just roll over with the rest of the wall.

[gugahulk]

Re: Starting my barrel vault

The first course is the only one that needs to be interlocked, use halfs or triangles to build it up 3 more layers.

Damm Tscarborough that is a great idea, but I am already in the 3rd course. What if I just used halfs now and morter them into the side? I guess that would not be strong enough right? I wish you would have told me this when I was dying for an idea. I dont want to start over. The picture below was sunday I am up to more courses.

[Tscarborough]

Re: Starting my barrel vault

The first course is the only one that needs to be interlocked, use halfs or triangles to build it up 3 more layers.

[david s]

Re: Starting my barrel vault

I already have the blankets so I bought them already might well use them. I am really short on firewood, so the last thing I want to do is ad more mass, if not I would just ad 4 inches of refractory mortar that and that is it. But I am really short on wood on the long run. I dont want to ad any more mass than I have to. What do you think its the best solution for me?

Probably do the three triangular buttresses on each side around 3" thick for each one, as in your drawing, using 5:1 vermicrete, leave them two weeks to dry, then wrap the whole lot in your blankets.

[gugahulk]

Re: Starting my barrel vault

I think 5 blankets is overkill. Any more than 2" thick gives provides little additional benefit for the extra cost IMO.
5:1 perlcrete will add a little mass. You can't have both mass and insulation. The stronger you make the perlcrete the heavier and stronger it becomes, but the less insulating it will be.

I already have the blankets so I bought them already might well use them. I am really short on firewood, so the last thing I want to do is ad more mass, if not I would just ad 4 inches of refractory mortar that and that is it. But I am really short on wood on the long run. I dont want to ad any more mass than I have to. What do you think its the best solution for me?

[david s]

Re: Starting my barrel vault

Will adding perlcrete increase my mass? in a ratio of 5 to 1? or it will just work as insulation and strength? Remember I am planning on adding 5 ceramic fiber blankets to the vault. I need to make sure they will work great also keeping everything very insulated. I do have the problem of finding wood so I did not wanted to increase my mass if I didn't have to. Please let me know.

I think 5 blankets is overkill. Any more than 2" thick provides little additional benefit for the extra cost IMO.
5:1 perlcrete will add a little mass. You can't have both mass and insulation. The stronger you make the perlcrete the heavier and stronger it becomes, but the less insulating it will be.

[gugahulk]

Re: Starting my barrel vault

Yes that would work. A flying buttress only contacts at the top though. It's advantage is that there is less contact with the wall (less heat loss through conductivity and looks more elegant.

The only way I can think of doing that is casting something out or refractory mortar. But, than I would cover it completely with ceramic blanket. I don't think a brick would be tall enough.

[david s]

Re: Starting my barrel vault

like some triangles casted like this? 3 of them?

Yes that would work. A flying buttress only contacts at the top though. It's advantage is that there is less contact with the wall (less heat loss through conductivity and looks more elegant.