Mortarless dome/vault?

[edd91]

Dear all,

I'm wondering whether a mortar-less dome or vault is stronger than one with mortar?

I first thought it would be, this would require bricks with angled sides, as you get a perfect keystone structure, but after reading some more, perhaps the mortar serves to distribute compression forces.

What do engineering types think?

[brickie in oz]

Re: Mortarless dome/vault?

I think a mortar less dome is very feasible, once everything is in place it wont go anywhere.

There is an external link on the forum somewhere where a dome is completed with a sand dome form, bricks with no mortar and then bogged over the outside with gloop.

[stonecutter]

Re: Mortarless dome/vault?

A truly mortar less dome would be a very difficult task.... one without a parge, or filling the void under each brick in the course.


I also do no think it would make a superior oven, for a multitude of reasons...practicality would be #1. Omitting mortar may even shorten the service life of an oven too, due to the thermal cycling (expansion and contraction) . Mortar plays many role in masonry construction, (which an oven is) and couple of them are to serve as a protective gasket to the units laid, and as well as a network of masonry ( like webbing ) which adds strength to the structure.

Dry work of any kind, is reliant on friction, weight of the units and gravity to hold it together. Even with a good cladding layer, an oven is a dynamic thing.

I am not saying it is not possible, it would be a cool oven to see....I am a big fan of tight fitting work. But the effort will NEVER be equal to the reward, because the same results can be had using traditional methods.

[edd91]

Re: Mortarless dome/vault?

I thought I posted a reply but perhaps its awaiting moderation, but there is an example of a mortarless vault here, MHA News - 2009 Meeting at Wildacres

[stonecutter]

Re: Mortarless dome/vault?

You're joking right? That oven was completely built with mortar.

The arch was dry fit, yes, but there is a light parge, and the sides are mortared. There is zero benefit outside of conversational for "dry" fitting the vault roof.

[edd91]

Re: Mortarless dome/vault?

Sorry I meant to only talk about the arch

[stonecutter]

Re: Mortarless dome/vault?

Also, note that the oven built was meant to be temporary. That would be an exception.

It is taken for granted (at least by me) that when people plan and build ovens, they want them to last a very long time...and even have some the idea that the oven will out live them.

[david s]

Re: Mortarless dome/vault?

Many kilns are built using bricks without mortar. It allows for free expansion. There is way more expansion in a kiln than an oven because the temps are around three times higher.The problem with using such a method for a dome is that the bricks need to be cut precisely to avoid gaps which will leak heat.

[stonecutter]

Re: Mortarless dome/vault?

Sorry I meant to only talk about the arch

Gotcha. I say go for it if that is what you want to do. It certainly won't matter to pizza. Make sure you insulate well, and if posible keep the roof accessible. One thing a barrel vault has over the dome is that it is MUCH easier to rebuild ( I'm not saying you will have to necessarily) If you dry stack your dome, then it will greatly benefit you to stagger bond your courses, just like the photos. It's tempting to run a row, drop the centering, run the next, etc. That way works but it is not as strong.

So, it will work, yes...is it best practice? no......my new mantra

[brickie in oz]

Re: Mortarless dome/vault?

I thought I posted a reply but perhaps its awaiting moderation, but there is an example of a mortarless vault here, MHA News - 2009 Meeting at Wildacres

You must have maxed out their bandwidth as the page is unavailable.....

[stonecutter]

Re: Mortarless dome/vault?

Many kilns are built using bricks without mortar. It allows for free expansion. There is way more expansion in a kiln than an oven because the temps are around three times higher.

That is true David, and I agree with that engineering, just not for WFO's.

[stonecutter]

Re: Mortarless dome/vault?

You must have maxed out their bandwidth as the page is unavailable.....

It pulls up fine for me every time, maybe because you are in OZ?

[david s]

Re: Mortarless dome/vault?

It pulls up fine for me every time, maybe because you are in OZ?

No, it works ok for me. Not Oz, maybe your computer.
Four things I don't like about this oven...


1. Updraft system, heat will probably be uneven. Probably cool corners. Heat loss out flue.
2. They are curing it in 3 hrs from wet completion.That's asking for trouble in my book.
3. Right angle bend on flue. Poor exhaust.
4. Big heat loss from that air intake under the stoking door, unless it's plugged up for retained heat baking.

Having said that, it probably works pretty well. After all every design is some kind of compromise.

[stonecutter]

Re: Mortarless dome/vault?

No, it works ok for me. Not Oz, maybe your computer.
Four things I don't like about this oven...


1. Updraft system, heat will probably be uneven. Probably cool corners. Heat loss out flue.That is because the builders belong to a Masonry heater organization, and this design is incorporating some of that technology.
2. They are curing it in 3 hrs from wet completion.That's asking for trouble in my book. Big agree here. That is wrong for every reason except two...temporary, one day event.
3. Right angle bend on flue. Poor exhaust. Again, temporary oven....I know a couple members of the organization, in fact my old next door neighbor was one...and he is a leader in the industry, and a master craftsman.
4. Big heat loss from that air intake under the stoking door, unless it's plugged up for retained heat baking.Three times for emphasis....it's a temporary oven. Trust me, these guys KNOW heat retention....that is what masonry heaters are all about.

Having said that, it probably works pretty well. After all every design is some kind of compromise.

Good discussion....your final point is spot on.

[david s]

Re: Mortarless dome/vault?

That is true David, and I agree with that engineering, just not for WFO's.

Can't see why not, maybe not suitable for a dome, Because of the complex tapers, but a braced or buttressed barrel vault should be ok.