Help with modular oven - decorative arch.

[stonecutter]

Re: Help with modular oven - decorative arch.

What I'm not saying, is that the outer arch doesn't need to be anchored like that. It makes someone feel better, no harm done.

[RobDodds]

Re: Help with modular oven - decorative arch.

At this stage the only thing holding the arch in place is the mortar join at its base.I think this is what RobDodds means.
If you look carefully you can see the wire ties in the arch. I usually tie bits of coloured wool on to the ends so you can see them or they get easily buried by the vermicrete layer and are hard to find. They work as a depth gauge too.

That was exactly the problem, I could feel forward movement in the arch as I built it. With the homemade ties in the mortar and in the stucco scratch coat the form came out and the arch is solid. It's made of offcuts of firebrick and it's only 2 inches deep so not a lot of front to back strength.
I keep meaning to post some pictures which would probably have helped, maybe when it's all done I'll do the full series.
Built out a small shelf at the front today with house bricks as stand for a granite countertop. Hope to get the second coast of stucco on tomorrow, then will have to research the final waterproofing coat, although I should maybe get the terracotta tiles fixed to the pad so that the final coat seals onto them for water runoff.
Thanks everyone for your advice.

[david s]

Re: Help with modular oven - decorative arch.

What I'm not saying, is that the outer arch doesn't need to be anchored like that.

It does if it's thin, like mine and Dodds'. I usually wire the arch back against the flue gallery to hold it in position until joining the rendered outer shell to it.

[stonecutter]

Re: Help with modular oven - decorative arch.

It does if it's thin, like mine and Dodds'. I usually wire the arch back against the flue gallery to hold it in position until joining the rendered outer shell to it.

What difference does that make? Have you had one topple over? I'm not trying to start an argument mind you, just understand why you think it's necessary. I've built hundreds if arches of all types. The beauty is it is self supporting, as long as the ratios are correct....and the concern is not failure from being pushed over from pressure applied adjacent to the voussoirs.

[Gulf]

Re: Help with modular oven - decorative arch.

What difference does that make? Have you had one topple over? I'm not trying to start an argument mind you, just understand why you think it's necessary. I've built hundreds if arches if all types. The beauty is it is self supporting, as long as the ratios are correct....and the concern is not failure from being pushed over from pressure applied adjacent to the voussoirs.

Matt,
Think of it like brick veneer on a conventional wood stud built home. There is no lateral stabilty there without wall ties. And, in this case, it can't hurt .

[stonecutter]

Re: Help with modular oven - decorative arch.

Matt,
Think of it like brick veneer on a conventional wood stud built home. There is no lateral stabilty there without wall ties. And, in this case, it can't hurt .

That's different, a veneer on a building doesn't have the mass that is needed to have lateral stability when it's a single wythe and usually a cavity wall.

We're talking about a small arch here. I was just wondering why they think it's necessary to anchor the arch...like if they have seen one fail before. Anyway, I don't want to make anymore if this. It's tied in, the builder is happy and that's all that matters. Don't mind me.....

[Gulf]

Re: Help with modular oven - decorative arch.

Stonecutter,
Go back to the op. The Face brick arch is "free standing". It is not tied in with any thing at the moment. There was noticable movement when cleaning. Tyng it in with the render seems like the most viable option to me .

Joe W.

[stonecutter]

Re: Help with modular oven - decorative arch.

I did see that.

[david s]

Re: Help with modular oven - decorative arch.

In my case, yes I did have one arch nearly topple forward and since then I always tie it back. You may notice a small piece of cardboard placed temporarily between my arch and the flue gallery to maintain small gap so the inner expanding parts of the oven don't create pressure on the outer decorative arch.I've built around 100 ovens this way, it seems to work and I've not had any cracked outer arches, a problem I often see in other ovens, so I will continue with this method. If you hadn't noticed the arch is cast in one piece rather than separate bricks. There is more than one way to skin a cat and certainly plenty of ways to build a WFO.

[stonecutter]

Re: Help with modular oven - decorative arch.

In my case, yes I did have one arch nearly topple forward and since then I always tie it back. You may notice a small piece of cardboard placed temporarily between my arch and the flue gallery to maintain small gap so the inner expanding parts of the oven don't create pressure on the outer decorative arch.I've built around 100 ovens this way, it seems to work and I've not had any cracked outer arches, a problem I often see in other ovens, so I will continue with this method. If you hadn't noticed the arch is cast in one piece rather than separate bricks. There is more than one way to skin a cat and certainly plenty of ways to build a WFO.

Thanks for answering my question...just one more. Did the arch nearly topple forward when you dropped your form or during use? Like I said twice, if it works did you that's good, I just like to know why. Btw, good idea to create a gap with the cardboard for expansion. See, that's why I want to know about why you tie it into the dome. And you'll get no argument from me about different ways of going about a build. I'm one of those people that doesn't care as much about the how, but more about the why.

[david s]

Re: Help with modular oven - decorative arch.

Thanks for answering my question...just one more. Did the arch nearly topple forward when you dropped your form or during use? Like I said twice, if it works did you that's good, I just like to know why. Btw, good idea to create a gap with the cardboard for expansion. See, that's why I want to know about why you tie it into the dome. And you'll get no argument from me about different ways of going about a build. I'm one of those people that doesn't care as much about the how, but more about the why.

In my case I don't set up a form on the oven, but cast the arch in one piece separately, then mortar it in position so it is perched on its base which leaves it a bit vulnerable until it's tied into the outer shell. Because it is thin this balancing act makes it more unstable than if it were thick.

[david s]

Re: Help with modular oven - decorative arch.

This pic probably illustrates better the problem of having an isolated arch until it's tied into the outer shell.

[stonecutter]

Re: Help with modular oven - decorative arch.

I think if I was making a cast arch like that I would change the bottom dimension, and flare it out about an inch.

[david s]

Re: Help with modular oven - decorative arch.

I think if I was making a cast arch like that I would change the bottom dimension, and flare it out about an inch.

That would improve the stability problem on placement a little, but I'd then lose the expansion gap at the base and it would make the mould more complicated,
I'm not about to alter my design, just posted the pic to explain the situation

[stonecutter]

Re: Help with modular oven - decorative arch.

To be clear, I'm not trying to reengineer your design...your happy with it and it works for you.

As far as flaring the base. The only thing that changes is the plane of the outer face on the arch, not the back...so you're not losing the expansion gap.