Is this plan (oven entry) structuraly strong enough ?

[nachtwacht]

Re: Is this plan (oven entry) structuraly strong enough ?

Thanks ATK406. I think I will indeed do exactly that. It sound to me like "fairly easy" to do and structuraly very strong.

[ATK406]

Re: Is this plan (oven entry) structuraly strong enough ?

Option 5 sounds like a winner if you are dead set against buttressing the arch from the outside. But I would fill the hole in your "stones" and slab (surrounding the rebar) with cement (mortar) to ensure the rebar is anchored to the slab and enusre that there is no movement between the rebar and the "stones". I would use 1/2" or 5/8" rebar for this.

[nachtwacht]

Re: Is this plan (oven entry) structuraly strong enough ?

Mine should be finished before that so if it has imploded, please don't tell me

Thanks for all the advice !

[stonecutter]

Re: Is this plan (oven entry) structuraly strong enough ?

......... but it is reassuring that your oven is still standing without it .......

I haven't seen the oven in over 3 years, but we are heading up to CT in Oct, and I planned on stopping by to check it out. Hopefully the dome hasn't imploded and the arch a crumbled ruin.

[nachtwacht]

Re: Is this plan (oven entry) structuraly strong enough ?

You can see in this pic that the vent is just butted up to the oven opening.

That is exactly what I was planning to do ! I had found your picture and stored it localy allready and it is basicaly where I got the idea from I just did not know where it came from anymore.

And you made that without any cladding ? Nice...

I think I will use cladding or some other extra reinforcement anyway, just to be sure, but it is reassuring that your oven is still standing without it I do have the feeling that in your door the arch is a little more bend and the the 3 stones that it is standing on are a little lower (for sure, since I use 4 stones) That will structuraly probably make it somewhat stronger... I will see if I can live with a small redesign like that. I will still use some reinforcement but it will only be half way the stones so I like to make it as strong as possible without the reinforcement...

Again thanks for all your replies.

[stonecutter]

Re: Is this plan (oven entry) structuraly strong enough ?

ok. You confirmed one of my other things I feared. Vermicrete is probably not good under compression. The rebar will make the vermicrete crack over time and then the rebar is useless, both around the dome and next to the entry arch.

Vcrete is pretty good under compression, and the more portland in the ratio, the higher the compression rating. The problem, as with regular concrete and most masonry, it has weak tensile strength. That is way reinforcement is added to concrete or cladding....it's just that vcrete/perlcrete is weaker in bind strength as well, compared to concrete or mortar.

[stonecutter]

Re: Is this plan (oven entry) structuraly strong enough ?

You can see in this pic that the vent is just butted up to the oven opening.



If my arch failed, no mortar joint between the twp arches would be enough to prevent it. In a sense, because the two arches are independent, that is a control joint.

[stonecutter]

Re: Is this plan (oven entry) structuraly strong enough ?

Very nice one. I plan to do the same indeed with the first "inside" arch exactly like you did there.

However, the arch I am in trouble with, will be in front of it and I do not want to have them "touching". (there will be a small thermal break between the two)

The vent arch was touching on that oven, but contact with the oven arch does not have any structural properties at all, because it was not tied into the masonry behind it. So, it doesn't matter if the oven opening arch and the vent wall arch are butted together or not.

My current oven has two thermal breaks. I don't know how effective they are during live fire cooking, but I do see a benefit for baking and longer heat retention. I hadn't incorporated one before, so that's why I did it on this oven.

[nachtwacht]

Re: Is this plan (oven entry) structuraly strong enough ?

Sorry to clutter up your thread, but I found another image. I didn't buttress the vent wall, I had forgotten about that. No problems there either.

Nice! Basicaly that is very close to my idea. You do have it connecting to the oven wich will give it some extra support, but I can also get that little bit of extra support. To me it shows that there is some merrit in the idea that I have.... It will need extra support and can not be free standing, thats clear to me now but I can use the arch that I have in mind...

nice. Now just have to deside how far back it has to go into the oven because while talking to you and looking at my models, I suddenly realised, like in the last picture you have send, it has to go further into the oven else it would not look nice and round anymore. Next oven I should build from clay. If I don't like it, I make it wet and start over gain

[nachtwacht]

Re: Is this plan (oven entry) structuraly strong enough ?

I built an oven arch like that on my other personal WFO.

Very nice one. I plan to do the same indeed with the first "inside" arch exactly like you did there.

However, the arch I am in trouble with, will be in front of it and I do not want to have them "touching". (there will be a small thermal break between the two)

Because it is free standing I do not know (yet) if I can get any kind of reinforcement from the oven side... I have to get it from the concrete slab or butress or cladding I think...

Thanks for all your input by the way, apreciated !

[stonecutter]

Re: Is this plan (oven entry) structuraly strong enough ?

Sorry to clutter up your thread, but I found another image. I didn't buttress the vent wall, I had forgotten about that. No problems there either.



Am I telling you not to buttress your arch? Nope..it's good insurance.

[nachtwacht]

Re: Is this plan (oven entry) structuraly strong enough ?

As mentioned, rebar wont do anything in Vcrete. You could try a couple layers of wire mesh, but I still think the tension will brake up the insulation. But it will be encased with stucco too, so this may be over thinking a bit.

ok. You confirmed one of my other things I feared. Vermicrete is probably not good under compression. The rebar will make the vermicrete crack over time and then the rebar is useless, both around the dome and next to the entry arch.

So it has to be either a steel wire wich is put tightly against the stones or wire mech (as in chicken wire right ?) and 1 inch of concrete around the dome.

However, since the entry arch will be showing about half (the other half will be in the stucco / insulation) I have to come up with a good way of reinforcing that...

Anyone ever tried to drill a hole in the concrete slab, put rebar in there, and then also drill a hole in the first 4 stones in my picture ? I don't see them falling then anymore and I would that it is a fairly easy solution. Since I plan to incorportate a thermal break the entry arch should not get to hot and no heat should go into the concrete slab....

I should probably file the above as "Option 5"

[stonecutter]

Re: Is this plan (oven entry) structuraly strong enough ?

Back to the entry arch... yes, I have considered other designs including those that are self supporting. It's just that I like this design better than the others. So if it will be to complicated / definatly not strong enough, I can do something else.

since a picture usualy says more than a thousand words, this is basicaly what I had in mind for option 3) It is a top view and the vermicrete goes all the way round the oven to the other entry arch.

And yes, it will be a SS double walled pipe so that will not be to heavy....

I built an oven arch like that on my other personal WFO. Besides this one and a pre-cast, all the other ovens I have built, including restoration of historical beehive ovens, have had semi circular or equilateral arches.

The solution I came up with for my CT home oven was to set back the sides of my oven opening. Compression from the dome acted like a buttress on the sides of the arch, so the lateral pressure from the walls of my opening were contained. I used no cladding on that oven....I parged the outside of the dome and it was surrounded by insulation batts and loose vermiculite.

Here is a picture of the opening....


You lose a bit of space doing it that way, but I didn't find it to be a negative at all, because you don't usually cook within the first few inches of the opening anyway. I just didn't want the extra work of building a buttress or have to encapsulate the arch with reinforcement. The only reason I used reinforced cladding on my current oven is because it is a low dome (Neo) with soldiers.

Further, my arch carried 3 full lengths of 8"x8" clay flue and a small fire brick 'smoke shelve'.

[stonecutter]

Re: Is this plan (oven entry) structuraly strong enough ?

Intresting thread since it is almost the same as I have in mind to be building. What did you use there for cladding ? It is a thin layer. Does not look like you have put any rebar into it. I was thinking about using steel bracing myself around the oven like Tscarborough did wich he shows here here

Tscarborough still used concrete around it. I however wanted to use vermicrete since I did not want to add more mass to my oven. (I can live with 1 inch like you used though....)

I used wire fencing as reinforcement...one layer wrapping the soldiers horizontally, then another that covered the dome, extending over the soldiers. The cladding layer was around 1" thick, with sand being the only aggregate.

As mentioned, rebar wont do anything in Vcrete. You could try a couple layers of wire mesh, but I still think the tension will brake up the insulation. But it will be encased with stucco too, so this may be over thinking a bit.

[nachtwacht]

Re: Is this plan (oven entry) structuraly strong enough ?

I didn't document the process on my thread, but I applied 1" RC to my dome, which is a Neapolitan. Shortly after it was cured, I stood on top of it, just for haha's when I was framing the enclosure.

I do think a layer of v-crete or perlcrete would work, but I feeling it would have to be more than 3"...closer to 6". I will say that I have no data or past experience with this theory, just structural masonry intuition.

Intresting thread since it is almost the same as I have in mind to be building. What did you use there for cladding ? It is a thin layer. Does not look like you have put any rebar into it. I was thinking about using steel bracing myself around the oven like Tscarborough did wich he shows here here

Tscarborough still used concrete around it. I however wanted to use vermicrete since I did not want to add more mass to my oven. (I can live with 1 inch like you used though....)

Back to the entry arch... yes, I have considered other designs including those that are self supporting. It's just that I like this design better than the others. So if it will be to complicated / definatly not strong enough, I can do something else.

since a picture usualy says more than a thousand words, this is basicaly what I had in mind for option 3) It is a top view and the vermicrete goes all the way round the oven to the other entry arch.

And yes, it will be a SS double walled pipe so that will not be to heavy....