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Knows less all the time
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very nice as your usual. Thanks for posting.

Can you post some pictures from inside of the roof?

What was the overlap / overhang on each course both in cm and in % of the stone.
 

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mason contractors
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No, it's mortared. It is a corbeled vault though, which is a first.
Bill it's nice,. but to have a supporting vehicle [arch/dome] it needs to be wedging into a non-moveable, or an opposing side.
Judging by the pic this is not wedged in any direction
The flat thin stones are certainly laid circular and lapped but due to not being lock wedeged and soley dependant on a perminent bond, it is really short lived.
Even if you were to have pitched the stones ["they look nearly flat"] they are too thin to have any side "lateral wedge strength".
Would you corbel opposing circular 8'' granite steps to meet each other at the top and call it safe? I.E. what stops donward collaps of any section if laid flat?
If it was big it would fall in upon itself as nothing is stoping it but bond..ouch.
Pehaps it's the reason it's a 1st...... This same as laying masonry onto the flue and chamber soaps which you posted on the other page... no?

IE. if you could lay this well roof completely dry then I'm wrong....and it surley would be a "mirical of passion" as well as a first.

I could be mistaken if you built a dome correctly beneath it,. but what about shedding water i.e. the stones laid flat on a roof ?

Kudos for massive effort and raw talent but gotta listen to those ''Wise Men" :blink::thumbup:

Sorry for not cheer leading..my son hates me for it!
 

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Discussion Starter · #10 ·
Francis, I don't mind the criticism, but it is not warranted this time. Corbeled vaults are actually traditional. One very famous example is the Galloway oratory, an early Irish church that also happens to be dry laid.

My little building does not really compare, but there is almost four tons of stone in the roof. I think it would have collapsed during construction if it was going to.
 

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Vendor
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Definitely cool, but I think a little pitch would have been warranted in the roof coursing as well, and the first course as an overhang would give it nice shadow lines.

All constructive criticism, because it is very cool both in execution and because you actually did it.
 

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Knows less all the time
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Bill was it critical that the intrados touch? I assume that is what locks them in when a circle is completed and also load from above.

Being a builder of vaults and domes this intrigues me.

So they are not a dome but a vault? Would it work for a rectangular corbeled vault without loading above it like you would in a wall?

I have been trying to wrap my head around how the forces work. But then I am slow.

Francis don't hold your breath, corbeled vaults have lasted milleniums.
 

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mason contractors
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Francis, I don't mind the criticism, but it is not warranted this time. Corbeled vaults are actually traditional. One very famous example is the Galloway oratory, an early Irish church that also happens to be dry laid.

My little building does not really compare, but there is almost four tons of stone in the roof. I think it would have collapsed during construction if it was going to.
The Galloway I found is only 10' wide and was lime mortared. It has 3' thick walls and when you add the two walls it deducts 6' from the span.Yes they lable it a corbelled valt but when looking at the walls they are really practically built like two leaning stone walls, especially the exterior. and very steep! When those two leaning 36'' walls [or so called corbelled walls ] meet at the middel of the 10ft.building 1/3 of of eadc 36'' wall is actually plumb over the spring point.

All that I read srtesses that thes type arches are not for spans to boast about......and they all stress large walls to counter act the corbel and bolster the side walls.
There are those corbelled vaults which are nothing more than large stones stepped in with a cap stone atop; there are the leaning type such as the building you specified ,.quite steep and laid with the stones pitched somewhat to shed water;and there are false corbells which are made with large flat corbelled stone and covered over with thin stones in a shingle like fashion.
Now if you are doing a circular vault the span and and roof pitch are key ans common sense would depict. They span is the mid point minus the wall thicknessand I don't remeber you mentioning it nor has anyone asked,.. before they cheerlead.
As it appears by looking at your roof it isn't very thick and the stones are very flat. It is suggested practice that you incline the stones so they not only shed water but form a circular arch and lock tight with gravity! To lay in this pitched circular fashion and acheive a wedged
circlular course on each course they need some thickness or they simply will buckle and miss meet i.e. like laying slate.
To lay such thin stones so flat with no counter weight [width of the corbelled roof stone] you are basically building a flat frizbee which can have a tin can effect, had it not been for the cement.

What is the span and how thick is the roof,.. and is it a dummy?

This is what any intelligent person would ask......Fundi you started asking about lap which was a start....but you dropped the ball with what is important.

Bill you are very polite and talented.......I can see what your doing and it's not a walk in the park with masonry...stone work is very trying and just when you think you have it licked it bites you in the butt....I used to go to disco's with nearly ten fingers taped....stop on the way home at 3 in the morning and joint off the stone work!
never did like gloves..

I'm sure your roof is bonded well enough ....tell me though why didn't you use a thicker stone.
Alot of the corbelled vaults use large cap stones....think about it...the perimeter of the large cap stone lays over the lighter ends of the inner corbels which have 1/3 of their tail ends nearly PLUMB OVER THE SPRING POINT "timeless teeterless". i.e the dummy thin stones over it can hide it all if need be. strength then beauty?
 

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I don't think so. The ring can't sag since the stones on each side prevent the one in the middle from going anywhere and the stones below prevent the whole thing from falling.


Each stone is in compression from the stones beside it and since it's a ring there are no end stones. That's how I see it anyway
 

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Discussion Starter · #16 ·
The outside diameter is 8', wall thickness is 14", so an inside diameter of 5'8". The corbeled roof averages 16" in thickness with most stones being the full thickness.

I used the thin stones for two reasons. One, it's a material that is easy enough to work to the needed shapes. I think most people have heard of Tennessee craborchard.

Secondly, since it is so thin, it gives the illusion of a smooth cone without cutting angles into each course.

I don't have a picture from below, but it looks like the first one on JSR's site, but a bit rougher.
 

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Renaissance Man
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It's seriously beautiful to look at with Artisans skill being quite apparent. And, at that scale and pitch, I do believe it will hold up much longer than most of us will. But, I do agree with Disco Francis that in a much larger scale and lower slope, this design is a recipe for disaster if an underlying structural dome/cone or other means of support are not in place.

On a side note, I may have absolutely no idea what I'm talking about :laughing:

And Francis, please don't tell me you still got your bell bottoms :lol:
 

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mason contractors
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re;artisanstone Oh yeah I forgot. The roof stones are pitched outward a little bit. A quarter bubble on the level which is what we do with flagstone. That's to shed water, but 16" of mortar and stone should help too.

Bill you pitched it then they can't settle forward as it actually locks.
The thin rocks are best being cemented as I'm sure the edges aren't all square to lock against each other if they were butted tight.

just imagine all theose little trangular spots under ther to parge if it was a throat!..lol

I must say you know how to handle cranky old masons!
i.e. people skills ;)

Today I drove by a old job I did in around 89 or so. It is a big stone house built during the depression which my grandfather worked on as a stone mason. I remember my father doing plaster patches there and as a kid I had to bring the supplies in and hand him the plaster on cedar shingles onto his hawk.
It was winter and I brought in a plastic tarp onto the kitchen floor,.. a peice of ice fell off and started to melt. The woman started to sceem bloody murder and had me remove it...scared the heck out of me,.. as a kid.
Years later [she had passed away ]I had to rebuild the two chimneys which leaked badly.
I think they are making it into a museum now that the Lawyer and Derby Icon, Harold Yudkin has also passed away. It has the most beautifull cork floors that I've ever seen. Top floor walls are 24'' thick.
 

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Bill you pitched it then they can't settle forward as it actually locks.
The thin rocks are best being cemented as I'm sure the edges aren't all square to lock against each other if they were butted tight.
The stones wouldn't need to be tight to lock without mortar, just have 2 points on each edge touching so it's more than just a pivot. Mortar is better in the short term (the next 70 years or so in his climate)

I think the pitch is just to shed water. I could be wrong
 
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