Cantilever Engineering

[Ken524]

Thanks everyone for the great discussion. In reference to Frank L Wright's "Fallingwater" house, did you see where his cantilever has been sagging for several years and was forecast to eventually collapse? Apparently, poor workmanship (not poor design) was blamed. Engineers were able to design a fix a couple of years back using a series of high tension cables. All is well at the Wright house now.

Paul, your code research helped quite a bit! My rebar is about 2" below the surface. 30mm is about 1.5 inches. So I'm good there. While U.S. code may differ from Aussie code, the laws of physics are identical on both of our continents!

Anyway, after wondering about this last night, I ran to the Depot this morning and grabbed 4 more pieces of rebar and added them in at the point of max tension. As I was finishing up, the concrete truck arrived so the rest is pretty moot!

Thanks Unofornaio and Dutch for the confirmation that I'm in safe water here.

I attached a pic of my extra (and likely unnecessary) rebar and the fresh pour.

Thanks again all!!
Ken

[Archena]

Originally Posted by Ken524

...

While U.S. code may differ from Aussie code, the laws of physics are identical on both of our continents!

...

Are not! Everything is upside down down there.

[Unofornaio]

Thats China....isnt it?

[Archena]

Nah, China's just the place you get to if you tunnel straight through the Earth. You have to take a right turn to get to the Southern Hemisphere where everything is upside down.


:teeth:

[Hendo]

Originally Posted by Ken524

Paul, your code research helped quite a bit! My rebar is about 2" below the surface. 30mm is about 1.5 inches. So I'm good there.

Pleasure – glad to help out. Always good to know you’re not getting too thin with the cover. As Uno has stated, it ain’t going to move – even without that additional rebar (but what price peace of mind, eh?).

Cheers, Paul.

[asudavew]

I spoke with my father last night.
He was a commercial carpenter for over 30 years.
Lots of concrete work, planning, forming, etc.

I asked about a cantilever.. (i couldn't remember the name, but he spouted out what it was called when I said concrete overhang.)
anyways...

He said a 12" over hang is no problem at all, he built one before that was 4 foot long and built out of 3 1/2 inch concrete. It was designed by an architect. Of course the slab was much bigger so the overhang could be larger, but he said I didn't even need rebar in the slab, mesh would work just fine, but I think I will use rebar just in case.

Anyways.. I have no fears about a shelf anymore

[Ken524]

Originally Posted by asudavew

He said a 12" over hang is no problem at all...
Anyways.. I have no fears about a shelf anymore

Thanks for adding to my piece of mind! Now that the curing is done, it looks like one very solid piece of concrete.

Keep us the good work on your oven, I'm enjoying watching your progress.

Ken

[asudavew]

Originally Posted by Ken524

Thanks for adding to my piece of mind! Now that the curing is done, it looks like one very solid piece of concrete.

Keep us the good work on your oven, I'm enjoying watching your progress.

Ken

You are welcome and thanks.
I was interested in building a cantilever too, so I think my hearth will look very similar to yours. Well hopefully!

I hope you don't mind.

[Ken524]

Originally Posted by asudavew

You are welcome and thanks.
I was interested in building a cantilever too, so I think my hearth will look very similar to yours. Well hopefully!

I hope you don't mind.

I don't mind a bit. Imitation is the sincerest form of flattery
I'm really happy with the way mine turned out.

Ken