Replies

1. 
   Guest_ | Oct 24, 1999 12:49am | #1

   *
   Isaac,

   What you are looking for is the modulus of rupture rating for the stone. This in simple terms is a bend test. Stone does have a certain elasticity.

   I would not trust a 300# person placing himself on any cantilevered granite top (Island with significant overhang)let alone 3/4" (2 cm.). Most slabs are also available in 3 cm. May be a safer bet along with providing a full deck beneath the stone.

   Let me know which stone it is (MIA name) and I can tell you the modulus of rupture from the MIA manual. For comparison between a wide variety of stones, most stone fabricators should have this publication.

1. 
   Guest_ | Oct 24, 1999 05:42am | #2

   *Jim is right about the properties of the stone you want to know. You can find it throughout the 'net using as key search words. Also, look under the Tile Council of America webpage. This came up the other day: seems this one slab installer likes to use thinset as an adhesive. He also spots it on the slab instead of going for 100% coverage. Well, I get alot of repairs from his work because the stone does indeed crack when the span is too great between the spots or, over time, the stone sags enough to exceed its elasticity.So, given that a slab will bend enough to crack where the span is measured in inches, I'd say you'll experience failure quite soon if you attempt to span a considerable distance without any support. Stone slabs are not known for their high tensile strength.BTW: I remember seeing a picture in one of my geology texts showing a marble--sure, different stone, but stone nonetheless--benchseat which had sagged over its 80 years quite noticeably, even though it was 4" thick.

1. 
   Guest_ | Oct 25, 1999 05:17am | #3

   *while your checking with the manufactorers/fabrcators you might want to check on whether they can put steel into the stone. We have had renforcement epoxied into the slab when we were concerned about peice breaking. I do not do a lot of this work but knock on wood no call backs on the dozenor so pieces we have set over the past five years.Granite seems to be pretty forgiving I would be more worried about marble or limestone.regards Kevin

1. 
   Guest_ | Oct 25, 1999 10:09am | #4

   *The fabricators I deal with would never put steel in the slabs; I mean, they wouldn't want to expose themselves to that liability. Steel expansion would cause cracking of the slab. I suppose you could get around this by cutting a larger channel for the steel and encasing the whole thing in epoxy.For that amount of work, why not go the safer route of epoxy embedded mesh?

1. 
   Guest_ | Oct 25, 1999 10:59am | #5

   *Rich,I think that what kevin was speaking of may be brass or nickel rod reinforcement. I have used this type of reinforcement in what I would consider "rotten of severely matrixed(stratified) stone. Especially those stones which are yellow, Taiwan Verde, Rojo Allicante or any soft stone cut on the bias. I have been unfortunate enough to have to deal with slabs(in a "past life") that would actually fall apart from the moisture presented to them from the cutting, grinding, profiling, honing and polishing operation.I learned from those lessons. If in doubt: look at the matrix, rod, Akemi and fiberglass the backside of the slab BEFORE cutting.It is ironic that some of the most beautiful stones in the world such as those from China, Taiwan, Turkey,Rainbow Onyx, Lapis($300 sf raw), etc. are considered "junk" simply because they disintegrate under the unnaturally wet conditions and vibration of fabrication.Steel? Only stainless and only for anchors in slabs on the vertical and for adjusting large dimension pieces into position. Too tough on the blades for anything else. And might I say, anything that would "rust" would bleed thru the surface. No poultice would remove that stain.And another thing: Don't spit your Copenhagen in your mud or setting bed while setting Thassos White or any light colored marble. It will eventually bleed thru as well. [grin]Jeff PS: Try ice blocks(chew can size pucks) for positioning those large granite countertops. Makes them very easy to fine tune for Akemi'ing the joints tight. Just make sure you clean the snuff out of them cans thoroughly before you put them in the icebox.[I sheepishly grin again]

2. 
   Guest_ | Oct 26, 1999 05:19am | #6

   *Jim, reading that last post makes me think that if we ever worked together, we'd have a ball, er, blast! Don't know why, but people look at me funny when I use the mud bucket as my spittoon. Some people!

3. 
   Guest_ | Oct 26, 1999 08:14am | #8

   *Yes Rich. The picture is clear in my mind's eye:2 five gallon admix buckets, a twelve pack of Rolling Rock and the grunts doing all the work.Should we clean those tools this afternoon Rich?Nah, we'll just have the grunts come in early tomorrow morning. [g]Regards,Jeff

2. 
   isaac_hankins | Oct 26, 1999 08:14am | #7

   *
   Any one know where to find the strength of granite
   I have a customer who is putting solid granite counter tops on cabinets (3/4") and the installers have advised him not to put a sub structer on top of the cabs.I have no problem with this however he Is convienced that if he sits on the counter he will break it.(6'6" 300#)If I can find something on this it will make a small but irratating problem go away. Thanks