Split in Granite

[akmitch]

Can expansion and contraction of plywood underlay (desert environment) cause a large granite slab to crack?

[akmitch]

This is my posted question. My Master cool runs 24/7 in summer. House was closed up while we were away for a few weeks. Came home to a split in countertop. Another developed about a month later. I feel it was caused by cooler...similar to door frames swelling during summer months while cooler being used. Isn't there an adhesive that would allow a little flex to compensate for the swelling of the wood so as to not stress the stone to the point it ruptures?

[Stone Dude]

we use silicone to bond to substrate for that reason. it could have contributed

[Mark D.]

Cameron,
correct me if I am wrong but since the wood expands and contracts at a greater rate than the stone, and since the stone is stronger than the wood shouldn't the substrate crack if either of these two are going to crack due to excessive expansion and contraction?

Mark

[Stone Dude]

theoretically no, because the stone is solid and doest really have any room to expand, so instead it cracks. you will probably never see a wood substrate crack because it does expand and contract, but the wood does deteriorate over time underneath floors and such. i did just diagnose a cracked granite island and the issue was that they used 2 pieces of wood, and the gap between the wood was right over the dishwasher. the heat, moisture, and the seam in the wood all contributed. also, when exposed to excessive moisture, wood will swell and expand to a point where it could cause a crack if the stone has no room to move.


if the stone was set with epoxy instead of something expandable like silicone, it is a possibility that this couldve been a contribution.

[Mark D.]

Thanks.
I sent you an email regarding polishing pads.

Mark

[akmitch]

Cameron,

Thanks for the information. This will be very helpful when I talk with the installer next week. He is pretty "ticked" about having to replace the granite slab. He is in total denial that such a cause is even possible. He works out of So. Cal and has been in the business for quite a while and this (he claims) is his first experience with a fractured stone due to expansion. Evidentally, he only uses an epoxy in his installs and has never used a silicone type mastic. The business owner has bucked up for the job and is having the installer use a different mastic (one with with some flex) this time around. The installer is ticked about that too. He seems to be set in his ways and is afraid to learn anything new.  Anyway, thanks again!     

Al

P.S. Good forum...I'm sure I'll learn a lot here

[Stone Dude]

it may very well be his first time with a problem, but he could also have quite a few popping up everywhere if yours is the first. we just use the normal silicone in a caulking gun with shims to level it. its a countertop, why would you need epoxy? im certain you dont dance on your countertop, and if you did, silicone would be just fine. thats a good thing that the company is stepping up to make the repair though, not a lot of companies these days stand by their work.