The weakest part of any granite countertop installation is the area of the granite right in front of the sink. Typically this area is only 3″ wide from front to back. To strengthen this piece many installers will cut a channel in the underside of the granite and install a steel rod for support. Though this adds support the steel rod can pose a problem down the line. If the adhesive used to secure the rod fails is starts to rust. When this happens the expansion and contraction of the metal causes a fracture in the granite. The first picture in this post is what that type of fracture can look like.
You wind up with a crack in the granite running parallel to the front edge and against the “grain” or natural pattern in the stone. When reviewing this with the customer that’s exactly what I thought this was. Rather than being in front of the sink as usual this was directly above the dishwasher. At the top of the door to the dishwasher directly beneath the break in the top was the exhaust vent. As the dishwasher ran through its cycle hot steam came out of the dishwasher and directly onto the bottom of the granite. When I looked beneath the granite I discovered that an anchoring mechanism for the dishwasher had been installed in the bottom of the stone. This mechanism was them glued in with a resin adhesive. The adhesive had failed and whatever the support screws were attached to was rusting and causing the granite to break.
I had the homeowner pull the dishwasher out so it would be easier to work in this area. I then went about cutting away the old adhesive. Once this was done I found something I didn’t expect. An 8″ long, 2″ wide piece of wood glued into the granite.
What was happening here was that when the steam exhaust left the vent on the door of the dishwasher is was going up through the screw hole used to anchor the machine. What happens when wood gets wet? Over time this wood was expanding causing stress on the granite and the crack seen in the first picture.
Do complete the repair properly we had to remove all pieces of the wood. Once we had all the pieces of the wood chipped out we glued the broken piece back on then filled the gap on the bottom of the stone with adhesive. Once this was done we fill the surface pits of the break then ground the repair flat. We then re-polished the affected area and unless you know what happened you can’t even tell a repair was done.
By Josh Huseby 8-8-2016