Torch-Cutting a Granite Countertop

It's possible to trim the edge of a granite slab by applying heat from a propane torch. February 8, 2008

I am trying to install a cabinet that butts up against a fireplace that is made of split granite stone. The fireplace side is half block and half rock, the cabinet is against the block and the rock protrudes out from the block in front of the cabinet.

On the other end of the cabinet there is a 12" square post. I built the cabinet so I could angle it in past the rock, but have discovered the face frame hits the rock in about 4 places that stick out when I try to slide it in.

I would like to take off the high spots in order to get the cabinet in. The high spots range from .5" to .75". I have tried a cold chisel, but it takes too long and leaves tool marks. I could trim the cabinet but would rather not go there.

I have heard that it is possible to heat granite up with a propane torch and the expanding crystals will make the granite flake off. Does anyone here have experience doing this?

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor D:
Is grinding a possibility?

From contributor S:
Diamond wheel on a 4" grinder if the score/cut marks will not be visible after the install. All safety to be considered and followed. I don't know that straight propane would do the trick if you wanted to play with fire, but I would think that a setup that added oxygen would do the trick. They carved mountains with kerosene and O2 and iron powder torches can cut over ten feet of concrete... Okay, maybe a little bit of overkill.

From the original questioner:
The stone will be visible, so grinding is not possible. The use of a stronger torch is scary to me. I don't want to take off too much material.

From contributor D:
Sounds like it'd be easier to work on the wood instead of the stone. Maybe a little better planning next time?

From the original questioner:
I decided to go for it and everything came out fine. If you hold the torch on a single spot for about 1 - 2 minutes, the granite flakes (and pops) off very nicely in about .125" thick by 1.5" diameter pieces. I moved around a lot in order to minimize the amount of heat the rock was getting.

From contributor R:
And it didn't need polishing?

From the original questioner:
The granite was naturally split, so the pieces that I took off match the rest of the stone perfectly.