Granite hearth damaged by lack of floorboard expansion gap

[martinraba]

Hi - just wanted to share a couple of photos and get some opinions on whether my 48" x 15" granite hearth will need replacing due to crack damage. The hearth was installed along with a reclaimed Victorian fireplace three years ago.

As far as what happened... I've discovered that my contractor really dropped the ball when installing my living room floorboards in 2016. The boards are now cupping quite badly and after inspecting the perimeter in the only areas I can get to (ie hearth & meter cupboard) I can see that no expansion gap was left. I'm therefore pretty certain that my poor hearth buckled under the pressure of expanding floorboards.

My solution is obviously to get someone round to remove all the skirting etc & add proper expansion gaps around the whole room perimeter. Hopefully that will allow the cupped wood to settle down after a few seasons - and if not then it's become permanent so I can sand it away. But the damage to the hearth is another matter.

As things stand there's no movement or discernible weakness - it just cracked as shown under the pressure. After adding a gap will it be possible to patch up the cracks with something like this https://www.pureadhesion.co.uk/joll...filler-travertine-repair-kit-black-150ml.html ? Given the position of the cracks (both sides of both corners) I guess there's a chance that two corner pieces of granite will pull away once the pressure from the wood is relieved. If so, would that make the whole hearth structurally unsound? Or can I just keep the damaged bits in place, fill the gaps with resin & forget it ever happened?!

EDIT: added a pic of the fireplace pre-installation. NB that the floorboards shown there are now actually the subfloor - I had new solid wood boards laid perpendicularly on top.

 

[jetsam]

From what I can see, there are two slabs of granite, and only the bottom one cracked. Looks like it will be okay to me, but you should cut the flooring back at least 1/8" all the way around.

Honestly, if it was me, I would consider either cutting the flooring back a couple feet, or adding some tile or stone to the top of the flooring to give you some room in front of the stove to handle flying coals, rolling burning logs, etc.

 

[Highbeam]

A toe kick saw would be my chosen tool for creating the gap if you desire to do this. " I had new solid wood boards laid perpendicularly on top"

 

[begreen]

Not sure if the flooring is the issue. It could be a slight difference in levels between the original hearth base and the flooring. Or, was the new flooring run right over the original concrete hearth up to the fireplace face? If that is the case, it is all wrong. Wood does not belong under a fireplace hearth.

After you get all defects corrected I would try to repair with a black epoxy compound.

 

[jetsam]

I did 't consider that the granite might be ON the flooring given the title of the thread, but it kind of looks that way in the photos?

 

[begreen]

At this point I'm just asking in order to better understand the construction details here.