How can we safely remove a granite fireplace hearth glued to the subfloor without damaging the gas insert, without resorting to cutting the floor?
Asked by Jerzy Gellert 
6 months ago
Last Updated: June 21, 2024
So we’ve got this granite fireplace hearth that’s basically glued to the floor like it’s never coming off. We’re a little hesitant to start swinging a sledgehammer near the gas insert, so any advice on how to tackle this without causing a disaster? Is chiseling the way to go, or are there any other tricks we should know about? Thanks in advance for any help!
Using a rotary hammer could speed up the process
Bring out the heat gun
That granite is staying put! *gives granite a little tap*
‘t forget about the air chisel
Just make sure to patch up any chips in the subfloor if it happens when taking it out
I can’t stop laughing, it’s like they were trying to see how much glue they could use 😂😂☠️
Lean some cardboard or Masonite against the fireplace and opt for a larger hammer.
It might be simpler to cut it out and replace just that section of the subfloor.
Consider purchasing a heat gun for around $20 to help melt the glue securing the stone in place. I attempted using a hair dryer in my kitchen but quickly realized a heat gun was necessary. It’s definitely a worthwhile investment.
Isn’t effective with every type of glue. It may not work depending on the specific glue used.
I’m on the same page as – a rotary hammer drill from Lowe’s should get the job done. Bosch is currently on sale for $199.00 and can have it removed in just 10 minutes. Today I managed to dig through 12” of solid concrete with one.
You could rent a mini jackhammer tool to help with that – it’s like a combo drill & jackhammer.
Prefers using an SDS hammer drill
Absolutely! I actually took out old concrete near a fireplace by drilling holes in the slab and then carefully hammering in between. Managed to remove chunks without putting too much pressure on the stone fireplace.
Cut around the subfloor near the granite, then lift and replace it.
I think using a rotary hammer is a good idea, or if you’re looking for a more budget-friendly option, a multi-tool could work as well. There are plenty of attachments available that could be helpful.
If you have a chipper that’s great, but if not, some elbow grease will do the trick. It shouldn’t take too long, but make sure to have a 2 lb mallet handy. You might also want to place a piece of plywood or drywall in front of the fireplace and remember to turn off the pilot and gas first. Haha
You might end up causing some damage to the subfloor while trying to remove it. The easiest option would be to cut around the subfloor, remove the entire piece, and then replace it.
Try grabbing a multi tool to cut through the glue first, then break the granite bit by bit.
I might attempt to chip that away, however, I wouldn’t be shocked if eventually removing the subfloor and replacing it with a new piece turns out to be the most effective solution.
Consider using an oscillating multi-tool or at least getting a 3lb sledge. A full sledge might be overkill, but a one-handed hammer can also be helpful.
Did a great job using the oscillating tool to flush the floor around the edge. Breaking off the edge and repeating the process. Slowly make your way in.
Using an angle grinder with a diamond blade or a wet saw could do the trick.
Using a multi tool will take ages. Just keep doing what you’re doing. You might have to replace the subfloor once you’re finished. Try using a 3lb hammer
Totally! You don’t have to switch to a 5lb sledgehammer, but that tiny ball peen hammer will definitely slow you down.
Try using some karate moves.
‘t forget your safety glasses, no matter what you decide to do.
If it’s not possible to cut the subfloor under it and replace it with a new piece, the next best option would be using a bigger hammer block insert and getting to smashing. Less mess and headache that way.
Maybe a 6-foot pinch bar could be more effective, or even a pry bar.
You could try using a heat gun along with a mud knife.
You might need to replace or even out the subfloor. Just use any tool you have on hand, like a circular saw, a cut-off tool, a multi-tool, etc.
Hammer drill using a chisel attachment
I had a similar situation and I took my time using a crowbar and hammer to chip away tiny pieces. It felt like it took forever.
Chipping hammer all day every single day
Try heating the granite slab with a heat gun to soften the glue before prying it off. If that doesn’t work, consider renting a Hilti or air hammer from Home Depot for a few hours.
Using a hammer drill with a flat paddle bit can cause some vibrations.
Just cut out the subfloor and replace it – much simpler that way.
Yeah, it’s definitely time for a replacement with it starting to de-laminate like that.
Is the champion!!!! I totally agree
Remove the subfloor by cutting it.
The only way I was able to remove glue from my front porch carpet left by the previous owner was with a Heat gun! It took a lot of time though. It seems like cutting it out might be easier.
All you really need is a hammer drill
How about giving an adult-sized hammer a shot?
Try using a larger pry bar.
Hit it from below and lift it out.
You could also try using a chipping hammer. Do you have an SDS hammer drill with a hammer option by any chance?
Small hammer and crowbar.
Why are you using a metal ball peen hammer for this demolition? Maybe try a mallet or claw hammer instead.
I’m just curious, , why do you think a ball peen hammer is better than a claw hammer?
From a physics perspective, a mallet would actually be the best choice for this situation.
Could use the claw to pry things up. Personally, I would go with a mallet first.
The ball peen hammer is great for hitting cold chisels, while claw hammers may not have the right strength and could cause chipping. However, a claw hammer is handy for prying.
Why though? 🤦♂️
Consider using a pry bar and hammer, and covering the fireplace with plywood to protect it during work.
Use a heat gun to remove the stubborn glue. I just dealt with this.
Cover the fireplace with drywall or plywood and start sledgehammering!
Remove the glass insert, please!
I’m moving on after cutting that floor.
When using a heat gun and practicing patience, cutting out the subfloor will lead to additional work.
When you heat it up with a heat gun, the glue will let go easily.
Air hammer