Setting a Bluestone Slab Hearth

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DustyRoads85

New Member
Nov 24, 2021
4
Pennsylvania
As the final part of renovating my Living room, I chose to update my fire place, removing the dated mantel & the redish/orange ceramic tile in the hearth. To replace the hearth, I templated the opening & had a 1.5" thick bluestone cut.

The stone will need to be set down into this opening. The top of the stone will be flush with the bottom of the fire brick & the hardwood floors. I offset my template 1/8" on all 4 sides for clearance.

My issue here is that this stone is not easy to move. Its definitely a 2 man job, exceeding 220lbs & roughly 20" X 70". I'm worried that when I place my mortar & screetch it, when I set the stone it'll be too high & I'll be unable to set maneuver the stone low enough to get flush with the floors & fireplace. or perhaps the opposite - when I set the stone it'll be too low & pulling it will be a real messy process.

I'm considering using straps to pick up the stone and set it in the opening, getting it to where I want & then just pulling out the strap. But that doesn't solve my concerns with getting the stone flush.

Any insight would be greatly appreciated. Photos of the fireplace & stone for reference. Thanks!

Fire_Place.jpg Blue_Stone_Slab.jpg
 

RandyBoBandy

Minister of Fire
Feb 25, 2015
1,353
Whitmore lake, MI
The piece looks to be thermal finished which means it’s probably very straight and uniform. If it can be dry set with out any rocking you should be fine. You can use a 6’ level to span the opening and measure down with a tape to make sure you have your 1.5” everywhere for it to sit flush. Ideally you base would be 1-3/4” so you could float it in 1/4” mud. There’s a tool out there called the Grabo. It’s basically a vacuum powered suction cup. Works great on smooth surfaces. However it’s something like $250.00 per unit. So I’m guessing you don’t want to spend that for a onetime use.
 
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RandyBoBandy

Minister of Fire
Feb 25, 2015
1,353
Whitmore lake, MI
Grabo Electric Vacuum Suction Cup Lifter Max. Load 375lbs for Lifting Wood Marble Granite Glass Tile Concrete 1 Battery with Carrying Bag Amazon product
 

RandyBoBandy

Minister of Fire
Feb 25, 2015
1,353
Whitmore lake, MI
Ideally you would want two of these for your application. Maybe you can buy two and resell them on eBay or try and sell them to your local equipment rental company. Or see if they already have them that you can rent.
 

DustyRoads85

New Member
Nov 24, 2021
4
Pennsylvania
Randy,

Yes, it’s a thermal cut stone and pretty consistent in its dimensions.

Setting it dry - sand or mortar did cross my mind.

If I did that I guess there would still be no issues with grouting between the fireplace and the hearth.

As you mentioned, ideally yes I’d build up my hole to 1 3/4 and then drop it in to 1/4” of mud. I think a thin application of mortar like that I should be able to maneuver it flush.
 

all night moe

Burning Hunk
Nov 19, 2015
215
earth
Nice piece of bluestone. I put my stove on a hearth pad I built this fall. The stove is sitting on top of some cement board.
For next season I'm hoping to do bluestone on top of the cement board, dry fitted as well. So many projects here and tasks to accomplish.
My vote is for dry fitting as well.
 

DustyRoads85

New Member
Nov 24, 2021
4
Pennsylvania
Well, I went for it yesterday and put it in.

I broke it into two pours. I first created a screet that set my mortar about 1 5/8” - 1 3/4” below my finished floor. I let that set up over night.

Following day I used the same S type and 1/4” troweled it down. My floor isn’t perfect so I had to build some areas more than others.

I liberally wetted the back of the stone and sat it in. I needed some minor adjustments so i pulled it, tweaked the bed and reset it.

As I said the floor isn’t perfect but I was able to get some movement out of the stone and got it set about as good as I could expect. I left about a 1” gap around the perimeter where I didn’t apply mortar so I could assure I’m the mortar wouldn’t squeeze up around the edge and make it difficult for me to wiggle back and forth to get the stone to the level I needed.

Also, I used ratchet straps to lift and set it. Specifically these were the cheap harbor freight straps that were thin. When the stone was set I removed the ratchet and slipped the strap out. This worked perfect.

It looks good and I thank you folks for the advice!

A42ECCA7-2F72-42B7-9255-9CE7EC4EB5A7.jpeg
 

all night moe

Burning Hunk
Nov 19, 2015
215
earth
Nice job, and It looks great!!! I love the hue of bluestone and had my hearth built in my mind for some time. I saved your pic to share with my wife. It's hard for her to visualize something unless she has something to see. Your example is key for me. I'm piecing thoughts and ideas together as the remodeling of this farmhouse slowly continues.
 

DustyRoads85

New Member
Nov 24, 2021
4
Pennsylvania
196F7364-9C45-4F98-B8EC-E75F688CF857.jpeg
Well I am almost finished with the project. Added a surround I built with a solid cherry mantle. My wife did the schmear as neither of us were fans of the dated brick.

I filled the gap between the blue stone and the fire brick with mortar but I’m not sure what I should use to fill the gap between the hard wood floors and the stone.

My biggest concern here is staining the stone. I bought some premixed grey grout but again I’m worried about staining. Is there a caulk that could be used here which could take some heat? The gap is about 3/16”

Thanks in advance for any suggestions.
4FE9001A-7A63-407B-943B-7EFF44CEEBF6.jpeg
 
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