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dm1337 06-11-2012 10:59 AM

Replace mortar between stones in fireplace hearth support

My brick fireplace hearth is supported by large stones sticking out perpendicularly to my foundation wall in the basement. It forms a kind of shelf on top of which the hearth was laid. The stones themselves were attached together and to the foundation wall using mortar. This mortar was very crumbly and falling apart. I removed all the old mortar therefore the hearth is not supported by the stones anymore. I'm looking at replacing the old mortar and providing structural support to the hearth again. I was advised by a mason to inject new mortar above and between the stones using a mortar bag from below. He advised me to use type S mortar for this.

I already have a 60lb bag of Quikrete FastSet Repair Mortar. Is it wise to use this product in place of regular mortar, or should I really use mortar? The FastSet seems to be a structural solution so I don't see why it couldn't be used in this situation, but it's only advertised for concrete repairs, so I don't know.

Thank you.

TRUEPRO 06-12-2012 04:18 PM

Try the quickcrete first. You really dont need a fast setting product because time isnt of the essence. I am worried about the fast setting quickcrete brand getting hard inside the grout bag that you need to use. Make a little bit up in a small pale and see how long it takes to harden.Test and tune a lil and go from there. Overall not a difficult project at all you will have good success.


dm1337 06-14-2012 12:27 PM

Ok, thanks, I will use type S between the stones because the fastset takes literally less than 20 minutes to harden and this will be hard to work with a bag. Also it cures to 6000 psi which is probably a lot stronger than the stones and apparently it might mess them up (or so I'm told).

TRUEPRO 06-17-2012 10:41 AM

Only way you would mess them up is to get the mortar smeared all over them. Take you time and make sure to be as clean as possible.

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