Secure Cinderblocks to patio

Old 07-07-12, 11:38 PM
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Secure Cinderblocks to patio


I have almost completed tiling my concrete pad (outside) and will be installing a natural gas fire pit on top of the tile (porcelain tile). I have 2' radius blocks and will line with firebricks (with mortar/fire clay mix) and then cover with pre-fab radius panels. My question is what type of mortar should I use between the radius blocks and how should I (or do I even need to) adhere the radius blocks to my tile? I assume a type N mortar...assuming leftover thinset from my tiling project will not work/won't be strong enough?

Advice/recommendations would be much appreciated.

Old 07-08-12, 02:23 PM
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Not sure you should be anchoring the block frame to the tile if you're mortaring them all tightly against each other, because if you (or anyone else) happen to run the thing wide open, like a blast furnace for a few hours, some of the heat will be migrating through and causing the blocks to lengthen slightly as they warm up. Maybe a better way would be to lay the blocks with open gaps between them--if you do that, then you could anchor them individually with long lag bolts/expansion shields or even rebar stubs epoxied into holes drilled through the tiles' grout lines, projecting a few inches into the blocks' void cavities, then mortared solid. Open gaps between blocks would also provide better air circulation, keeping the blocks cooler and more likely to stay in place instead of expanding/contracting and wanting "to walk" around the patio.

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