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adhesive for flagstone to concrete

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#3 ·
Thinset will work,but it doesn't have any body to it to adjust for the varying thickness of stone.I would use a thin bed of some rich morter,possibly spec mix in combination with the thinset applying the thinset to the concrete and the stone with a thin morter joint between or mixing the two together creating a thinset with body.
 
#5 ·
jvcstone said:
Or you could use the granite/marble medium set from HD. Has a little more body and can be used up to 3/4 inch thick. Would work best if all of the stone was of the same thickness.
JVC
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I've seen the G/M set but have never used it.I take it's basically thinset with a larger grit. Sounds like a good idea.A latex additive or concrete glue wouldn't hurt either with the thin bed,especially if freezing or ice is a problem.
 
#6 ·
g/m

i have never used this product either,but the house i am on now has a boat load of slate i have to lay and that is what they have to lay it with.the h/o has layed the slate in the laundry room already and it seems to work very well.i hope it does because the slate tiles are not very equal in thickness.
 
#8 ·
dirt diggler said:
yeah Thinset was what I figured

hope it works ...

hahah guess we'll find out:blink:eek:
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Not sure what kind of flag you're using,but you're liable to get a lot of voids with straight thinset.The mediumset as jvc suggested sounds better.
I like to pack in the joints as i go, leaving them down only enough for grout.About 1/4 ".It helps lock in the stone.Wetting the back helps with adhesion,parging with thinset or neat is better.Make sure the back is clean.Many times people will wonder why their grout joints are cracking when it's really a void and the stone is actually flexing(quartzsite especially)or come loose.
 
#9 ·
When you come across a situation like yours (loose piece of flagstone) you can save time/avoid Portland and Sand, just grab a tube of GatorBlock XP Adhesive (5 bucks and a caulk gun). You can call their tech support (866) 212-1611 for more info, I've called them before for another application and the manager there (Craig) was great.
Flagstone Step Repair:
The trick is to apply proper beads (no pancakes in the corners) smooth it out so it's even and definitely rub the stone back and forth a bit to be sure.

Whether you eyeball it or use a level the following is key, b/c adhesives expand when curing, SO IF the flagstone PIECE you're affixing IS THIN (less than 1/2") definitely be sure to leave some weight on it overnight. That way you'll come back in the morning and it will look dynamite. Good luck fellas!

Gregg
https://clarity.fm/greggkennelly
 
#10 ·
Gator glue or some type of polyurethane glue would be fantastically expensive, not to mention that in most applications you wouldn't want to use beads since even after compression, they will still leave subsurface voids which in a freeze/thaw climate would be unacceptable.

The product I would use for this application of flagstone is the same stuff I would use when tiling a church staircase or the steps up to a public building - Karalastic/Karabond. It works even better with flagstone and coats can be as thin as 1/4" or as thick as 3/4", spread with a notched trowel. Since it is so sticky it's from 2-3 times as slow to use as compared to mortar.
 
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