Compound for levelling a stone sill
Hi, I’m about to install french patio doors in a opening that has a solid limestone sill. Over the length of the 5′ sill, it’s out of level by 1/8″. I know that’s not much over 5′ but I worry that the doors will not function smoothly if I leave it like that.
I don’t want to shim it with wood as that could rot over time, so I was thinking of a very thin coating of thin set mortar. However I worry even a thin set mortar coating will crack under the weight of the doors.
Can anyone help me with any suggestions in this regard? Actually, as I was just typing this I thought of perhaps shimming with some aluminum or sheet metal…any thoughts on that.
Thanks
Bill.
Replies
Never seen thinset ever crack under any tile when its main base is solid.
Bill, it has been my experience that the door assembly either in the factory or in your backyard (depending on the manufacturer) is likely to be more than an eighth off. Perhaps it'll be the opposite eighth and you'll be right on.
After you install or fab your sill pan, apply Urethane caulk across the whole pan. Shim with cedar shingles at points necessary to level and straighten the sill. Stay off the sill till the Urethane cures if at all possible. You have the option of using strips of metal, thin plastic shims (for that purpose) or other non wood product. You can cut them back and leave them, touching up the caulk with a continuous bead when done.
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Use Non Shrink Grout. That's the exact type of application it's intended for, not necessarily door sills but support of heavy machinery and the like. Thin set mortar probably OK too.
I agree with a couple others on here- non shrink grout if you're stuffing it in with the stone in place, or mortar if you're resetting it.
I used to use non shrink grout on suspension bridge towers, so I have no doubts about it's ability to do the job- just shim the limestone up with flat stock steel, then mix up a bucket of grout, stuff it in, finish all the edges at 45 degrees out, and you're done.
zak
"so it goes"