What adhesive to use for attaching limestone to drywall on a vertical surface
I am in the process for remodeling my wood burning fireplace at home. I have purchased limestone for the project, and have custom cut and polished pieces for the job. These pieces (2 legs, 1 header, and 1 riser) will be set in place around the (E) metal firebox flush to the wall. The company that I have purchased the mantel from (but not the limestone) called Mantels Direct recommends Leech F26 heavy duty construction adhesive for attaching the limestone to the vertical drywall surface. The only problem is, they don't sell this product in California where I live.
Please advise what other adhesive I can use that is similar to Leech F26 that will get the job done. I went to Home Depot, and the closest thing I could find to the Leech product was Loctite PL375 heavy duty construction adhesive.