Good Morning. Does anyone have recommendations on how to repair the "seal" between a stone cap and a fiberglass hot tub? Also, I need to repair the grout on the stone cap.
I found an old thread that recommended MAPEI outdoor pre-mixed grout, but all the install videos I see recommend putting a foam backer for the grout and the cap seal. Is that necessary to keep the grout/sealant in place?
Finally, the old seal material is as hard as a brick and I cannot chip it out. I'm guessing a cutting wheel/grinder?
Photos attached.
Thanks for any input you have.

I found an old thread that recommended MAPEI outdoor pre-mixed grout, but all the install videos I see recommend putting a foam backer for the grout and the cap seal. Is that necessary to keep the grout/sealant in place?
Finally, the old seal material is as hard as a brick and I cannot chip it out. I'm guessing a cutting wheel/grinder?
Photos attached.
Thanks for any input you have.

