[Philj]

I want to seal the holes where the pex comes from underneath the crawl space up through the floors to my fixtures. I want to stop the draft coming through.
The manufacturers instruction say to only use water soluble gypsum based caulking because others might react with the pex. I cannot find anything like that around here and people I talk to that install pex have no clue when I mention water soluble gypsum based caulking. What do people use?

 

[Philj]

It's half inch pex and the hole are 1,1/4" to accommodate the blue plastic pex rings to hold the pex in place I'm not sure if I could stuff the insulation in that small space.
I was td o could use silicone and others have said mono caulk from homedepot. I am not sure if any of those would be okay to use?