Sealing Shower Enclosure - Tile Advice

[markgannon]

Hello. I've received conflicting advice on whether the bottom horizontal piece of a shower enclosure should be sealed with silicone on the outside only OR both on the inside and outside. See images. The original installer sealed both inside and outside when the home was built. It lasted 15 years before it started to mold on the inside. I removed it, cleaned it and re-installed (siliconing the inside and outside) and it only lasted a year before deteriorating again. Should I only be siliconing the outside?

 

[Ben-gee]

Yes , only seal the outside.

 

[markgannon]

Yes , only seal the outside.

Thanks. If I'm only sealing the outside should I be using an adhesive under it to keep it from moving? What type would you recommend sir?

 

[Ben-gee]

No adhesive necessary, just use a good quality silicone on a properly prepared surface.
I clean with isopropyl alcohol and then use Dow Corning silicone (and yes I know they changed the name)