Sealing around tub silicone or modified stuff?

[Fanatical Meat]

@Greenman I respect your opinion

I need to re caulk my bathtub. Should I use a pure silicone or one of the new modified silicone?
I have a moderate sized gap between the 1960 tub and a surround someone added at some point.

Choice #1


Choice #2

 

[Greenman]

I don't like silicone at the tub /tile seam. It almost always gets mold behind it and it's a nightmare to remove the stuff. I always used dap tub and tile caulking. Holds up reasonably well, and is removeable.

It's been my opinion for years that silicone shouldn't be sold to the general public as the majority of time's it's incorrectly used and creates more problems than it solves. It's a great product used correctly, and a nightmare when poorly installed or in the wrong location.

 

[Fanatical Meat]

I don't like silicone at the tub /tile seam. It almost always gets mold behind it and it's a nightmare to remove the stuff. I always used dap tub and tile caulking. Holds up reasonably well, and is removeable.

It's been my opinion for years that silicone shouldn't be sold to the general public as the majority of time's it's incorrectly used and creates more problems than it solves. It's a great product used correctly, and a nightmare when poorly installed or in the wrong location.

Good summary that is pretty much my opinion on silicone.
I have a good sized gap, like finger sized gap. Would it be wise to use some window expanding foam to seal and then cover that with caulk?

 

[Greenman]

Good summary that is pretty much my opinion on silicone.
I have a good sized gap, like finger sized gap. Would it be wise to use some window expanding foam to seal and then cover that with caulk?

I wouldn't use foam at all, grout it. There is a particular brand that will get you the best results, and I can't remember the name right now. I'll do an edit when I manage to get my brain working. May need a jump start.

Prism! that's the stuff you want to use. If you develop a crack at the seam later (and it will crack) then caulk it.

 

[Fanatical Meat]

I wouldn't use foam at all, grout it. There is a particular brand that will get you the best results, and I can't remember the name right now. I'll do an edit when I manage to get my brain working. May need a jump start.

Prism! that's the stuff you want to use. If you develop a crack at the seam later (and it will crack) then caulk it.

Yes! I almost used prism for a back splash.
So to confirm, just use grout no caulk (for now) or grout to fill gap then caulk?

 

[Greenman]

Yes! I almost used prism for a back splash.
So to confirm, just use grout no caulk (for now) or grout to fill gap then caulk?

Just grout, then caulk when it cracks.
Prism is quality grout. The fellow who used to do most of my tile work flat refused to use anything else.

 

[jmagg]

OP never called out a tile surround.

 

[Fanatical Meat]

OP never called out a tile surround.

Good point it’s not tile, it’s fiberglass or something similar

 

[herm0016]

wait! the gap between the tub and upper surround should not be caulked generally.

if it's tile, the tile is not a waterproof barrier, the waterproof membraine should be behind the tile and this gap allows water that gets behind it to drain out and air to get in. I have recaulked and repaired grout and tile showers that when caulked improperly and the then removed, gallons of stinky water drain out from behind the tile.

when fiberglass or similar this joint is normally "shingled" or lapped so that water would have to travel several inches up to get past this joint. when its left open it provides a gap that can dry out instead of leaky caulk that traps water behind it and molds.

give us some pictures and more details. your situation could be different but its likely this should not be caulked in the first place.

and @Greenman is correct about silicone. very few correct uses for this product. I'm a fan of OSI quad and their other products. SashCo also makes some great sealants. just remember, caulk is not a waterproofing strategy, it's a band-aid.

 

[Greenman]

Good point it’s not tile, it’s fiberglass or something similar

That pretty much changes everything, I just assumed tile, and I shouldn't have. My apologies. Don't use grout, don't do anything until you know what you're dealing with. Could you post a picture?

 

[Greenman]

OP never called out a tile surround.

Very good point, and a good catch.