Grout or caulk for tub expansion joint?
Kimball_house
| Posted in General Discussion on
I need to remove and replace a few sections of grout in a tile tub/shower. At the point where the walls meet the tub is it best to put in grout and cover with caulk, or to just put in caulk? I think this is called the expansion joint.
I have a hand grout saw and also a Fein sander with which to remove grout. Does anyone know whether using the Fein sander to remove grout is tricky or might damage tile? Should I give it a try?
Thanks
Replies
Definitely caulk. And not silicone.
because it doesnt paint?
The problem I have with silicone is that over time the mildew and mold gets behind the seal at the edges, and in corners, etc. A bigger issue I have with silicone is that it doesn't stick to itself. That is, if it ever needs to be removed and replaced there is a great amount of effort needed to remove every last shred of the old caulk before new caulk can be put over it.
Even with the mildew resistant silicone I've seen issues with pockets of mold forming not on the caulk itself but creeping out from underneath the seal.
I will never use silicone in a tub or shower again because of the mildew problems with it and the hassle of replacing it once it does get all moldy.I just tried a brand new caulk by Sashco that is your basic water clean up caulk, but is mildew proof. They guarantee it for 7 years and if it grows mold or mildew before then, they will send someone out replace the caulk.It was pretty easy to apply. My only complaint was it only comes in that little toothpaste style tube, not a caulk gun cartridge.It's too early to comment on the durability of it, but application was easy.This is the stuff:
http://www.sashcosealants.com/Home_Improvement/MildewFree.aspx
Mildew will form on just about anything in a shower or bath. The main problem with silicone is when it's cleaned with strong chlorine bleach. This reacts with the surface and roughens it, creating the ideal place for soap scum to collect and cause mildew.
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If there is grout in that space, then I should remove it?
If the grout is failing, then remove it and replace it with caulk. I prefer tub and tile caulk, but silicone works too since there will never be a need to paint it. There have a lot of caulk discussions and if you do a search for them, you'll find that there are many other choices.
If the grout is not failing, I would leave it alone. This joint (between tub and tile) is unlikely to ever leak because there's a flange on the tub that goes up behind the tile.
If some is failing and some is ok, I would still replace all of it if only for aesthetic reasons, but it's not really necessary.
As long as the joint is less than about 1/4", you won't need to pre-fill it with grout or backer rod, but if it's any bigger, consider using backer rod. It will make for a neater job.
Caulk any place where dissimilar materials meet.
And I've had good experience with silicone.
The hand grout saw works surprisingly quickly. Use a bath-grade silicone that has a mildewcide built in.
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At the point where the walls meet the tub is it best to put in grout and cover with caulk, or to just put in caulk?
Can you post a photo of this 'meeting place'? I'm having trouble seeing where the grout might go.
Normally, the joint between the tub and the bottom row of tile isn't grouted, it either terminates with a row of sanitary cove tile or it is caulked. For once thing, grout doesn't stick to shiny surfaces very well. For another, there is inevitably some movement of the tub relative to the walls caused by cyclically adding and subtracting the weight of water and user, or by rapid thermal expansion of the tub itself due to filling with hot water. That movement would cause grout to crack.
As has been mentioned, this joint is not prone to leakage, because the tub flange extends upwards an inch or so behind the tile. The use of caulk in the absence of sanitary cove tile is thus more of an æsthetic decision than anything else.
If you caulk, I suggest using Mulco Flextra, or a similar thermoplastic caulk. It is impervious to mould, guaranteed for 20 years, and is a joy to work with.
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Most tile suppliers have grout colored caulking just for that purpose.
I dont recall who makes it, but it looks a heck of alot better than the silicone, and holds up better too. It even has a textured sand-like look to it.