Caulk fails at fiberglass tub surface . . .


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Old 01-05-08, 09:11 AM
K
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Caulk fails at fiberglass tub surface . . .

The gap between my tile wall and fiberglass tub ranges from none to about 3/32". The side of the tub and part of the head is on an outside wall and subject to wide temperature changes. I have been unable to get caulk to reliably seal this joint. I have tried different types of caulk and all fail to last six months without leaking.

My method has been to thoroughly clean out the old caulk. I let the joint dry for at least a week. I then fill the tub and clean the joints with rubbing alcohol before applying the caulk. When done, the caulk covers about 1/8" of the tub and tile along the joints. I let it dry for at least three days before use.

In every case, the first symptom of a problem is leakage. Upon inspection, the bond of the caulk to the tub has failed. This is not apparent without very close inspection.

I have tried different caulks including latex and silicone. I have tried adhesive primer on the tub before applying latex caulk. Nothing seems to last.

I have just removed the failed GE Silicone II caulk and will be waiting for everything to thoroughly dry. Meanwhile, I am open to suggestions as to what I can do differently to create a lasting seal.
 
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Old 01-05-08, 09:34 AM
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Caulk

hey Knave
Is this a whirlpool tub by chance? It sounds to me like the tub doesn't have the correct lip around the top for the tile to overhang down in the tub.

I'll also bet that the outer edge of the tub, whatever type it is, isn't supported corrctly. I had this same issue, because the tub was the wrong type (designed for a drop in surround, not tile walls w/shower) and it was installed incorrectly( no edge support and scrap wood under the tub base for support).

You may have some deflection in the floor when the tub is in use, making the problem worse.

Yer doing all the right things for the caulk, you have to find what the underlying problem is.
 
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Old 01-05-08, 09:09 PM
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I think you are probably right about the type of tub. We had the tile and backing material replaced due to water damage from the outside about 5 years ago and there is no lip on the edge of the tub beneath the tile. It just sort of rolls off at the edges. I am not eager to go through the trouble of replacing the entire tub to correct this problem.

It does have proper edge support and doesn't flex or give around the edges. This is a Florida home built on a concrete slab. The base of the tub is supported by the slab and not subject to movement.

I believe that the problem is more temperature related as the tile temperature is affected by outside temperatures. I don't think there is much change in the gap between the tile and tub, but the caulk appears to have enough shear strength to maintain the bond to the tile but fails the tensile bond to the tub.

I have considered injecting epoxy into the gap to bond to the tub, but I worry that such a permanent attempt at a fix may prove impossible to reverse if it doesn't work. I am open to any ideas anyone may have.
 
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Old 01-05-08, 10:20 PM
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Have you tried Polyseamseal's Tub and Tile Caulk? http://www.polyseamseal.com/FAQ.aspx
 
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Old 01-06-08, 12:10 PM
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Originally Posted by twelvepole
Have you tried Polyseamseal's Tub and Tile Caulk? http://www.polyseamseal.com/FAQ.aspx
I'm pretty sure that I used that about two recaulking projects ago.

One friend recommended trying butyl rubber caulk, but I haven't located such a product.
 
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Old 01-06-08, 12:26 PM
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I haven't used any butyl caulk in years. It won't stick as well as G.E. silicone so I wouldn't bother with it.
 
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Old 01-07-08, 11:20 AM
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Thanks for your comments.

The caulk I just removed was GE Silicone II bath caulk and it did not remain stuck to the tub. Is there anything I can do to better prepare the fiberglass tub surface to ensure lasting adhesion of the silicone caulk? Is there a better solvent than isopropyl (rubbing) alcohol for this purpose? Would scuffing the tub surface at the joint with a Dremel wire wheel help?

I plan on waiting a week or two before recaulking in order to let everything dry out.
 
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Old 01-07-08, 03:55 PM
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Scoring the surface to get better adhesion should help.

The biggest problem is making caulk do something it isn't really designed for - a substitution for the missing lip
 
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Old 01-08-08, 07:20 AM
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I know that if the lip was present, I wouldn't have the leaking issue. However, I wouldn't say that caulk wasn't designed to provide a joint seal that prevents leaking. Perhaps many caulk applications leak after several months, but don't show any obvious symptoms as the lip prevents leakage.

I know that the first time I was troubleshooting the leak, I thought it had to be a leak in the shower pipe within the wall as it only leaked while using the shower and the caulking application looked good. Then I poured some water on the edge of the tub where it meets the tile and it started running beneath the wall onto the slab in the adjoining room. I am sure that a lip would have prevented this.
 
 

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