# Cracks in Fiberglass Tub



## sweaty (Jul 18, 2008)

I have a two story house built in 1977. The dining room ceiling has water stains and collapsing drywall. Above it is a one-piece fiberglass tub and shower enclosure. We could not find any pipe leaks and the caulk looks good. There are many hairline cracks on the bottom of the tub. Could these cracks be the cause of the leaks?

If so, is there a sealant I can put on it? Replacing it would be too disruptive and expensive.


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## Mike Swearingen (Mar 15, 2005)

I too have 1977 upstairs and downstairs (over crawlspace) one-piece fiberglas tub/shower units that would be very difficult to replace.
I seal cracks and chips in the bottom of them with bright white enamel appliance touch-up repair liquid, available at appliance and hardware stores.
It comes in a little bottle with a cap brush similar to nail polish and dries hard as a rock.
I clean the chip or crack up and dry it good with a hair dryer. Then I apply the touch-up and smooth up the edges with a Q-tip dipped in acetone (nail polish remover). Let it dry overnight. It will shrink a bit when it dries. To fill a hole better, you can apply a second coat and let that dry overnight.
Then I cover the tub bottom with a bath mat.
Works for me. An inexpensive trick that I've been using for years on them.
Good Luck!
Mike

P.S. The cracks are most likely the source of the leaks, but if you're still getting leaking after you seal them, it may be that the plumber's putty under the lip of the drain has gotten old and is leaking when the weight of a tub full of water and/or the bather is in it. It may not leak with just the water in it, but when someone steps in to take a shower or bath, then it might leak. You just unscrew the drain and replace the putty with fresh in this case. Good luck!


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## ArmchairDIY (Oct 21, 2009)

I also doubt that the hairline cracks are the source of your problem, but it's possible. 
I have no experience repairing hair line cracks, but the finish coat of fiberglass is called gel-coat. Maybe a google search for gel-coat repair might yield some information. But I think it may be a rather involved process.

Could you put some water in the tub and some food coloring. Then the leak may be more visible. On the down side it may stain your hairline cracks though. Just a thought.


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## Thurman (Feb 9, 2009)

My first thought is not of repair, but of improper fiberglass tub/shower surround installation. If you have evident cracks showing this IMO, is an indication that the unit was not put in with any support underneath to absorb the flexing of the tub bottom as a person stands/sits/lies in the tub. These units should be put in with a bed of mortar, or grout, some even use Plaster of Paris as a support bed. I like to put water in the unit half-full (or is it half-empty?) to allow the unit to set as if it would be used. I have repaired two (2) of these units after they were in place. I used simple ole' Super Glue to seal the cracks, after cleaning and drying them thoroughly. I bought about three (3) feet of stiff, semi-clear plastic tubing at a big box store which would must slip over the nozzle of a can of expanding foam. On one of the units I accessed it from the half-bath side, the other from a bedroom. After removing the baseboard and cutting out about a foot of drywall so I could see under the tub. I taped the tubing to a stick I cut about one-inch square for control, and shot the expanding foam under the tub, half-full of water. It's hard to gauge as to how much is enough, not to much as to cause the tub bottom to push up, but enough for support. This trick worked for me, twice now, so it may work for you, if needed. Good Luck, David


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## sweaty (Jul 18, 2008)

I tore out the ceiling below and inspected. There is no sign of water from the drain seal or underneath the main body of the tub. Right above the water stain are the hot and cold supply pipes and the bend of the drain pipe. 

The supply pipes (copper) have tarnish on them and the drain pipe has a dark blob on it. It looks like there has been water. I let the shower run, both hot and cold, for much longer than a shower would last, but no water came out. Any other thoughts?


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## Mike Swearingen (Mar 15, 2005)

Haved someone stand or sit in a tub full of water to see if the drain leaks. The added weight of a person or water can make that happen if the plumber's putty seal under the drain lip has deteriorated.
Mike


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## litzhoff (Nov 29, 2009)

I had the same problem. Took me a month to figure it out. The leak took 
out my first floor ceiling. Look at your drain. Pull the strainer off.
When you put weight around the drain this may cause a hair line shift in the
drain pipe directly below the drain. Get silicon seal line the drain connection
making sure no water can leak out sideways around the connection
Good luck
[email protected]


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