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alan_m

On 04/09/2020 22:15, wrote:
On Friday, 4 September 2020 21:14:22 UTC+1, alan_m wrote:
On 04/09/2020 18:30, Kathy A Yarbrough wrote:
I have a hairline crack in my fiberglass tub. It is very small. Could it
leak down o to the floor below?

Yes

The bathtub will have a strengthening piece of chipboard on the
underside of the base. This will get damp and very soon get to the
stage where has the strength similar to weetabix that has been sitting
in a bowl of milk for half an hour. It will not longer support the base
of the bath and the crack will get significantly worse very quickly.
If when standing in an empty bath the base moves or bends significantly
then perhaps this strengthening board has already started to degrade.

It may be wise to remove the bath side panel and support the base of the
bath with scraps of wood wedged between the floor and the base of the
bath, especially in the area of the crack.

You could use a FINE fibreglass mat and resin (aka car body repair kit)
to seal over the top of the crack but it is unlikely that the finished
result will be cosmetically pleasing. You will have to scuff the
existing bath finish to get the repair to bond to the bath. If the resin
remains sticky after,say, 24 hours sprinkle some talcum powder over the
repair

Before my (planned) bathroom refurbishment I had a similar crack in a
plastic (fibreglass) bath and managed to keep the floor dry for around 6
months by repairing. However the problem did get worse by the time the
bath was removed and I doubt if the bath could have lasted much longer.

The op might like to consider the cost of the damage from the bath bursting. If it's where that doesn't matter, then sure it can be bodged up with fibreglass mat & resin, or even just cement/concrete. For the latter, put a plastic bag on the floor, pile the mix onto it & push it sideways until it presses against the bath's underside. A complete bodge of course. Probably best to do both, GRP repair then support with cement.

Agreed, but either bodge repair is only a short time solution.

The problem is if the crack is in the base of the bath. The
strengthening board will be either glued to the base of the bath or
incorporated within the fibreglass. This will prevent localised
repairing from the underside. Water penetrating the crack will run along
the whole length of this chipboard which usually extends three quarters
of the total length of the bath. Once the chipboard has lost its
integrity because it has become wet/damp then the base of the bath will
flex even more and the existing crack will open up more and, in my
experience, other cracks will appear. Any rapid failure is likely to
occur when someone steps into a bath full of water. Even if the bath is
further supported underneath a large amount of water can leave from a
relatively small or thin crack before it can be emptied via the plug hole.

These baths are very brittle and when I removed mine it was disposed of
in 3 rubble sacks. A couple of blows with a sledge hammer easily broke
into large pieces and stamping on it wearing my steel top capped boots
further reduced to very small pieces. The gell coat easily parted from
the underlying fibre mat which possibly indicates that once cracked
water can also penetrated underneath the gell coat. My old bath was 25+
years old.

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