standing water on shower sealant

16 Jan 2008
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United Kingdom

The sealant all the way around my shower has come away and we're getting leaks into the walls and out the front of the tray. The sealant is fresh on only a few months.

I've noticed that the top of the shower tray is sloping towards the walls/front of the shower - away from the main area of the tray. So water isn't draining away properly and is staying in contact with the sealant the whole way around.

Will this cause the sealant to rot quickly and to come away from the tray? It wasn't properly bonded to the tray at all last night when I ripped it all off.

I am going to reseal it all but just wanted to know what's the cause of it!


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Make sure everything is scrupulously clean and dry when you re-seal.

Use a good quality sealant not some el-cheapo own brand stuff.

Get in the habit of drying the shower out after every shower - a pain, I know but it will save you a lot of hassle and expense and it reduces condensation in the bathroom, as well as reducing the need for frequent cleaning if your water is hard. We have a thick towelling bath mat, which we use to dry the shower. Our shower still looks as good as new, 3 years after installing.
Thanks Rigid Raider.

So should a good quality sealant be able to cope with a certain amount of standing water without coming away too quickly?

I can cope with having to re-seal every year or two but not every few months.
A true Silicone sealant is good for fully immersed use, make sure it is a good quality silicone, should have a vinegar smell as it cures.
An acrylic sealant is not suitable for immersion.
Make sure it is fully dry, and degreased along the bond line. It needs moisture to cure, so let it get damp, then leave it standing to cure before use as it may be asked to stretch when the tray is used.

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Thanks Mike. Sounds like I'm off to buy some expensive stuff tomorrow - I'd avoided buying UniBond stuff before due to price. Sounds like it is worth the extra.

I don't quite get what you mean about letting it get damp to help cure it. Do I apply the sealant, then let it dry for an hour or two and then apply a bit of water? Won't this top it bonding to the shower tray/wall? (Sorry for basic questions!)
The silicone sealants all need moisture to cure, the chemical reaction then releases "acetoacetic acid",( but there are some non vinegar ones best used near electronic circuits etc), which gives the vinegar smell, if you leave it too dry it will take forever to set. best to use a plant mister after you have it fitted to final shape.

Mike13, that's the first time I've heard of silicon sealant needing water! Whenever I've used it, it has gone of pretty quick and fully cured within a few hours.

deco100 - one other thing that's worth doing is removing the valance and checking that the shower tray feet (if you have these) aren't unscrewing themselves allowing the tray to settle slowly, stretching the sealant. Tightening them up by a turn or two won't harm, I always "lock" mine by standing them on a some sealant or a blob of polyfilla.
Thanks Mike. Sounds like I'm off to buy some expensive stuff tomorrow - I'd avoided buying UniBond stuff before due to price. Sounds like it is worth the extra.

Hey good sealant doesnt have to be expensive. From what ive read on here the best is made by Dow Corning you cant get it in B&Q etc, but its about £3-£6 depending on where you buy it.

Do a search on the Tiling forum and you'll find plenty there, the guys there are always raving on how good it is.

Good luck
well it usually goes off just from moisture in the air, but the wet finger to shape it helps too!!!

I've found that the grout behind the rotten sealant needs scraping out - it's a bit soft and mouldy. I'd put the grout on there originally thinking it would act as a second line of defence but I'm not sure I'll bother this time - I saw a post which said there was no point.

What do people think?

I can't see that having the grout would do any harm but I'll need to leave for a few days to dry which will prolong the whole job.

Thanks for all the tips,
- D1 nhs thanks for the tip off about Dow Corning - I'll try to find it
- mike13, I thought you might mean a plant mister job
- RigidRaider, thanks for the tip but luckily I'm working on a stone tray directly on the floor.
the grout is not needed, you want a good cross-section of silicone to cope with the movement that all buildings have.


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