Silicone sealant can really add that final, finishing touch to a new bathroom when applied correctly.
Unfortunately, for some people, this does not always end up being the case.
All too often I see a beautifully tiled and decorated bathroom, almost ruined due to poor sealant application.
And it’s not only the aesthetics of the job that’s the issue.
The problems created by a poorly sealed bath or shower can lead to some catastrophic leaks. The water damage created can end up costing the homeowner thousands of pounds to repair.
Don’t let this happen to you.
In this article, i’ll be discussing the 6 most common mistakes people make when applying silicone sealant.
Mistake # 1: Licking and using your finger to smooth the silicone.
This technique is bad for a number of reasons.
First of all, by licking your finger before you smooth the silicone, you are essentially transferring the bacteria from your mouth to the wet sealant. And as the sealant hasn’t yet cured, the bacteria can easily penetrate and spread, causing early onset mould.
Secondly, using your finger to tool the sealant can be a messy business, especially if you’ve gunned out too much in the first place. You are likely to smear the sealant along the bath or tiled surface, which looks terrible once it dries.
Thirdly, you may be taking away too much silicone if you use your finger. Rather than a nice straight, solid bead of sealant, which is completely watertight, you are left with nothing more than a paper thin layer of silicone skin. Which in time will tear, defeating the object of applying the silicone in the first place.
Mistake # 2: Using the wrong type of silicone
Not all sealants are created equal. And just because something is branded as a “bathroom sealant”, doesn’t mean it’s suitable for all bathrooms.
This is especially the case when it comes to bathrooms that have natural stone (marble, travertine, limestone etc) tiles. Regular sanitary sealants (Dow 785, Mapei AC etc) that are acetoxy curing can be very damaging to these types of surfaces. The acidic nature of the silicone can leave burn marks and stains on the stone, which are very difficult to remove.
Acetoxy sealant will also not bond to the stone sufficiently enough to keep the area watertight. You can always tell when an acetoxy sealant has been used on a stone, because it peels with very little effort.
If you are having stone fitted in your bathroom, make sure the silicone used is neutral curing. This type of sealant is perfect for sensitive substrates such as marble and limestone.
On another note, there’s been a few occasions where customers have used decorators caulk instead of silicone! This is never a good idea.
Caulk isn’t flexible enough to keep a bath or shower water tight. As the bath or shower tray moves, the caulk will crack. It’s also a complete nightmare to remove as it goes rock hard.
DO NOT under any circumstances use decorators caulk as a sealant.
Mistake # 3: Not sealing wall corners in showers
Just because the vertical wall corners in a shower are grouted, doesn't mean it will remain watertight.
Over time, the grout in these corners tend to crack due to movement and settlement.
ALWAYS seal your wall corners!
Mistake # 4: Applying new sealant over old
Silicone by its very nature is designed so that nothing will stick to it. That includes new silicone.
I’ve lost count of the number of times i’ve gone to a job and had to peel away multiple layers of mouldy sealant. If someone has a leak in their shower or a bit of mould that they can’t clean, the first course of action seems to be to squirt some more sealant over the top.
I completely understand the logic, but it actually makes the problem worse. Water is able to get in between the layers, which then stagnates, creating more mould.
What you need to do is remove the old sealant first. See our article “How to completely remove old silicone sealant - The pro 4 step method” for information on how to do this.
Mistake # 5: Not cleaning the joints sufficiently before sealing
One reason silicone may not stick to a surface sufficiently is because the joint may be dirty. Any small amount of dust or debris will prevent the sealant from bonding enough to keep it watertight.
Before applying any silicone whether it’s around a bath or shower tray, floor perimeter or window, I always recommend degreasing the joints first.
To do this simply apply a small amount of methylated spirit to a rag and wipe the joints clean.
Mistake # 6: Not filling the bath up before sealing
Before sealing a bath you should always fill the bath up first.
The reason for this is simple. Bath tubs move. So the water weighs the bath down, and opens up the gap between the tiles and the edge of bath.
You are then able to use the appropriate amount of sealant required to sufficiently fill the joint, providing a watertight finish. You then leave the water in the bath while the silicone cures.
If you seal a bath without filling it up, the next time you use it, the bath will drop slightly, which will then pull on the silicone. The silicone could then come away from the tiles leaving it open to leaks.
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