How to Seal a Shower Enclosure (Without Losing Your Mind)

28 July 2025 · 6 min read

Spoiler: you don't need to be a plumber, nor have the steady hand of a plastic surgeon.

We've all been there. Water creeping in where it shouldn't. Mould turning up as reliably as an old debt. And that line of silicone that has gone from bright white to... let's say "well-lived".

Sealing a shower enclosure is one of those jobs we put off, and put off... until it becomes urgent. But the truth? It isn't hard. You just need to know how to seal a shower enclosure without making the classic beginner's mistakes (like using too much sealant or, worse still, the wrong one).

In this article we'll walk you through it step by step, with no needless jargon. Just practical, direct, tried-and-tested advice. And while we're at it, we'll settle a long-running dilemma: shower sealant, inside or out?

Why sealing your shower enclosure properly matters

Before we get stuck in, let's ask a simple question: why does sealing a shower enclosure matter so much?

Well, first of all, to stop water ending up on the floor every time you take a shower. But not only that. A poorly applied seal:

ruins the grout between the tiles
lets mould and bacteria thrive
spoils the look of the bathroom (that blackened silicone is an eyesore)
risks compromising the structure of the enclosure itself, especially if it's glass

In short: how to seal a shower enclosure is a matter of function, hygiene and, yes, looks too. And knowing how to seal a shower enclosure the right way spares you these problems.

The right silicone makes the difference (it really does)

Let's pause a moment before getting to the how. Because if you pick the wrong silicone, you can be pinpoint-accurate in your application... yet a few weeks later you're redoing the whole thing.

Shower sealant needs to have very specific qualities:

be mould-resistant, otherwise it will soon fill with black stains that are impossible to shift
withstand damp (it sounds obvious, but not every sealant from the hardware shop genuinely does)
be neutral, that is non-acetic, to avoid corroding materials such as aluminium, glass or treated tiles
be compatible with non-porous surfaces, because a shower is not a skirting board

And then there's the eternal dilemma: clear or white? If you want it to disappear into the wall, go for clear. If you prefer a visible, clean finish, white is the classic choice.

One last thing: if you're wondering how to seal a shower enclosure with metal, glass or PVC profiles, always check that the product states it expressly. Some "universal" sealants are anything but.

And trust us: a professional sealant gun for around 15 pounds saves you a lot of swearing and wasted DIY shower sealant.

How to seal a shower enclosure: the 6 key steps

Right, let's get to the point. Here's how to seal a shower enclosure properly, step by step.

1. Remove the old silicone (patiently)

Arm yourself with a utility knife and some patience. The first thing to do is remove every trace of the old sealant. Scraping it off isn't enough: use a silicone remover to soften the material.

Little trick: an old credit card cut into a blade works beautifully for shifting the most stubborn residue.

2. Clean and dry to perfection

Once the old silicone is gone, clean the surface thoroughly with methylated spirits. The area must be perfectly dry: even a single drop of water would compromise the new shower seal.

3. Choose the right silicone (essential)

Not all silicones are equal. For the bathroom you need a mould-resistant silicone, made specifically for damp environments. If you're still not sure how to seal a shower enclosure most effectively, start right there, with the quality of the material.

4. Apply masking tape (for clean lines)

Want a precise result? Mark off the area to be sealed with masking tape. Leave a 3 to 5 mm gap depending on the thickness you want.

5. Apply the silicone in the shower enclosure

This is the key moment. Load the cartridge into the gun and start sealing the shower enclosure with slow, steady movements. Better to cover a little at a time for more control.

If you're wondering how to apply silicone in the shower enclosure precisely: hold the gun at a 45-degree angle and don't squeeze too hard.

Tip from the precision obsessives: lightly wet your finger with soapy water and run it over the silicone right after applying, to smooth it.

6. Remove the tape and let it cure

As soon as you've finished smoothing, peel off the masking tape straight away. Don't wait for it to dry: you risk lifting the silicone.

Let it cure for at least 24 hours without using the shower. Yes, even if it's Saturday morning and you're running late.

Shower sealant inside or outside?

Here we are at the big dilemma: is it better to seal a shower enclosure on the inside or the outside?

The right answer is: it depends on the type of enclosure. But in general:

Inside: to stop water seeping in between the profiles and the wall
Outside: only if needed for aesthetic reasons or if the enclosure's design calls for it

In many cases sealing on the inside is enough. And no, sealing a shower both inside and out doesn't double the protection. Quite the opposite: it can create condensation between the profiles and encourage mould.

How to seal a shower enclosure without the common mistakes

Over the course of our work we've seen it all. Here are the mistakes to avoid at all costs:

using generic building silicone (not mould-resistant)
applying the silicone to a still-damp surface
skipping the cleaning step
making the bead too thin (it won't cover properly)
putting silicone where it isn't needed (such as over the seals)

Remember: a good shower seal is worth more than a thousand patch-ups.

DIY shower sealant: when it makes sense (and when it doesn't)

We're fans of DIY, but only when it's done well.

Sealing a shower enclosure yourself makes sense if:

you're at least reasonably handy
you have the right tools
you can set aside a couple of hours without rushing

If, on the other hand, you have a glass enclosure with delicate or made-to-measure profiles, it might be worth calling a professional. The risk of doing damage is high, and putting it right can cost a fair bit.

Want a bathroom that stays clean for longer?

If you've just finished your shower seal, this might be the perfect time for a deep clean.

We suggest taking a look at this article on our blog:
Shower Enclosure Lifehack: how to clean it really well

It's a quick read but packed with handy tricks.

Conclusion: sealing a shower enclosure is easier than it looks

We've seen how to seal a shower enclosure simply, safely and stress-free. All it takes is following these steps, having a little patience and choosing the right materials.

Oh, and if you happen to get the whole floor in a mess... don't worry, it happens to the best of us.

Get in touch if you've had a go at sealing your shower enclosure, or if you have a question to sort out. That's what we're here for.

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