Last updated: 7 May 2026
If water is leaking from under your shower door, the bottom seal may be worn, cracked, loose, or the wrong size. Replacing it is usually a simple job, provided you choose a seal that matches your glass thickness, door width, and the gap between the bottom of the glass and the shower tray or floor.
In this guide, we’ll show you how to remove the old shower door bottom seal, measure correctly, cut the replacement seal to length, and fit it so it helps direct water back into the shower area.
Before you start, check that your replacement seal is suitable for:
- the thickness of your glass
- the width of your shower door
- the gap below the glass
- the shape of your existing seal or the type of leak you are trying to fix
If you still need a suitable replacement, browse our shower door bottom seals for different drip rails, fin heights, and glass sizes.
Before You Start
In most cases, you do not need a plumber to replace a shower door bottom seal.
However, the correct fit matters. A seal that is too loose may slip off. A seal with a fin that is too long may drag against the tray and make the door harder to close. A seal that is too short may not reach the tray properly and may still allow water to escape.
Fitting a Seal for an Over-Bath Glass Screen?
If you are working on a over bath panel, head over to our specific Shower Screen Installation Guide. For standard pivot or sliding shower doors, stay right here.
How to Remove the Old Shower Door Bottom Seal
A good bottom seal should grip the glass firmly during daily use, but it should still be removable without tools in most cases.
- Open the shower door fully.
- Hold the soft fin or lower part of the old seal.
- Pull the seal straight down from the glass.
- If it feels tight, apply steady pressure rather than twisting it from side to side.
- Clean the bottom edge of the glass before fitting the new seal.
Avoid using sharp tools against the glass, as this may scratch or damage the panel.
If the old seal has become stiff, yellowed, mouldy, or cracked, it is usually better to replace it rather than trying to clean or reuse it.
For more detail on seal grip and material quality, see our shower bottom seal quality guide.
How to Install a Shower Door Bottom Seal
Now for the fun part—fitting your new seal.
Check the Direction First
Before fitting the seal, check which way the drip fin or deflector should face.
The general rule is: The drip fin should face inside the shower area.
This helps guide water back towards the shower tray instead of allowing it to run out onto the bathroom floor.
If you are unsure which way round your seal should go, see our guide on which way round a shower door seal should face.
The "Snap-On" Method
SIMBA shower door bottom seals are designed to grip the glass firmly. For this reason, we recommend pressing the seal onto the glass from below rather than sliding it on from the side.
Line it up: Match one corner of the seal’s U-channel to the bottom edge of your glass.
Use this corner to gently stretch open the channel—this gives you just enough space to snap it onto the glass.
Press the seal upwards onto the glass using the palm of your hand. Work along the door gradually until the full length is fitted.
Check that the seal is seated evenly across the bottom of the glass.
You should not need glue, screws, or silicone for this type of seal. The seal should hold in place through the grip of the U-channel.
If your shower also has a vertical side seal, fit the side seal first where appropriate, then measure and trim the bottom seal so it sits neatly against it. This can help reduce the chance of water escaping at the corner.
For more detail, see our guide: Bottom or Vertical Seals — Which First?
Still unsure? Watch our 1-minute installation video:
Cutting the Seal to Length
If the seal is longer than your shower door, mark the required length carefully and cut it with a fine-tooth hacksaw, utility knife, or suitable PVC cutting tool. For a cleaner cut without crushing the U-channel, follow our guide on how to cut a shower screen seal.
Test for Leaks
Once the seal is fitted:
1. Close the shower door.
2. Turn on the shower.
3. Let water run against the door as it normally would during use.
4. Check the outside of the shower for leaks.
5. Open and close the door to make sure the seal does not catch excessively.
⚠️ Pro Tip: Keep the water under 60-70°C. Boiling hot water can warp the soft fin and ruin the seal.
Example of heat-damaged soft fins
Still Seeing Water on the Floor?
If water is still escaping after fitting a new bottom seal, check the following:
Is the Gap Uneven?
Some shower trays or floors are not perfectly level. If the gap is larger in one area, the seal may not make contact along the full width.
Is the Fin Height Correct?
If the fin is too short, water may pass underneath. If it is too long, the door may drag or fail to close smoothly.
Is Water Escaping from the Side?
Sometimes the leak is not from the bottom edge alone. Water may be escaping from the vertical side of the door or from the corner where the bottom and side seals meet.
Do You Need a Threshold Bar?
In some cases, a shower threshold strip or water bar may help by giving the bottom seal a raised surface to meet. This can be especially useful where the tray edge is low or the floor gap is uneven.
For a full checklist, see our guide on why your shower door is still leaking.
Frequently Asked Questions
Why is my new shower door bottom seal making the door hard to close?
This is usually caused by friction. If the bottom fin is too long, it may press too firmly against the shower tray.
The best solution is to choose a seal with a shorter fin height. Always measure the gap below the glass before ordering.
Can I use these on curved shower doors?
Yes. You just need to select a curved shower door seal. The installation method and "inward-facing" rule remain exactly the same.
How often should I replace my shower door seal?
There is no set rule. However, you should fit a new one if you notice:
- Yellowing or stubborn mould.
- The seal feels loose or slips.
- The soft fins are cracked or torn.
I’ve fitted the seal, but it’s still leaking. What now?
Check the floor level, fin height, and the corners of the door. If the gap below the glass is uneven, the seal may not reach the tray in every position.
A threshold bar may help in some situations, especially where the seal needs a more defined surface to close against.
Do I need to use silicone or glue?
No. For clip-on shower door bottom seals, silicone or glue is usually not required. The seal should grip the glass through the U-shaped channel.
Using adhesive may make future removal more difficult and is not normally needed if the seal is the correct size.
Can I use a seal without an old-fashioned aluminium rail?
In many cases, yes. Modern shower door seals can provide a cleaner, more frameless look, but you should check that the new seal suits your glass thickness and gap size before removing any existing parts.
What if my gap is too small for a standard seal?
For very tight gaps where a standard U-channel will not fit, first check which seal works best for a small shower door gap. In some cases, a self-adhesive shower seal may be more suitable because it sticks directly to the glass surface and does not need clearance under the door.
A Simple Fix for a Common Shower Leak
Replacing a shower door bottom seal is one of the simplest ways to reduce leaks under a shower door. The key is to measure carefully, choose the right profile, and fit the seal in the correct direction.
For more practical fitting and maintenance advice, see our shower seal fitting and maintenance guides.
At SIMBA Seals, we supply a range of shower door bottom seals for different glass thicknesses, fin heights, and shower door types.
Browse our shower door bottom seals to find a suitable replacement.
(Free UK delivery & 10-month warranty included)
Got a specific question? Not sure which fin height you need? Drop it in the comments below—Laura and the team are always here to help you get that 100% watertight fit!
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