Wondering how to replace vertical shower door seal without calling a plumber? If water is leaking from the side of your shower door and you already have a new seal ready to fit, this is usually a simple DIY job you can do with basic tools.
The key is to remove the old seal carefully, clean the glass edge, cut the replacement to the right length and push it on the correct way round.
In this guide, we’ll walk you through each step so you can fit your new vertical shower door seal properly and check that the door is watertight before using the shower again.
*Note: This guide also applies to magnetic shower seals.
What is a Vertical Shower Door Seal?
Often called a side shower door seal, it is a precision PVC strip designed to bridge the gap between glass and wall, or between two glass panels.
Whether for pivot doors or sliding systems, a high-quality vertical glass seal is your most cost-effective defence against persistent bathroom leaks.
If you are not sure whether you need a bubble, Y-shape, H-shape or magnetic profile, our vertical shower seal guide explains the main side-seal types.
| Feature | Magnetic Seals | Side Seal Strips |
|---|---|---|
| Best For | Double doors | Glass-to-wall/Double doors |
| Mechanism | Snap-shut magnets | Flexible soft fins |
| Installation | Push-on PVC | Push-on trimmable |
When Should You Replace a Vertical Shower Door Seal?
Worn seals are the #1 cause of leaks. Look for these key signs:
- Visible Damage: Cracking or hardening of the PVC.
- Discolouration: Yellowing or stubborn limescale.
- Poor Fit: Seal no longer stays snug on the glass.
- Leaks: Water escaping during use.
Step 1: Remove the Old Vertical Shower Door Seal
Start at the top and gently peel the old seal away from the glass.
Pull it down slowly. If it is old, mouldy or brittle, it should slide off easily. Remove any broken pieces left on the glass edge.
Step 2: Clean and Dry the Glass Edge
Wipe the exposed glass edge with alcohol or clean water.
Remove soap residue, limescale and mould so the new seal can grip properly. Dry the glass fully before fitting the replacement.
Step 3: Measure and Trim the Replacement Seal
Measure your glass thickness and seal length, then mark the new seal to size.
Cut it carefully with sharp scissors or a fine-tooth saw.
Need pro tips? See our how to cut a shower screen seal.
Step 4: Fit the New Vertical Shower Door Seal
Steady the glass with one hand.
Use the Hook Trick: hook one edge of the seal onto the glass first, then let the glass gently stretch open the U-channel as you slide it on.
Press the seal in bit by bit from top to bottom, making sure it sits evenly on the glass.
Step 5: Check the Door and Test for Leaks
Give it a firm tug. If it takes significant force, around 50N, to move, you have a secure fit. If it feels loose or slides off easily, you may need a different glass thickness size. Close the shower door and check that there are no visible gaps before using the shower.
Watch How to Fit a Vertical Shower Door Seal
See how the seal hooks onto the glass edge and slides into place before you try it yourself.
Common Mistakes When Replacing a Side Shower Door Seal
Even a new shower door seal can leak if it is fitted incorrectly. Avoid these common mistakes before using the shower again.
Choosing the Wrong Glass Thickness Size
If the seal is too loose, it may slide off the glass. If it is too tight, it can be difficult to fit and may damage the U-channel.
Always match the seal to your glass thickness.
Cutting the Seal Too Short
A small gap at the top or bottom can let water escape.
Measure the glass height carefully and avoid over-trimming the replacement seal.
Fitting the Seal the Wrong Way Round
If the seal has a fin, lip or magnetic edge, check which way round a shower seal should face before fitting it.
If it is installed backwards, the door may not close properly or the leak may continue.
Skipping the Cleaning Step
Limescale, soap residue and mould can stop the new seal from gripping the glass.
Clean and dry the glass edge before installation.
Using a Hairdryer
Avoid heating the seal to make it fit.
Heat can damage the rigid U-channel. If the seal feels too tight, check whether you have the correct size.
For more practical fitting and care advice, see our shower seal fitting and maintenance guides.
Why Is My Shower Door Still Leaking After Replacing the Seal?
If your shower door is still leaking after replacing the vertical seal, do not remove it straight away. The new seal may be fitted correctly, but the leak could be coming from another weak point around the door.
If you are not sure whether the bottom seal or vertical seal should be fitted first, read our guide.
Ready to fix the side leak? Browse our vertical shower door seals and choose the right size for your glass thickness.