How to replace shower screen seals

What you need

• Craft knife with a new blade and a metal ruler
• Callipers or a millimetre ruler
• Hairdryer
• Old toothbrush and a sponge
• Towel for the tray
• Phillips screwdriver if the door has to come down
• Seal strip of the correct profile and thickness: drip seal with lip, H closing strip or magnetic seal for 4, 5, 6 or 8 mm glass (6 to 15 euros per metre at Leroy Merlin, Bricodepot, a hardware shop or the manufacturer's website)
• Cleaning alcohol
• Cleaning vinegar or limescale remover (Viakal)
• Soapy water in a spray bottle so the seal slides on

Step by step

1. 1

   Identify and measure the seal

   Find the failed seal by showering with the door closed and looking from outside. Pull off a piece or all of the old seal from one end. Measure the glass thickness at the edge and the total length of the seal. Photograph the orientation of the lip or fin.

2. 2

   Buy the right strip

   Take the piece of seal to the shop or look up the replacement by reference. Buy the same profile or the universal of the same thickness, with 20 cm to spare. For magnetic seals, buy the pair.

3. 3

   Take the door down if necessary

   The bottom drip seal slides along the bottom edge; if the bottom profile leaves no room, release the bottom rollers, lift the door and take it out onto a towel. Vertical closing strips are replaced with the door hanging.

4. 4

   Remove the old seal and clean the edge

   Pull the old seal from one end; if it is stuck with limescale, run the craft knife carefully between seal and glass. Clean the edge with limescale remover and the brush, rinse, wipe with alcohol and dry completely. Check there are no traces of PVC left.

5. 5

   Cut the new seal

   Measure against the glass and cut with the craft knife and the metal ruler, square, 3 to 5 mm longer than the measurement. At corners where two seals meet, cut at 45 degrees so they fit together.

6. 6

   Warm and fit the seal

   Run the hairdryer over the strip for a minute to soften it. Spray a little soapy water on the glass edge. Push the seal on starting from one end, pressing along with your thumb, with the lip or fin facing as in the photo (the drip seal with the lip facing into the shower).

7. 7

   Hang the door and test

   Put the door back, adjust the rollers if they have moved and close it. Check that the closing strip touches along its full height and that the magnetic seals attract. Test shower and check the floor with dry paper.

Which seals a shower screen has and which one has failed

Bottom drip seal. Runs along the bottom edge of the doors and the fixed panel. It has an angled lip or fin that directs water back into the tray. When it hardens or splits, water escapes under the door onto the bathroom floor. It is the seal that gets replaced most.

Vertical closing strip. Runs along the vertical edge of the door that closes against the fixed panel or the other door. It can be H-shaped (wraps the glass and closes with a lip), F-shaped or L-shaped. When it shrinks, a gap opens where water splashes through, usually at shower-head height.

Magnetic seal. On screens with doors that close against each other, two strips with a magnet inside that attract. If the magnet weakens or the seal comes unstuck, the door does not stay closed and opens with the water.

Profile sealing gasket. A thin strip between the fixed glass and the aluminium profile. It rarely fails, but when it does the fixed panel rattles and drips from the base of the profile.

Overlap seal. On two-door sliders, the strip that covers the gap between the two doors when closed. If it is broken, water comes out right in the middle of the screen.

To find which one has failed, shower with the door closed and look from outside for where the water appears. If it comes out at the corners of the wall profiles and not from the doors, it is not the seals: it is the silicone, and the fix is in how to seal a shower screen.

Replacing shower screen seals: how to measure them and where to buy

Shower screen seals are sold by the thickness of the glass they grip (4, 5, 6 and 8 mm are the usual ones) and by the shape of the profile. Pull off a piece of the old seal, measure the glass at the edge with a ruler or callipers and take the piece to the shop. Leroy Merlin and Bricodepot stock universal 1 and 2 metre strips for the most common profiles (drip seal with lip, H-shaped closing strip, magnetic seal) at 6 to 15 euros per metre. Ferreterías (hardware shops) with a shower screen section have more variety, and the brands (GME, Kassandra, Doccia, Roca, Duscholux) sell the exact replacement by reference on their websites.

If you cannot find the exact shape, the rule is that a universal drip seal of the correct thickness almost always works, because it only has to grip the edge and have the lip facing inwards. The vertical closing strip and the magnetic seal are more specific: if the shape does not match, the door will not close. When there is no replacement, buy the most similar clear PVC strip and test it on a short piece before cutting the whole strip.

A tip you will thank us for: buy 20 cm more than you measure. A seal cut short does not stretch, and the leftover strip will do for next time.

Cleaning and whitening shower screen seals that are still usable

If the seals are flexible and intact but yellow or with black mould, you do not need to replace them. Pull them off the glass and leave them 30 minutes in a bowl of hot water with one part bleach to ten parts water. Scrub with a toothbrush, rinse thoroughly and dry. Limescale marks come off with warm cleaning vinegar in a second 20-minute soak. Clear PVC seals recover a good part of their whiteness; the ones that have already gone rigid do not, and need replacing.

To whiten seals without removing them, a paste of bicarbonate of soda with a few drops of hydrogen peroxide, left 20 minutes and brushed off, works on surface mould. Do not use neat bleach or leave it more than half an hour: it dries out the PVC and the seal cracks within weeks. And never mix bleach with vinegar or ammonia: it gives off chlorine gas.

Common mistakes when replacing the seals

The first is buying without measuring the glass thickness. A 6 mm seal on 5 mm glass wobbles and falls off; a 5 mm seal on 6 mm glass will not go on or splits the lip. The second is cutting the seal to the exact length: PVC shrinks a little as it cools and after a month it is short. Cut 3 to 5 mm long and trim at the end if there is excess.

The third is fitting the seal on an edge with traces of limescale or old seal. It does not seat fully and comes off within days. Alcohol and limescale remover on the edge, and dry. The fourth is forcing the seal on cold: the PVC splits at the lip. A minute with a hairdryer on the strip makes it flexible and it goes on by itself. And the fifth, fitting the drip seal with the lip facing out of the shower: water goes onto the bathroom floor instead of back into the tray.

• Protect the tray with a towel if you take the door down.
• Photograph each seal in place before removing it so you remember the orientation.
• On magnetic seals, check before cutting that the two strips attract; if they repel, turn one round.

When to call a professional

Call us if you cannot find the seal with the right shape, if a heavy door has to come down to fit the drip seal, if water keeps coming out after replacing the seals (then the problem is the door adjustment or the silicone), or if the screen is more than 15 years old and the seals, rollers and silicone are all failing at once.

Our shower screen service replaces the seals and sealing profiles for the price of the seals plus the labour to adjust, and combines it with resealing in silicone (40 to 70 euros) or replacing the rollers (45 to 80 euros) in the same visit. We carry universal drip seals and closing strips for 4, 5, 6 and 8 mm glass in the van. We arrive in 20 to 45 minutes in Valencia, Alicante, Torrevieja and Benidorm. Fixed price by WhatsApp with a photo of the seal and of the glass edge, 6 months written guarantee and an invoice with IVA (VAT). More prices in how much it costs to install or repair a shower screen.

Limescale and mould: making new seals last on the coast

With the hard water of Alicante and Valencia, limescale builds up on the lip of the drip seal and hardens it. After the shower, run the squeegee over the glass and dry the bottom seal with the towel. Once a month, spray cleaning vinegar on the seals, wait 10 minutes and rinse. In bathrooms without a window, ventilate for 10 minutes after each shower so mould does not settle on the magnetic seal.

If the glass is white with limescale, the method is in how to clean a shower screen and remove limescale without scratching the glass. And if, while replacing the seals, you notice the door is stiff or has dropped, check how to fix a sliding shower screen before fitting the new seals: a badly adjusted door deforms the closing strip within a few months.