How to seal a shower screen with silicone so it stops leaking

What you need

• Craft knife with a new blade and a plastic scraper
• Silicone gun
• Silicone profiling tool, or a finger and a cup of soapy water
• Hairdryer for damp corners
• Kitchen roll and rags
• Neutral sanitary anti-mould silicone, clear or white (Pattex Baño Sano, Ceys Baño y Cocina, Sika Sanisil, 6 to 10 euros)
• Silicone remover gel (Pattex or Ceys, 6 to 8 euros)
• Cleaning alcohol
• 19 mm masking tape
• Cleaning vinegar for the limescale on the profiles

Step by step

1. 1

   Cut out and pull off the old silicone

   Run the craft knife along both faces of the bead, parallel to the profile and the tiles, without digging into the glass. Pull the bead: it should come off in long strips. Scrape off what is left with the plastic scraper, never with metal on the profile or the tray.

2. 2

   Remove the residue with silicone remover

   Apply the remover gel to the stuck-on residue, wait the time stated on the pack (15 to 30 minutes) and scrape again. Repeat if needed. Check with a fingernail that no film is left: new silicone will not bond to old.

3. 3

   Clean, degrease and dry for 24 hours

   Remove the limescale from the profiles with vinegar, rinse and wipe alcohol along the whole joint with kitchen roll. Leave the shower unused for 24 hours; just before sealing, dry the corners with the hairdryer.

4. 4

   Mark out the joint with masking tape

   Stick tape either side of each joint leaving a 3 to 5 mm gap between the two strips. Do it along the whole outside run (wall profiles and bottom profile) and down the inside verticals of the wall profiles.

5. 5

   Apply the bead on the outside

   Cut the nozzle at 45 degrees with a 3 or 4 mm opening. With the gun angled and steady pressure, run along the joint without stopping, from top to bottom on the verticals and from one end to the other on the bottom profile. Fill the corners well, which is where most water gets out.

6. 6

   Seal the inside verticals and leave the bottom profile clear

   Inside the shower, apply a thin bead only on the vertical joint between the wall profile and the tiles. Do not put silicone in the joint between the bottom profile and the tray on the inside, and do not block the drainage holes.

7. 7

   Smooth and remove the tape

   Dip your finger or the tool in soapy water and go over each bead once with light, steady pressure. Pull the masking tape off straight away, at an angle away from the joint, before the silicone skins over.

8. 8

   Leave to cure for 24 hours

   Ventilate the bathroom and do not use the shower for 24 hours. The next day, take a test shower and check the bathroom floor with dry paper at the corners of the profiles.

Why water gets past the shower screen

Cracked or peeling silicone. Bathroom silicone lasts 3 to 6 years. With limescale and cleaning products it hardens, cracks and separates from the profile or the tiles. Water gets in through the crack and appears on the bathroom floor right at the corner of the wall profile. It is the most common cause and the one this guide fixes.

The bottom profile sealed on the inside. Someone, with the best of intentions, sealed the whole inside of the screen, including the bottom profile. The water that gets into the profiles can no longer drain back to the tray, so it builds up inside, grows black mould and eventually finds its way out at the weakest point. The fix is to remove that inside silicone.

Worn door seals and drip strips. If the water is coming out through the joint between the two doors or under the door, it is not the silicone: it is the rubber seals. They are hard, shrunk or split and need replacing; we explain it in how to replace shower screen seals.

A door out of alignment or a profile pulling away. A door that is leaning leaves a gap that water splashes through. It is adjusted on the eccentric rollers; if the wall profile has come away, it has to be levelled and resealed. The adjustment is in how to fix a sliding shower screen.

A tray with no fall or a slow drain. If water pools in the tray and rises above the bottom profile, it will come out anywhere it can. Check the tray empties properly; a waste full of hair and limescale is slow to swallow and is behind many false shower screen leaks, see how to unblock a shower drain.

Where to seal a shower screen with silicone and where not to

The rule the manufacturers use (GME, Kassandra, Roca, Duscholux) is the same: outside, everything; inside, only the verticals. On the outside of the shower you seal the joint between each wall profile and the tiles for its full height, and the joint between the bottom profile and the tray for its full length, corners included. On the inside you seal only the vertical joint between the wall profile and the tiles, so that water running down the wall does not get behind the profile.

What you do not seal is the inside of the bottom profile, that is, the joint between the bottom profile and the tray on the shower side. The profiles are designed so that water getting in through the rollers and the joints drains back to the tray through that gap. If your screen has drainage holes in the bottom profile, leave those clear too.

There is one exception: fixed panel screens with no bottom profile (walk-in type) and screens on an extra-flat tray with no upstand. There the glass or the profile sits directly on the tray and is sealed on both sides, because there is no channel to drain. Check the manufacturer's instructions; they are on their website under the reference on the sticker on the profile.

Which silicone to buy for the shower screen

Neutral, sanitary and anti-mould silicone. Neutral means it does not give off acetic acid as it cures: the acetic type (the one that smells of vinegar) attacks anodised aluminium, steel and marble, and loses its grip on shower screen profiles within a few years. Sanitary or bathroom grade means it contains a fungicide against black mould. Brands you will find in Leroy Merlin, Bricodepot or the local ferretería (hardware shop): Pattex Baño Sano, Ceys Baño y Cocina, Sika Sanisil, Soudal Silirub 2S, Quilosa Orbasil.

Clear for chrome or silver profiles and for glass; white for white profiles and for joints against white tiles. One 280 ml tube does a front screen with some to spare. You also need a silicone remover gel (Pattex or Ceys, 6 to 8 euros) for the remains of the old bead, cleaning alcohol and 19 mm masking tape.

Common mistakes when sealing a shower screen

The first is sealing over the old silicone or over remains of it. New silicone does not bond to old silicone or to mould: you have to get down to a clean profile and clean tiles. The second is sealing while it is damp. Silicone will not stick to wet surfaces; 24 hours without using the shower before applying, and a hairdryer on the corners if needed.

The third is cutting the nozzle too big and laying a fat bead that then gets smoothed with a mess of strokes. Nozzle cut at 45 degrees with a 3 or 4 mm opening, a thin continuous bead, and smoothed in a single pass with a finger dipped in soapy water or a silicone profiling tool. The fourth is smoothing without masking tape: you get a wide, dirty smear either side that yellows within a year.

And the fifth, using the shower a few hours later. Neutral silicone skins over in 20 minutes but needs 24 hours to cure right through; get water on it too soon and it lifts underneath and you start again.

• Ventilate the bathroom while you apply it and during curing.
• Store the open tube with a nail in the nozzle; it keeps for a month for touch-ups.
• Do not use silicone to fix loose profiles: that is a job for wall plugs and screws.

When to call a professional

Call us if you have already resealed and water still gets out, if the wall profile moves, if there is black mould inside the profiles that will not come out, if the screen is over 2 metres or heavy fixed glass, if the tray has sunk or has no fall, or if you simply do not have 48 hours without a shower to do it calmly.

Our shower screen service does a complete reseal with neutral anti-mould silicone for 40 to 70 euros, including stripping the old silicone, cleaning off the mould and adjusting the doors if needed. If the seals are worn we replace them on the same visit for the price of the seals. If the screen is beyond repair, fitting a new one costs 90 to 140 euros and removing the old one 50 to 65 euros. We arrive in 20 to 45 minutes in Valencia, Alicante, Torrevieja and Benidorm. Fixed price by WhatsApp from a photo, 6 months written guarantee and an invoice with IVA (VAT). More prices in how much it costs to fit or repair a shower screen. For the silicone around the rest of the bathroom (bath, basin, worktop), that is a job for our small building works and repairs service.

Mould and limescale on silicone: tips for the coast

In bathrooms with no window, common in flats in Benidorm, Torrevieja or the centre of Alicante, the silicone on the shower screen goes black with mould within a year. Ventilate for 10 minutes after every shower, run a squeegee over the glass and dry the silicone on the bottom profile with the towel. Once a month, spray cleaning vinegar on the silicone, leave it 15 minutes and rinse: it holds back limescale and mould without damaging it.

Never clean silicone with neat bleach or a scouring pad: bleach dries the silicone out and opens cracks, and the scourer lifts it. If it is already black on the inside, no cleaner will bring it back: it has to be replaced. And if it is the glass that is white with limescale, the method is in how to clean a shower screen and remove limescale.