How to Apply Silicone Sealant: Expert Guide for London Homes

What Is Silicone Sealant?

Silicone sealant is a flexible, waterproof material used to seal joints and gaps between surfaces. Unlike rigid adhesives, silicone can accommodate some movement as surfaces expand, contract or flex.

It is particularly useful in bathrooms and kitchens because it is designed for areas exposed to moisture. Bathroom silicone can also contain mould-resistant additives to help it perform in damp conditions.

Different silicone products are designed for different surfaces and applications. Always check the manufacturer's instructions before use.

Can Silicone Stop Water Leaks?

Silicone can help stop water passing through gaps and joints when the seal is applied correctly.

It is commonly used around baths, shower trays and sinks. However, silicone will not fix every type of leak. If water is coming from pipework, a fitting or behind a wall, the underlying problem needs to be repaired first.

What Is Silicone Sealant Used For?

Bathroom Applications

Silicone sealant is commonly used around baths, shower trays, sinks and other bathroom fittings.

For areas exposed to regular moisture, choose a bathroom silicone that is suitable for the surface and offers mould resistance. For more advice on maintaining bathroom fixtures, see our guide to showers, taps and bathroom fittings.

A properly applied seal helps prevent water getting behind fittings and can reduce the risk of moisture damage.

Kitchen Sealing

Silicone can be used where worktops meet walls, around splashbacks and in other areas exposed to water.

Choose a product that is suitable for the materials involved and regular cleaning.

Window and Door Sealing

Suitable silicone products can also be used around window and door joints to help create a weather-resistant seal.

The product should be appropriate for the materials and the amount of movement expected.

How to Prepare a Surface for Silicone Sealant

Good preparation is one of the most important parts of applying silicone.

Clean the Surface

Remove dirt, grease, soap residue and other contamination from the joint.

On suitable non-porous surfaces, use an appropriate cleaner such as methylated spirits or white spirit, following the product instructions. Allow the surface to dry fully before applying new sealant.

Remove Old Sealant

Score along both edges of the existing sealant with a sharp utility knife. Carefully peel away the old silicone in strips where possible.

Use a scraper or suitable removal tool for any remaining material, taking care not to damage the surface underneath.

Make Sure the Area Is Dry

Silicone needs a clean, dry surface for good adhesion.

In a bathroom, use ventilation and allow the area enough time to dry after cleaning. Also check that there are no active leaks bringing moisture back into the joint.

Use Masking Tape

Masking tape can help create straight edges if you are not confident applying silicone freehand.

Place the tape parallel to the joint, leaving the required gap exposed. Smooth the silicone, then remove the tape while the sealant is still workable.

Tools and Materials Needed

For a straightforward silicone sealing job, you may need:

• Mould-resistant bathroom silicone
• A sealant gun
• A sharp utility knife
• A smoothing tool
• A suitable surface cleaner
• Clean cloths
• Masking tape

Using the right tools makes it easier to apply an even bead and achieve a neat finish.

How to Apply Silicone Sealant: Step-by-Step

Step 1: Cut the Nozzle

Cut the cartridge nozzle to the size required for the joint. The opening should match the bead size you need.

Test the flow on a scrap surface first if you are unsure.

Step 2: Load the Cartridge

Place the silicone cartridge into the sealant gun and make sure it is seated correctly.

Squeeze the trigger gently until the plunger reaches the base of the cartridge.

Step 3: Apply the Sealant

If you are resealing a bath, filling the bath with water before applying the silicone can account for movement when the bath is in use.

Hold the gun at roughly a 90-degree angle to the joint. Apply steady pressure while moving the nozzle along the joint at a consistent speed.

Keep the nozzle in contact with both sides of the joint where possible so the silicone fills the gap evenly.

Step 4: Smooth the Sealant

Smooth the bead immediately after application using a suitable smoothing tool.

Work along the joint in one steady movement and remove excess sealant as you go. Aim for a smooth, slightly raised finish that allows water to run away from the joint.

Step 5: Remove Masking Tape

If masking tape was used, remove it while the silicone is still workable.

Pull the tape away carefully so you do not disturb the fresh bead.

Best Practices for a Professional Finish

Use Mould-Resistant Silicone

For showers, baths and other damp areas, choose silicone designed for bathrooms and mould resistance.

Check that the product is suitable for the materials and application before using it.

Ensure Good Ventilation

Keep the room well ventilated while the silicone cures. Use an extractor fan or open a window where appropriate.

Follow the manufacturer's curing instructions before exposing the new seal to water.

Inspect Seals Regularly

Check bathroom seals for cracks, mould, gaps or peeling.

Small defects are easier to deal with before water gets behind the seal.

Avoid Harsh Cleaning Products

Some strong cleaning products can affect silicone over time.

Use products suitable for the sealed surface and follow the silicone manufacturer's recommendations.

Where Not to Use Silicone Sealant

Silicone is not suitable for every surface or application.

• Painted surfaces may have poor adhesion, and removing old silicone can damage the paint.
• Greasy or contaminated surfaces will prevent good adhesion.
• Aquariums require silicone specifically labelled as aquarium-safe.
• High-pressure joints require a product designed for that level of stress.
• Some porous materials may require a different sealant or additional preparation.

Always check the product label before applying silicone to an unfamiliar material.

When to Get Professional Help

DIY silicone work can be suitable for straightforward resealing, but some jobs are less simple.

If a seal keeps failing, water is getting behind a bath or shower, or the source of a leak is unclear, replacing the silicone alone may not solve the problem.

Serviceteam provides property maintenance and bathroom repair services across London. If a failed seal has allowed water into your shower area, our team can also help with professional shower repairs in London. If you need help with a leaking shower, damaged seal or persistent water ingress, a professional can identify the underlying issue and carry out the necessary repair.

Frequently Asked Questions - (FAQs)

How do you clean silicone sealant?

Use warm water and a mild detergent for routine cleaning. Avoid products that may damage the silicone or surrounding surface.

If mould or staining has become established, cleaning may not restore the seal. The old silicone may need to be removed and replaced.

How long does silicone sealant smell?

The smell can remain for around 24 to 48 hours, depending on the product and ventilation.

Keep the room well ventilated and follow the manufacturer's instructions.

How long does silicone sealant take to cure?

Many silicone sealants take around 24 hours to cure, although curing times vary between products.

Always check the cartridge or manufacturer's instructions before using the sealed area.

Is silicone sealant waterproof?

Once fully cured, suitable silicone sealant provides a waterproof seal. It is commonly used around baths, showers, sinks and other areas exposed to moisture.

The surface needs to be prepared properly, and the silicone must be applied and cured according to the product instructions.

Can silicone sealant be painted over?

Generally, silicone is not suitable for painting because most paints do not adhere well to it.

If you need a paintable seal, choose a product specifically designed for that purpose.

Need help with a failed bathroom seal or a leaking shower? Serviceteam can inspect the problem and carry out the necessary repair or resealing work across London. Get in touch to arrange a professional service.