As the weather starts to turn, September is a good time to check the seals around your windows and external doors.

Cracked, loose or missing sealant can allow draughts and moisture through gaps around frames. Fortunately, replacing failed sealant is a relatively straightforward maintenance job.

How do you know if the sealant needs replacing?

Take a walk around your windows and doors and look for:

• Cracked or split sealant
• Sealant pulling away from the frame
• Visible gaps around the perimeter
• Loose or badly deteriorated sections
• Draughts coming from around the frame

Don't automatically seal every opening you find. Window vents and other intentional ventilation shouldn't be blocked.

What sealant should you use around windows and doors?

For exterior perimeter joints, choose a sealant specifically designed for external window and door applications.

The sealant needs to cope with weather exposure and movement between the frame and surrounding building materials.

Suitable products can include neutral-cure silicone and certain hybrid polymer sealants, depending on the frame, surrounding surface and application.

Always check the manufacturer's stated substrate compatibility before applying it.

How to reseal around a window or door

1. Remove the old sealant

Carefully remove failed sealant from the joint.

Getting rid of loose material gives the new sealant a properly prepared surface to adhere to.

2. Clean the surfaces

Remove dust, dirt, grease and remaining debris.

The preparation requirements can vary between products and surfaces, so check the manufacturer's instructions before application.

3. Apply the new sealant

Cut the cartridge nozzle to suit the joint and apply a consistent bead using a sealant gun.

Work steadily along the joint rather than applying too much material and trying to remove it afterwards.

4. Tool the joint

Smooth and finish the sealant within the manufacturer's recommended working time.

A neat finish isn't only about appearance – the sealant needs to make proper contact with the sides of the joint.

5. Leave it to cure

Allow the sealant to cure according to its instructions and protect it from unsuitable conditions during application and curing.

Curing times vary between products, so always check the cartridge or technical data sheet.

What about larger gaps around a frame?

Sealant isn't designed to simply fill every large or deep cavity.

Larger installation gaps may require another product or joint construction method before the external perimeter seal is applied.

For example, expanding foam is commonly used for filling and insulating suitable gaps around mechanically fixed window and door frames.

If you're unsure how expanding foam works, read our How to Use Expanding Foam: A Simple Guide.

Get your windows and doors ready for autumn

Checking window and door seals before colder and wetter weather arrives is a simple maintenance job that's easy to overlook.

If existing sealant has cracked, separated or deteriorated, replacing it with a product that's suitable for the frame, surrounding material and exterior exposure can help create a durable, weathertight perimeter seal.

Shop Silicone Direct's window and door sealants to find the right product for your next job.