September can still be a good time to tackle exterior sealing jobs, but cooler temperatures and more unpredictable rain mean preparation matters.

Whether you’re sealing around frames, exterior joints or other suitable areas, checking the weather and preparing the surface properly can make a big difference to the finished job.

Check the Weather Before You Start

Before reaching for the sealant gun, check the conditions as well as the product instructions.

For standard silicone sealants, Soudal advises applying to a clean, dry surface and says silicone sealant should not be applied in the rain. Its general guidance also states that ambient and substrate temperatures should be above 5°C, although the exact application range depends on the individual product.

That's particularly important as we move further into autumn.

Make Sure the Surface is Ready

Good preparation starts with removing dirt, dust, grease and loose material from the area you're sealing.

If you're replacing an existing seal, remove the failed material and any remaining residue that could interfere with the new sealant.

Don't rush straight into applying a fresh bead over a poorly prepared joint. The new seal is only as good as the surface you're applying it to.

Choose a Sealant Suitable for the Job

Not every sealant is suitable for every exterior application.

Before buying, check:

• Whether it's suitable for exterior use
• Which materials it can be applied to
• Its recommended application temperature
• Whether the joint is likely to experience movement
• Whether a primer is required
• Any limitations listed by the manufacturer

For example, Soudal's Silirub AL is designed for exterior applications including perimeter sealing around wood, PVCu and aluminium window and door frames, roofline and drainage systems, and certain façade applications.

The right choice ultimately depends on what you're sealing and what it's made from.

Don't Confuse Weather Resistance With Wet Application

This is an easy mistake to make.

A sealant being resistant to rain after curing doesn't necessarily mean you can apply it to a wet surface or while it's raining.

Some hybrid products are specifically designed for application in damp or all-weather conditions, whereas standard silicone products can have different requirements. Always check the individual technical information before starting.

Get Exterior Jobs Sorted Before the Weather Turns

Early autumn gives you an opportunity to inspect exterior joints and deal with deterioration before colder and wetter conditions become more frequent.

Choose a dry day, prepare the joint properly and, most importantly, use a sealant that's actually suitable for the surfaces and application you're working on.

Browse Silicone Direct's range of exterior sealants to find an option for your next job.