Are you looking to replace the old, weathered or damaged rubber window seals in your property, car, boat, or caravan? If so, it’s essential to understand how to correctly fit your window seals, ensuring a good weatherproof seal and the ultimate protection from the elements. This comprehensive guide will provide you with all the necessary instructions, allowing you to fit rubber window seals like a pro. 

Key Takeaways:

  • Rubber window seals are used to protect houses, cars, boats and caravans from the outdoor elements. 
  • Rubber window seals are typically manufactured from EPDM rubber due to its excellent weathering, wind, UV light and ozone resistance properties. 
  • It’s critical to choose the correct size rubber window seal to ensure a tight and weatherproof fit, this can be measured using the window size and panel thickness. 
  • To remove your old window and rubber seal, carefully pry away the filler strip before pushing the glass away from the seal. 
  • Installing a new seal requires it being cut to size, bonded with sealant and fed into the panel. 
  • To ensure a secure fit, a rubber filler strip should be installed into the last recess of the rubber window seal
  • You can browse our full catalogue of rubber window seals by visiting our website

What is a Rubber Window Seal?

A rubber window seal, also known as a claytonrite rubber seal is a flexible extrusion profile, typically manufactured from EPDM rubber and used to create a secure and airtight seal around the edges of a window. The seal is designed to fit tightly between the window and the frame, filling in any gaps or spaces between them. This prevents cold air from entering, warm air from exiting and moisture build up in the interior of a property or vehicle. 

Rubber window seals are commonly used in a wide range of applications, including residential and commercial buildings and vehicles such as cars, trucks, boats and caravans. They are available in various shapes and sizes to fit almost any type of window and can be manufactured to bespoke specifications if required. 

Why are Rubber Window Seals manufactured from EPDM?

EPDM (Ethylene Propylene Diene Monomer) is used for rubber window seal manufacturing due to its excellent weathering, wind, UV light and ozone resistance properties, making it the optimum choice for seals destined for outdoor use and exposed to the elements. Additionally, EPDM rubber offers a wide operating temperature of -50 °C to +150 °C, excellent tear and abrasion resistance, leaving you confident your rubber window seals will stand the test of time. 

What size Rubber Window Seal do you need?

Before you purchase a rubber window seal, it’s crucial to determine the exact size required, allowing for a tight fit and optimum weatherproofing. To do so, precisely measure the size of your window and panel thickness, before visiting our online store to find the correct seal. Each seal is clearly labelled with glass and panel thickness to help you choose the right profile. If you are still unsure, feel free to contact us for assistance. 

How to remove the old window 

The removal of your old window is simple, however we recommended wearing the correct PPE in case of any glass breakages. Begin by locating the ends of the filler strip from your existing rubber window seal. Use a flathead screwdriver and begin slowly prying the rubber filler strip out, working your way around the window until the strip has been removed. 

You can now remove the window by firmly pushing in the centre, this will cause the glass to come away from the existing rubber seal. Carefully remove the window and keep it safe for re-installation (if you’re installing new windows, please ensure the old glass is recycled in the correct manner). After removing the window, pull the rest of the existing rubber window seal away from the panel and clean the area of any leftover residue and dust. 

How to fit the Rubber Window Seal 

Once you have successfully removed the old rubber window seal and cleaned the area, it’s time to fit the new seal. Begin by placing the rubber window seal around the opening of the window, pressing firmly into the corners allowing you to determine the required length. Once you are happy with the length, trim the rubber seal with a square cut, leaving a small tag end (approx 30mm) used later to create a joint. 

Now remove the newly measured rubber window seal from the window and apply a small amount of silicone sealant into the panel recess, before refitting the seal in the same manner. However, this time it’s important to ensure the joint is at the top of the window. Once the seal is in place, apply another small bead of silicone sealant into the window recess, before carefully pushing the new window into the secured rubber window seal. The process of getting the lip section of the seal over the window can be fiddly, therefore we suggest using a glazing tool to carefully pry the rubber window seal lip over the window. 

How to install the Rubber Window Seal Filler Strip

Finally, to ensure a tight and waterproof fit for your window, you must install the rubber filler strip. Again, using the glazing tool from the previous step, thread the filler strip into the last recess of the rubber window seal, applying a generous amount of lubricant to facilitate installation. Avoid stretching the rubber filler strip and slowly work your way from the bottom of the window all the way around. Now cut the filler strip to the correct length, ensuring you leave a small overlap. Firmly push the overlapping section into the filler strip recess and your rubber window seal is now secure. 

Where can you buy Rubber Window Seals?

At Delta Rubber Limited we offer a comprehensive range of rubber window seals, manufactured from high-quality black 70° Shore EPDM rubber to ensure maximum durability and longevity of life. Our range includes common profile sizes to suit many standard size household, car, boat, or caravan windows. You can purchase our most popular range of rubber window seals through our easy-to-use online shop, we offer next working day delivery and prices unrivalled in the industry. 

Although comprehensive, our full range of rubber window seals are not all available online, to browse our full catalogue, download our PDF catalogue and print off images at 100% A4 format for an accurate scale representation of extrusion size. Once you have found the rubber window seal you require, contact us with the reference number for a quotation. 


Fitting new windows can be a daunting task, but if you follow these guidelines, you’ll be able to do it yourself with ease. Always remember to measure the correct size of the seal, Remove the old window carefully, secure your new window seal and work your filler strip into the channel. If you require any further assistance or have any questions please do not hesitate to contact us.