Modern Window Weather Sealing Materials

Why Material Choice Matters

Weather sealing is one of the most effective—and affordable—ways to improve energy efficiency in UK homes. By closing small gaps around windows, you can:

• Reduce draughts and heat loss.
• Improve acoustic insulation.
• Lower energy bills.
• Extend the life of timber or uPVC frames by keeping out moisture and dirt.

But not all window sealing materials perform the same. The three most widely used options today are brush pile, silicone strips, and foam tape—each with their own strengths and limitations. Choosing the right one depends on your window type, property age, and performance expectations.

Overview of Brush Pile Seals

Brush pile seals are strips of densely packed fibres (often nylon or polypropylene) fixed to a carrier. They compress against the moving parts of the window or door to form a flexible barrier.

Advantages:

• Excellent for sliding sash windows and patio doors.
• Flexible and durable—can handle frequent movement.
• Good acoustic insulation as fibres dampen vibration.
• Can be combined with a central fin for added draught resistance.

Limitations:

• Not as airtight as solid seals.
• Requires precision fitting to maintain effectiveness.
• May wear down over time in high-traffic applications.

Best Suited For:

• Sliding timber sash windows.
• uPVC or aluminium sliding patio doors.
• Period homes where discreet sealing is needed without altering the frame design.

Silicone Seal Strips: Pros & Cons

Silicone seals are continuous rubber-like extrusions designed to be fixed around window perimeters. Available in various profiles (tubes, fins, E-strips), they provide a resilient seal that compresses when the window closes.

Advantages:

• Highly durable—resists UV, moisture, and temperature extremes.
• Excellent for hinged casement and tilt-turn windows.
• Creates a very airtight seal, ideal for thermal efficiency.
• Long service life compared with foam or brush.

Limitations:

• Installation requires accuracy—if poorly fitted, the seal may distort the window closing action.
• More visible than brush pile in heritage settings.
• May increase closing resistance on lightweight frames.

Best Suited For:

• Modern uPVC and aluminium casement windows.
• Timber casements in need of improved airtightness.
• Properties aiming for maximum energy efficiency.

Foam Sealing Tape Performance

Foam sealing tape (often made from EPDM, polyurethane, or PVC) is a compressible strip with adhesive backing. It’s widely used as a quick and inexpensive DIY sealing solution.

Advantages:

• Easy to install—simply cut and stick.
• Low cost and widely available.
• Effective at filling irregular gaps where rigid seals won’t fit.
• Good short-term draught reduction.

Limitations:

• Shorter lifespan—tends to degrade with UV and moisture exposure.
• Adhesive can fail over time, especially on painted timber.
• Less durable in high-use areas where the window is opened frequently.

Best Suited For:

• Temporary draught-proofing solutions.
• Rental properties or short-term projects.
• Non-opening windows or secondary glazing.

Which Material Is Best for Your Window Type?

General Rule:

For heritage and sliding systems, brush pile is often preferred.

For modern hinged systems, silicone strips outperform.

For budget or temporary fixes, foam tape offers convenience.

Frequently Asked Questions

1. Which seal material lasts longest?
 Silicone seals generally last the longest, often 10–20 years, while brush pile lasts 5–10 years. Foam tape may only last 1–3 years before replacement is needed.

2. What’s best for timber vs uPVC windows?
 Timber sash windows work best with brush pile. For uPVC casement windows, silicone is usually the superior choice.

3. Do any seals affect how the window opens?
 Yes. Silicone strips can increase closing pressure if oversized. Brush pile has minimal impact. Foam tape can sometimes snag if applied incorrectly.

4. Can I install new seals myself?
 Foam tape and self-adhesive brush pile are DIY-friendly. Silicone gaskets may require more specialist fitting for a proper airtight finish.

Conclusion

Choosing the right window sealing material can significantly improve comfort, reduce energy bills, and extend the lifespan of your windows.

• Brush pile works best for sliding and heritage designs.
• Silicone strips are the premium option for modern airtight performance.
• Foam tape is a quick, cost-effective solution but lacks longevity.

By matching the material to your window type and project goals, you can create a weatherproofing solution that balances performance, durability, and cost.