How to choose rubber seals for windows

Choosing the right rubber seal for windows requires assessing four key factors: measurements, material, type, and environment. Correct selection ensures energy efficiency, reduces noise, and prevents moisture infiltration. 
1. Measure the Gaps Accurately 
Precise measurement is crucial for a tight, effective seal. 
Measure the gap width: Determine the size of the gap between the window sash and the frame using a tape measure.
For example, gaps between 1-2mm may require a seal width of 3.5-4.0mm, while larger gaps (3-4mm) need a wider seal (6.0-7.0mm). The seal should compress just enough to close the gap without affecting the window's operation.
Measure the existing seal (if replacing): If possible, remove a small section of the old seal and measure its width and profile shape to match it with a replacement.
Measure the glass thickness: For glazing gaskets (seals that hold the glass in the frame), measure the glass thickness to ensure the new seal's channel fits snugly. 
2. Select the Right Material
The operating environment dictates the best material choice. 

EPDM Excellent resistance to UV, aging, ozone, and extreme weather; durable and flexible in cold temperatures. Ideal for outdoor, exterior-facing windows in all climates.
Silicone Superior heat resistance, very flexible, durable, and resists UV rays well; maintains flexibility in harsh conditions. Excellent for demanding conditions or applications near high heat sources.
PVC Cost-effective and available in various colors; good chemical resistance. Suitable for indoor or light-duty applications; can become brittle in extreme cold or warp in high heat over time.
Neoprene All-around choice with good resistance to heat, fire, UV, water, and oil. Versatile for various applications where multiple resistances are needed.
3. Choose the Correct Type/Profile
Different window designs require specific seal profiles. 
Compression Seals: Used in casement or hinged windows; compress to form a tight seal.
Bulb Seals: Often used in sliding windows to offer excellent insulation.
Wedge Gaskets: Secure the glass within the frame (common in aluminum or uPVC windows).
Foam Seals (D, P, E, I-types): Self-adhesive and ideal for smaller, irregular gaps; easy to install. 
4. Installation and Maintenance
Ease of Installation: Consider if you need a simple self-adhesive seal or one that requires a more involved installation process.