How to choose the appropriate PU foam for door and window installation?

What Is PU Foam?

Polyurethane (PU) foam, a polymer formed by reacting isocyanates and polyols, is a versatile material widely used in construction. For door and window installation, it acts as a sealant, insulator, and adhesive—expanding to fill gaps, blocking heat transfer, and bonding frames to substrates like concrete or wood. Its closed-cell structure delivers superior thermal insulation compared to alternatives like mineral wool, making it a top choice for energy efficiency.

Common Types of PU Foam for Doors & Windows

Rigid PU Foam: The most suitable for installations, it has a dense closed-cell structure with low thermal conductivity (as low as 0.018 W/(m·K)). It resists moisture, maintains shape, and withstands temperature extremes (-50℃ to +80℃), ideal for sealing exterior gaps.

Flexible PU Foam: An open-cell variant better for sound absorption than structural sealing. It’s too soft for supporting window frames but works for interior gaps in non-weather-exposed areas.

Fiberglass-Reinforced PU Foam: Used in high-performance doors and windows frames, it adds structural strength while retaining insulation properties. Suppliers like Amcon Foam offer this for energy-efficient builds.

One-Component PU Foam: Ready-to-use (moisture-curing) with straw or gun applicators—perfect for DIY and professional installs alike.

How to Choose the Best PU Foam？

1. Prioritize Installation-Specific Traits

The best PU foam for doors/windows balances flexibility and strength. Look for:

Thermal insulation: Aim for values ≤0.04 mw/m·K to meet energy standards.

Flexibility: It must compensate for frame movement (critical per RAL installation guides).

Adhesion: Bonds to PVC, metal, and wood (avoid products failing on PP/PE).

2. Lotfix - PU Foam Suppliers

LOTFIX, a one-stop sealants and adhesives solution provider in China, which is mainly producing and supplying various sealing and bonding products, including silicone sealant, PU (polyurethane) foam, super glue and other sealants. Specializes in high-performance products, delivering innovative bonding solutions for construction, automotive, and manufacturing industries.

3. Match with the Right Application Tool

Gun-type PU foam requires a high-quality foam gun for precise application. Trust manufacturers like Shandong Ju Huan, which offers 3-year warranties on metal guns—ensuring even dispensing and less waste. Avoid cheap plastic guns that clog easily.

Final Tip

For renovations or uneven substrates, prioritize gun-applied rigid foam from reputable suppliers. Pair it with a durable foam gun, and you’ll get a long-lasting, energy-efficient seal that meets professional standards.