Tetto 40 Heat Reducing Film for Roof Windows

Tetto 40 Exterior Solar Window Film for Roof Windows

Tetto 40 Lite Solar is an exterior solar window film designed for roof windows and other sloped glazing. It is intended for sunny attic rooms where angled glass receives strong solar exposure and can cause the interior to heat up faster than vertical windows.

The film helps reduce solar heat entering through the glass, reduces glare and blocks most UV radiation. It is installed on the exterior side of the pane, so part of the solar energy is managed before it passes into the glazing unit.

How Does Tetto 40 Work?

Tetto 40 uses a metal oxide coating that reflects and partially absorbs solar radiation. Exterior installation is important because it helps reduce the amount of solar energy reaching and heating the glass.

• Solar heat is reduced before it strongly affects the glass,
• secondary heat emission into the room is limited,
• the room heats up more slowly during the sunniest hours.

Light transmission of around 40% means that a significant amount of daylight still enters the room, while glare and excessive heat gain are reduced. In practice, this helps improve comfort in attic rooms during spring and summer.

Why Do Roof Windows Need a Different Film?

A roof window works in more demanding conditions than a vertical window because it is positioned at an angle and is more directly exposed to sun, rain and changing weather.

• It receives stronger direct sunlight,
• it heats up more intensively in summer,
• it is more exposed to rain, snow, hail and moisture,
• it is more affected by long-term UV exposure.

Tetto 40 is designed for this type of demanding installation. It has increased weather resistance and greater material flexibility, which supports application on sloped glass and helps the film work with temperature-related glass movement.

Recommended Applications

Tetto 40 roof window film is suitable for:

• residential attic rooms,
• bedrooms and children’s rooms with roof windows,
• offices and studios on top floors,
• rooms that overheat in the summer season,
• buildings where exterior roller shutters are not possible or not preferred.

The film reduces glare, which is useful when working at a computer, watching TV or resting during the day. UV reduction also helps slow down the fading of floors, furniture and textiles exposed to sunlight.

Thermal Comfort and Air Conditioning Load

By reducing solar heat gain through the roof window, the film can help lower the load on air conditioning or mechanical ventilation. This means rooms may heat up more slowly on sunny days and it may be easier to maintain a comfortable temperature.

How Is Tetto 40 Different from Standard Films for Vertical Windows?

Compared with standard exterior solar window films for vertical windows, Tetto 40 is designed specifically for the conditions found on sloped glazing.

• It has increased resistance to radiation and precipitation,
• it is more flexible, which supports installation on sloped glass,
• it has a subtle anthracite shade with a limited reflective effect,
• it is optimised for work in high temperatures.

FAQ – Tetto 40 Roof Window Film

What is the expected service life of Tetto roof window film?

The service life depends on many factors, especially the angle of the roof window in relation to the sun. The greater the angle and exposure, the shorter the expected service life may be. At an angle of 45 degrees, the service life of Tetto film can be assumed at around 5 years. With a smaller angle, the service life can be longer.

Other factors also matter, including salty air in coastal areas, air pollution, nearby factories, landfills, waste incinerators, highways and aggressive weather conditions such as strong winds or hail.

Should roof window film be protected after installation?

Because the film is more exposed to moisture and atmospheric deposits on sloped glass, the film edges should be protected, for example with neutral silicone or another method that does not interfere with the film structure.

Can I choose a roof window film that keeps all the light but blocks heat?

Light waves and heat-related solar energy are connected, so without reducing some light it is difficult to achieve a noticeable heat reduction effect. Tetto 40 is designed as a balanced solution: it provides strong heat reduction while still maintaining a significant level of light transmission.

What can be used on a roof window to reduce sunlight?

Possible solutions include:

1. blinds,
2. shutters,
3. awnings,
4. roof window mats,
5. thermal mats for roof windows.

Tetto 40 works directly on the glass as an exterior solar window film, helping reduce solar heat gain through roof windows while maintaining daylight.