Blackout blind for Velux windows: the roof window guide

Why attic bedrooms are the hardest to treat

An attic bedroom combines problems that lower floors do not have:

• The roof window receives sunlight vertically: a wall window receives radiation at an oblique angle. A roof window receives almost perpendicular radiation, especially in summer when the sun is high. The solar energy captured per m² is 2 to 3 times higher.
• Hot air rises and accumulates under the roof: by natural convection, the hottest air in the dwelling concentrates under the eaves. In summer, the temperature at ceiling level can exceed the floor temperature of the same floor by 5 to 8 °C.
• The roof heats up and radiates heat: the roof absorbs solar radiation all day and radiates heat in the evening. Even after sunset, the room remains hot as the roof continues to radiate.
• Light enters as early as 5:30 am in summer: a roof window has no obstruction (no building opposite, no trees). Light intensity reaches 10,000 to 50,000 lux from 6 am.

Result: attic bedrooms are the hottest in summer (35 °C and above in the evening) and the brightest in the morning. Blackout and thermal protection are not a luxury; they are a condition for sleeping.

Two types of attic windows, two different solutions

Most attic bedrooms have two types of windows, and each requires a tailored solution:

Important note: on a sloped roof window, a curtain held only at the top pulls away from the glass. The fabric falls forward under gravity. It therefore needs a fixing at the top and one at the bottom, holding the panel along the slope. The integrated blind meets the same need differently, through its side guides. Vertical windows (dormers, gables) are treated like any wall window: a curtain on a rod. When ordering, the rod pocket is the recommended heading: it is the one that best takes a rod at each end. We do not offer a specific seam for the bottom, and that is no obstacle: several attachment systems will hold the lower edge.

Solution for sloped roof windows: integrated blind

Integrated blackout blind (Velux, Roto, Fakro)

The manufacturer's blackout blind is fixed directly into the roof window frame, with side guides that keep the fabric flat against the glass whatever the inclination. Those side guides remove light leaks along the sides.

Advantages: perfect fit to the frame, no lateral light leakage thanks to the guides, cord or remote control operation, integrated and discreet aesthetics.

Limitations:

• Thin fabric (100 to 200 g/m²): blocks light but does not insulate from heat. In summer, solar radiation heats the thin fabric, which radiates heat into the room. Blackout is good, thermal insulation is almost nonexistent.
• Fragile mechanism: the spring or cord is the weak point. Lifespan of 5 to 8 years, repair sometimes impossible (parts unavailable for older models).
• Price: 80 to 200 euros for manual version, 200 to 400 euros for motorized version. Price quickly increases with options.
• No acoustic performance: the thin fabric does not reduce the noise of rain on the Velux (50 to 70 dB, very annoying at night).

Exterior sunshade blind

The sunshade is installed on the exterior of the roof window and blocks solar radiation before it reaches the glass. This is the most effective solution against heat because it prevents the greenhouse effect (heat never penetrates between the glass and the room).

Advantages: blocks 75 to 90% of solar heat before the glass. Significant reduction in temperature in attic rooms in summer.

Limitations: does not block 100% of light (it is a dimming blind, 80-90%, not a blackout). Exposure to weather (reduced lifespan). Price: 150 to 350 euros.

Solar film on the Velux glass

A solar film adhered directly to the glass rejects 40 to 70% of solar radiation. It is an effective complement to the integrated blind: the film permanently deals with heat (even when the blind is open), and the blind deals with light when you close it.

Cost: 15 to 50 euros per window. Limitation: reduces light all year round (including in winter when natural light is welcome). May void the glazing warranty on some models.

Solution for vertical attic windows: custom-made curtain

Dormer windows, gables, mansard windows, and wall windows in attics are treated like any classic wall window. This is where the custom-made Kurtens curtain is perfectly suited:

• 100% blackout*: the 620 g/m² multi-layer fabric blocks all light, including sunrise at 5:30 am in summer. Zero halo on the edges thanks to custom sizing (15-20 cm lateral overlap).
• Thermal insulation up to 7 °C*: the curtain creates an air gap of 5 to 10 cm between the glass and the fabric, slowing down thermal exchange. On an exposed west-facing gable window (overheating at the end of the day), the effect is immediate.
• 22 dB sound attenuation*: reduces external noise entering through vertical windows (traffic if the room is on an upper floor, neighborhood).

Custom-made Kurtens blackout curtains are manufactured to the exact dimensions of your dormer or gable windows, to the nearest centimeter, depending on the combination of width and height. For correct measurement, consult the size guide.

Comparison of solutions by window type

The optimal combination for an attic bedroom

An attic bedroom often has both a Velux and a vertical window (dormer or gable). The optimal combination treats each window with the appropriate solution:

1. On the Velux: solar film + integrated blackout blind. The film blocks 40-70% of heat permanently (even with the blind open). The blind blocks light when you sleep or nap. Cost: 95 to 250 euros.
2. On the vertical window: custom-made Kurtens thermal blackout curtain. Blocks 100% of light*, insulates against cold/heat (7 °C*), and reduces noise (22 dB*). Cost: 80 to 350 euros.
3. Night ventilation: open the Velux at night (hot air exits through the top) and the vertical window (cool air enters through the bottom). This natural draft is particularly effective in attics because the height difference between the two windows creates an air current. Free.

This combination keeps an attic bedroom 8 to 12 °C below what it would be without protection, for a total investment of 175 to 600 euros. For more information on anti-heat solutions, consult our article bedroom too hot in summer: 5 solutions.

Rain noise on a Velux: what to do?

Rain noise on a roof window is a specific problem for attics. The impact of raindrops on the sloped glass can reach 50 to 70 dB, enough to wake a sleeper (WHO recommends less than 30 dB for sleep).

The integrated blind does not help: its thin fabric (100-200 g/m²) only attenuates 0 to 3 dB of rain noise.

The Kurtens curtain on the vertical window helps indirectly: it reduces the overall ambient noise in the room by 22 dB* by blocking noises entering through the vertical window (traffic, neighborhood). When background noise decreases, rain noise seems louder, but the total sound level in the room is lower.

For rain noise on the Velux itself: the most effective solution is an exterior roller shutter (blocks noise before the glass, 10-15 dB reduction). If a shutter is not possible, an exterior sunshade blind made of thick fabric partially dampens the impact of drops (5-8 dB).

*Data from tests conducted under optimal conditions.

Need to close off a wardrobe or storage space under the eaves? Read Sloped ceiling curtain: close off your wardrobe made to measure.

Frequently asked questions