Natural light in the loft — skylight, dormer or ridge raising?

What does the Bbl require for natural light?

For habitable rooms (bedroom, study):

• Minimum 10% of the floor area in transparent glass.
• Glass must provide a view of the outside (not an inner courtyard without natural light).
• For a 12 m² room, this means at least 1,2 m² of glass area.

In practice, you will want 15–20% for a truly pleasant space. A Velux M06 (78×118 cm) provides 0,92 m² of glass — just enough for a 9 m² room. For larger rooms, opt for two skylights or a dormer.

Skylight (Velux) — fast and cheap

A skylight is often the first choice for lofts. Advantages:

• Fast installation: 1 day of work per window.
• Cheap: € 800 – € 1.400 each, including installation.
• A lot of light: a window in the roof lets in 30–40% more light than a facade window of the same size.
• No planning permission required in most municipalities (if not a listed building).

Points of attention:

• Heat: without exterior sun protection, the loft becomes unlivable in July.
• Being overlooked from higher adjacent buildings is possible.
• Cleaning can be complicated — choose a model with a rotating top section.
• Rain sensitivity: high risk of dripping inside when left open. Velux Integra (auto-closes when it rains) is a nice upgrade.

Best locations: windows distribute light most evenly when positioned on the south or west side and high up in the roof plane.

Dormer — light and space

A dormer combines natural light with frontal headroom. For those who truly want to live in their loft:

• Glass area: 1,5–3 m² per dormer — immediately sufficient for 15–30 m² of habitable space.
• Headroom in front of the window: important for a desk, clothing rack or reading chair.
• Aesthetic review (welstand) for the front: often stricter than for a skylight.
• Planning permission: often permit-free at the rear, but almost always required at the front.

Costs: € 7.500 – € 16.000 per dormer. Per m² of extra living space, it is comparable to a skylight, but you gain headroom as well.

See also: Dormer costs.

Ridge window and special solutions

For specific situations:

• Velux Cabrio: a skylight that transforms into a small balcony in one motion. Beautiful for bedrooms with a view. € 3.000 – € 4.500 including installation.
• Ridge window: a window in the ridge itself, provides natural light directly from above. Suitable for modern architecture, often subject to aesthetic review.
• Skylight dome: a round/square window in a flat roof — especially for a roof extension or ridge raising with flat sections.
• Light tube / Sun Tunnel: brings light to a spot without a roof plane (e.g., a walk-in closet or landing). 30–40 cm diameter, € 600 – € 1.200.

Combine where possible: a loft with a dormer at the rear and two skylights at the front has light coming from two directions — much more soothing than light from just one corner.

Sun protection — do not forget this

Without sun protection, every loft turns into an oven in the summer. Three levels:

• Exterior sun protection (roller shutter or awning): up to 95% sun-blocking. The best solution against summer heat. € 300 – € 700 per skylight.
• Intermediate sun protection (blinds between 2 panes of glass): standard with Velux Integra. Effective, but less so than exterior options.
• Interior sun protection (roller blind): blocks people from looking in, but the heat already enters. Limited effect against the heat.

Combine: an exterior roller shutter + an interior blackout roller blind = pitch black for sleeping in.

Automatic control (sun sensor): the roller shutter closes in direct sunlight and opens in cloudy weather. Comfortable and energy-efficient.

Frequently Asked Questions

Short, honest answers to frequently asked questions.

Which orientation is best?

North = constant, soothing light without heat, great for a study. South = a lot of light and heat, better with exterior sun protection. East = morning light (bedroom), west = evening light (living room).

How many skylights do I need?

Rule of thumb: 1 Velux M06 per 9 m² of floor area. So for 18 m² you need two windows, for 27 m² three. Distribute them along the length of the room for even lighting.

Am I allowed a skylight in a protected cityscape?

Sometimes yes, provided it fits historically (small size, with glazing bars). Ask the monuments committee of your municipality beforehand.

What is the difference between Velux and Fakro?

Both are top quality. Velux is the market leader, making accessories easier to get. Fakro is often slightly cheaper with comparable specs. The practical difference is small.

How do I prevent leaks around a skylight?

A good builder + original flashing kits (Velux GIL or EDS) + a model suitable for your roof pitch. When in doubt, do a water test before finishing.

What does a Sun Tunnel do?

Brings natural light via a reflective tube to places without a roof plane — useful for a landing, closet, or bathroom without a skylight. No planning permission required, € 600–1.200 installed.

Does an electric skylight really work that much better?

Velux Integra (electric, with rain and sun sensors) is much more comfortable for high or hard-to-reach places. Additional cost € 300–500. Absolutely recommended for remote corners of the loft.

How do I combine natural light with privacy?

Skylights placed high in the roof plane (above 1,80 m) provide light without making the interior visible. For a dormer: curtains or net curtains.

Summary

For enough natural light in the loft, you choose between a skylight (fast, cheap), a dormer (light + headroom) or special solutions like Cabrio or Sun Tunnel. The Bbl minimum requirement is 10% glass area compared to the floor area — for comfort, aim for 15–20%. Exterior sun protection is not a luxury for a loft but a necessity against the summer heat. Where possible, combine light from different directions for a soothing atmosphere.