FAQ

Install

Is installation of VELUX Skylights possible at any roof pitch?

VELUX skylights/roof windows (VSE, VS,GGL,GGU and FS) can be installed at 15° - 90° . For installation in roofs below 15° these products need to be pitched up and installed with a custom made flashing.

VELUX Low Pitch Skylights , FCM and VCM can be installed from 0 degrees to 60°.

Can I operate a VELUX Skylight electrically?

Yes. VELUX has the first complete " plug & play " electric opening skylight – VSE. The VSE electric opening skylight comes with a complete electrical system for easy and fast installation.

The Pivoting Roof Windows (GGL or GGU) can also be electrified by installing the necessary components (window opener, control unit,rain sensors,  infrared receiver).

Go to VELUX VSE Electric Opening Skylight
Go to GGL/GGU Electrified Pivoting Roof Windows 

Can I install a VELUX Blind myself?

Yes. VELUX blinds are designed to fit VELUX Skylights and can be installed in a matter of few minutes. Models VSE/VS/GGL/GGU/FS have the Pick & Click system which makes the installation even easier. Make sure you follow the installation instructions provided to assure perfect fit!

How close to the ridge can I fit a VELUX unit?

We suggest no closer than 400mm to allow the top flashing to be clear of the ridge cap and to allow adequate fixing for the roofing material above the skylight without puncturing the VELUX flashing. If the unit is closer than 400mm to the ridge the flashing could run under the ridge capping as long as it is not nailed or screwed through.

Can I install a VELUX Skylight myself?

No. VELUX Skylights are products which we recommend are installed by a professional installer. Working with roof construction is a job for a skilled carpenter, not a do-it-yourself job. If you cant find a Builder we can help you.

Installer locator

Is installation the same regardless of the roofing material?

No, you have to be aware of the different kinds of roof materials.

How do I measure my roof pitch?

The most accurate method is by using a pitch-gauge placed on the roof itself. This gives an accurate reading of the degree of roof slope (a pitch-gauge can be purchased at local building supply stores). The alternative is to measure the rise over the run.

What size skylight do I need for adequate natural ventilation?

Approved Document G4: Ventilation states that the natural ventilation requirement is 5% of floor area. To give the approximate room size for which the unit will be adequate as the only ventilation source multiply the ventilation areas in the table below by 20.

See the Technical data

What size skylight do I need for adequate natural light?

Approved Document G7: Natural Light states that the daylight area should equate to minimum 10% of the floor area. NOTE: 10% of floor area gives 30 lux for 75% of the standard year. Typical lux requirements by area/usage are shown below:

Hallways 30 lux
Relaxation/Conversation 30 lux
Toilet/Washroom 50 lux
Dining 50 lux
Dressing/Grooming 300 lux
Reading/Deskwork 300 lux
Handcrafts/Hobbies 300 – 1000 lux (standard, difficult, critical tasks)

You can see how much light each product gives you in the table below. The figures shown represent the minimum 10%.

Go to Technical data

What dimensions for the light shaft?

The length of shaft is determined by the position of the skylight in the roof - the longer the shaft the bigger the skylight should be to allow for sufficient light and ease of construction. The lightshaft should be splayed out from the bottom and top of the skylight. At the top of skylight the shaft is typically returned to the ceiling at a right angle to the roof pitch (depending on roof pitch and length of shaft) the sides of the shaft are typically vertical as splayed sides can interfere with the trusses.

How close together can VELUX units be fitted?

If using EDW flashing – no closer than 600mm to ensure that flashings do not touch
If using EKW combi-flashing or EDL flashing a gap of 100mm is required between external frames.

Suntunnel

Will the ceiling diffuser get dirty?

The diffuser is tightly secured with a gasket. If for some reason it is necessary to clean the diffuser pan, the diffuser can easily be loosened and the dirt removed.

Can end-users install the VELUX Sun tunnel themselves?

It is always advisable to have a professional install any VELUX product.

What is the big difference between this VELUX Sun tunnel and the competitors?

The VELUX Sun Tunnel has a low profile design, and blends with your roofline. No domes or bubbles on your roofline result in an aesthetically pleasing look. We also provide the only service for calculating the amount of daylight a Sun Tunnel will give you, based on exact room dimensions, orientation and location. 

Calculate your Daylight 

Our VELUX Sun tunnel has an integrated frame and flashing, which means that you do not have to buy a separate flashing - everything is included in one box.

Can the VELUX Sun tunnel be installed in flat roofs?

No, the VELUX Sun tunnel can be installed on roof picthes from 15⁰ to 60⁰ inclusive. For flat roofs we recommend the use of a Low Pitch Skylight.  

Can the VELUX Sun tunnel be installed in a raking/sloping ceiling?

The VELUX Sun Tunnel is designed mainly for installations where there is a larger distance between the ceiling and the roof. The gap between the ceiling and the roof needs to be atleast 400mm for installation of the VELUX Sun Tunnel.

How do I get as much light as possible from my VELUX Sun tunnel?

Facing north is always best (in the Southern Hemisphere). Keep the flexible tunnel as short and straight as possible. Of course the time of the day, season of the year, position of the sun and the longitude/latitude will also influence the light output. Even the colour of the walls in the room will affect the perception of light. The Rigid Sun Tunnel gives you 3 times more light than the Flexible as it has a highly reflective surface.

You can also calculate how much light each will give you depending on your exact situation - size of room, height of celing, position etc., by using our Daylight Calculator.

Go to Daylight calculator

What is the maximum length of a VELUX Sun tunnel?

The standard VELUX Sun tunnel with a rigid tunnel can be extended with ZTR extension pieces to a maximum of 6 metres.

How is the light output from the flat glass compared to the acrylic domes?

Testing shows that the difference is very small. The major advantage of the glass is that it will not fade and be scratched over time as the domes, which reduces the efficiency substantially.

Should the VELUX Sun tunnel be insulated?

In general, insulation is not necessary. However, in very cold climates it is recommended because of the big difference in temperature within the tunnel and in the loft.

Will the glass withstand heavy hailstorms?

The glass is 4 mm toughened glass which is very strong.

How large a room can a VELUX Sun tunnel light?

A room or hallway of 9-10 m² would be properly lit. You can use our Daylight calculator to find out about your specific situation, room size, ceiling height etc.

Go to Daylight calculator

What is the size of the VELUX Sun tunnel?

The VELUX Sun Tunnel diameter is 350mm. The dimension of the square sash visible on the roof is 470mm x 470mm. Please note that the roofing material will nearly cover up the flashing and only a little more than the sash will be visible.

In what kind of rooms do you recommend the installation of a VELUX Sun tunnel?

– interior bathrooms/toilets
– hallways
– utility rooms/laundry rooms/storage rooms
– other (small/long) dark places

What kinds of materials are used for the VELUX Sun tunnel?

Frame and flashing are made from PU (polyurethane). The flashing features a lead-free bottom section
Sash = ASA (UV-stabilised ABS plastic)
Glass unit = 4 mm toughened, insulating glass unit
Diffuser = ABS
Tunnel = highly reflective metallised polyester for the flexible version and aluminium with a layer of silver for the rigid version

What about technical values, r-value etc?

No official, international standards exist for evaluating the technical performance of "tubular daylighting devices", and they should not be compared with "traditional window values". However, because of the demand VELUX has calculated and measured various values which appear from the Technical Specifications section. Be aware not to make direct comparisons with competitors due to the lack of standards.

Go to Technical data

What about condensation?

Thorough testing has proved that condensation does not pose any problems. The system is closed.

How is the diffuser removed?

Snap off the ceiling trim ring and release it. Then loosen the snap rings to unlock the diffuser pan. No tools are needed.

Can the light of the diffuser be blocked?

No, this is one of the reasons why we do not recommend installing a VELUX Sun tunnel in the bedroom as you will be able to perceive even the moonlight .

Is leaking a problem?

The VELUX Sun tunnel is installed by the well-known VELUX installation technique which ensures a watertight connection to the roof. Excellent results in our wind tunnel test facilities prove water tightness up to 600 Pa (class 9A) in 15° and 60° roof pitches in compliance with EN 12208.

What about maintenance?

The frame/flashing part is made of maintenance-free polyurethane (PU). The glass pane will automatically be cleaned by rain due to the special stay-clean coating on the glass. Compared to acrylic domes, which will most likely fade and be scratched over the years, the toughened glass in the VELUX Sun tunnel will remain nice and clear.

How long does it take to install a VELUX Sun tunnel?

Usually it will take 2-5 hours depending on the roofing material and any obstacles in the loft.