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8 tips for choosing a roof window


Here are a few tips and some information for you when considering installing roof windows.


1. Check the roof pitch

1. Check the Roof Pitch... Our roof windows are suitable for a roof pitch of 15°- 90°. If your roof has a lower pitch, there is no guarantee your roof window can be installed properly. 
Roof Pitch continued... The roof pitch is really important to ensure a watertight roof window. If the water cannot drain, it will come inside and cause leakage. Below a 15° pitch makes it possible for driving rain to cause water ingress under the hood section.




2. Check the roofing material

 2. Please Check the Roofing Material Our flashings are compatible with all standard roofing materials. The only exception is the standing seam as used in some metal roof profiles.





3. Check the roof window height

 3.  Please Check the Floor to Window Height We suggest installing our roof windows at between 90-130 cm. With the bottom handle roof windows, you can install a higher window and gain extra light (compared with top-flap windows, where the usability is limited due to the high “flap”). 


Out of reach

Please note you can install it higher, but then you might need an electric opener to operate it.

4. Check the roof pitch to plan your roof windows

 4. Check the Roof Pitch to Plan your Windows If you have a lower roof pitch of around 30-55°, we suggest you install a high-pivot roof window. With a high pivot window you can see more in terms of landscape and it's easier to use.
how many windows? As a rule of thumb, we recommend that the visible pane surface should equate to 10% of the room [m2] (and in some countries it’s the law). For instance: If you have a 20 m2 living room, you need at least 2 m2 of visible pane surface. For 2 m2 visible pane surface, you'd have to install (for example) 2 x 114x140 cm roof windows.

5.1 How many roof window should you install?


5.1 How many roof window should you install? As a rule of thumb you have to ensure that there is 50% air-change per hour. Our windows' ventilation capacity depends on the size.




5.2 Case study about ventilation capacity:

5.2  Case study about ventilation capacity: A roof window with a single ventilation valve provides 22 m3/h air. That's enough to refresh a 20 m2 room (4x5 meters, 2,5 m high, 1 m parapet) in one hour.




6.1 How can we position the roof windows?

6.1  How can we position the roof windows? There are of course many ways to position your roof windows, but naturally we recommend installing as many as possible! You can position them next to each other, or on the top of one another or they can just stand alone. But what we do recommend is though that you install the same sizes/types in one room if possible.




6.2 Window Positioning

 6.2 Window Positioning We suggest you split the roof windows as much as possible, to maximise the spread of daylight. The white bubbles represent the light effect of 1, 2, and 4 roof windows in one room




7.1 Take the Roof Construction into Consideration

7.1  Please Take the Roof Construction into Consideration. In general the distance between the rafters should be around 80 cm. When you calculate the size of the window, please add an extra 4-6 cm!




7.2 Working with Rafters

 7.2 Working with Rafters
There are 3 different installation possibilities. If you want to build in a wide roof window, you have to cut the rafters, so please always consult with an engineer to be on the safe side.




8. Planning for Humid Rooms

8. Planning for Humid Rooms In general we recommend that you use wooden roof windows, but in high-humidity rooms it is better to use PVC roof windows, to be condensation resistant.
Questions? Don't hesitate to get in touch with us. We are happy to help.