Q.  Why would I choose a Keylite Roof Window instead of a ‘Dormer’ Window?

Compared with a dormer window (regarding the corresponding daylight area), Keylite Roof Windows provide significantly more natural light.  A roof window installed in a roof pitch of 45° provides up to 40% more light than a dormer. The roof window allows unobstructed daylight as opposed to the dormer, where the dormer construction blocks some of the daylight from entering the room.  In addition, it is much easier to install and maintain Keylite Roof Windows compared with a dormer. The dormer construction also has a larger heat loss than a Keylite Roof Window.


Q.  Do Keylite Roof Windows come with a guarantee?

All Keylite Roof Windows are manufactured using the highest quality materials and workmanship, guaranteeing many years of trouble-free enjoyment.  All Keylite Roof Windows have a 10 year guarantee – you can register your roof window by visiting and filling in the online Guarantee Form.


Q.  What size of Roof Window do I need for my room?

We recommend that the daylight area should be at least 10% of the floor area in order to achieve adequate natural daylighting. However, the overall effect can be improved dramatically by increasing the ratio to around 20%.


Q.  My Centre Pivot Roof Window will not remain in the open position. How can this be resolved?

If you have a centre pivot window which is not staying in the open position this may be due to the pitch of your roof.  The springs can be replaced with heavier duty springs that are now as standard within all Keylite Roof Windows.


Q.  Are my Roof Windows secure from the outside?

The opening lights can be fitted with a key-operated locking device, where the windows are required to satisfy the security requirements of NHBC Standards.
It is the responsibility of the building designer to specify where these requirements need to be satisfied (Security against intrusion – BBA Extract).


Q.  Why is there mould in the corners of my window?

Mould will gather in the corners of the window when the timber is continually damp or moist. This is caused by condensation and can be prevented by positioning a heater immediately under the window to provide the ideal pattern of warm air circulation.
This will help prevent condensation gathering on the glass (see window fitting instructions).


Q.  How do I clean a Top Hung Roof Window?

All Keylite Roof Windows rotate 180 degrees, meaning that the outside can be turned to face the inside. Therefore, the windows are able to cleaned safely from inside the property.


Q.  How much space in the roof do I need to leave for a standard Roof Window?

You need to leave the window width plus 20mm-40mm and the window length plus 20mm-40mm. You must also ensure that the top trimmer is fitted in a horizontal position and the bottom trimmer is fitted in a vertical position.


Q.  Why is my roof leaking?

99% of all leaking windows are down to poor installation. The six common installation faults are:
•    C-Channels fitted the wrong way round
•    The hood and top apron are not joined correctly (slate extension piece not fitted)
•    The frame side flashing is not fitted correctly under the C-Channels
•    The rubber end caps have been removed
•    The flashings are not overlapped in the correct order
•    The window has been fitted in a roof with a pitch less than 15°.


Q.  How do electric blinds work?

Keylite can offer either an electrically operated blind, which runs off a wall-mounted transformer switch or a blind that can run off the same remote that is used to operate your window.


Q.  Can I use my own fabric to make a Roof Window blind?

Keylite can supply a roller blind kit that can be used to fit the customers own fabric (we recommend that this is only sold to a blind manufacturer)


Q.  Can any blind be electrically operated?

Keylite can supply an electrically operated pleated and integral blind. We can also provide a battery operated remote control Venetian blind (this includes a different remote than the standard and has a range of approx. 2.5m).


Q.  How do I fit my Roof Window Blinds?

DIY installation is very common with Keylite roof window blinds. Keylite supply fitting instructions with all of our blinds to make this process simple. View our helpful blinds installation video by clicking here.


Q.  What is the minimum roof pitch required for installation of a Keylite Roof Window?

The minimum roof pitch required for a roof Window is 15 ͦ. A flat roof system can be used for a flat roof that has a pitch of less than 15 ͦ.


Q.  Can I get a white finish on any roof window?

The Keylite White Finish painted coating is available for the entire roof window range. The Keylite WF (White Finish) window is ideal for kitchens and bathrooms, or any room prone to smoke, dust or steam. This wipe-clean polyurethane painted coating has fantastic moisture resistant qualities and requires little or no maintenance.


Q.  Do the fire escape Roof Windows have to be a certain height?

A fire escape roof window should have an unobstructed open area that is at least 0.33m2, which is a minimum of 450mm high and 450mm wide.


Q.  How do I weatherproof the flashings on the roof?

Keylite offer a range of dedicated roof flashings for different types of pitched and flat roof coverings, all tested for driving rain resistance.
Flashings are supplied in a range of standard colours or can be colour-matched to specific roof coverings, including composite panel and standing seam systems.
All flashings are manufactured from fire-retardant ABS giving an AA fire rating to BS476, meaning that they can therefore be used on roofs without restriction on number, spacing or position.


Q.  How do I ensure a Roof Window is square in a roof?

The easiest way to check if your window is square is to check the diagonal dimensions. We would advise that you refer to the window fitting instructions that we provide here.


Q.  What flashing do I use with a plain tile roof and a Sun Lite system?

If a Sun Lite is required with a plain tile flashing we can only supply a 250mm diameter rigid system. If a 350mm diameter Sun Lite is required, the Keylite ‘universal top’ Sun Lite can be used for both rigid and flexi.


Q.  Do Sun Lite Tunnels come with a guarantee?

Keylite Sun Lite tubular roof lights have been designed and developed under ISO 9001 quality management systems. The Sun Lite glazing is manufactured from 3mm clear UV-stabilised polycarbonate. This has a 10-year warranty (supported by the polycarbonate manufacturer) against loss of impact strength, excessive yellowing and loss of light transmission.
The production process has also been assessed by the polycarbonate manufacturer and the warranty has been extended to cover any effects of the forming process. The glazing and flashings have been impact-tested to EN 1873 Modular Roof lights and may be deemed to be non-fragile for HSG33 Safety in Roof work. Tubes and elbows have 25-year product warranty, which guarantees that the material will not splinter, yellow, darken, peel off, blister, reflectivity, even after prolonged UV exposure.


Q.  Do you need planning permission for a Sun Lite tunnel?

Not for the smaller sizes as it they are no different to a chimney or flue. If the property is listed or in a conservation area then permission must be obtained. The In-Line or Traditional skylight version is often used in conservation areas as an alternative to the dome.


Q.  Is there a limit to the length of Sun Lite tubing?

Obviously the longer the length of tubing there is, the more light loss there will be down the tube. Using a rigid tube rather than a flexible tube can help to limit the light loss on longer runs.


Q.  What light levels can be achieved with Sun Lite Roof lights?

The light output from the Sun Lite System depends on the external sky conditions, light levels and other influencing factors, such as the type of tube (i.e. flexible or rigid), length and diameter of the tubing and the number of bends in the system.


Q.  What roof opening size is required for the Keylite Flat Roof Window System?

The opening size for the Keylite flat roof upstand is as follows:
•    window width is -20mm
•    window length +175mm


Q.  Is the reflectivity of the Sun Lite tube important?

Yes. The Keylite Sun Tunnel System offers a choice of two reflectance levels; SR85 Specular, which incorporates a pure aluminium layer and has a total reflectance of 95% or the flexible tube, which offers reduced reflectivity.


Q.  What about bends in the Sun Lite system?

For maximum effectiveness, the tubes should be as straight as possible. However, since it is often impractical to site the ceiling diffuser directly below the roof mounted glazing, the rigid tubing system allows an offset by means of two elbows, one at roof level and one at ceiling level.
They are adjustable up to 30° from vertical. There should be no other bends or offsets in tubing as monitoring has shown that these will adversely affect the performance of the system. The flexible tubing offers easier installation, however, the down side of flexible tubing is the reduced reflective performance.


Q.  What is a light and sun deflector?

This is a unique, optional device, which is fitted under the roof glazing.
A light and sun deflector intercepts direct sunlight that would otherwise miss the top of the system at both low and high incident angles, reflecting it down the sun Lite tube.
Monitoring has shown that a south-facing light/sun deflectors can increase the light level at the ceiling diffuser by up to 20% in direct sunlight.


Q.  How do Keylite Sun Lite tubular roof lights contribute to sustainable building design?

Keylite Sun Lite tubular roof lights are an effective and efficient means of maximising natural daylight in dark rooms and areas, virtually eliminating the need for supplementary electric lighting during the day, particularly in corridors. Used to complement artificial lighting, they can considerably reduce the annual energy consumption of any building and, therefore, CO2 emissions.


Q.  How many Roof Windows can be operated from one switch or remote?

We can offer many different systems to suit the buyer, almost anything can be achieved by an electric operation system. For a range of multiple window electrics please contact the Keylite Head Office on +44 (0) 28 8675 8921.


Q.  What distance is required between Roof Windows in a Combi or Bi-Lite?

The distance between the Combi and Bi-Lite is as follows:
• Combi: The Keylite standard Combi flashing requires a distance of 100mm between the window frames. However, we can manufacture the flashing from a minimum of 18mm apart and up to 200mm apart.
• Bi-Lite: The Keylite standard Bi-Lite flashing requires a distance of 100mm between windows.


Q.  What information is required to order a vertical Bi-Lite?

When ordering a Vertical Bi-Lite the following information is required:
•    Roof window size required
•    Depth of vertical window required 600 or 950mm
•    Type of roof window required i.e. CP or TH
•    Is it a single, double, or triple
•    Roof pitch
•    Type of flashing required.


Q.  Can I order the electric kit and fit it to the window myself?

Yes. Electric kits can be retro fitted to a centre pivot window. The kits include all fitting instructions and wiring diagrams required to do so.


Q.  Can a Top Hung Window operate with an electric kit or a smoke ventilation kit?

The Electric and Smoke Ventilation kits work as follows:
• Electric Kit: We can fit an electric kit to a top hung window, but generally this is not advisable.  The advised option is to fit them to a centre pivot roof window were everything would be out of sight.
• Smoke Vent Kit (SVK): A Top Hung window does not meet regulations with regards to providing the required ventilation levels for smoke ventilation.


Q.  Do electrically operated integral blinds operate with the Roof Window remote control?

Yes, we can programme our remote control to operate the integral blind or blinds system.


Q.  Is factory fitting an electric operation kit more expensive?

Factory fitting an electric operation kit for our roof windows will not cost any extra.
If a window is ordered along with an electric kit we will fit it free of charge.