You need to leave the window width plus 20mm to 40mm and the window length plus 20mm to 40mm. It is also important to ensure the top trimmer sits horizontally and the bottom trimmer sits vertically to support the frame.
Maximise Natural Light With Pitched Roof Windows
The Keylite roof windows available in this range provide an effective way to introduce natural daylight and ventilation into single-storey extensions, loft spaces, and renovated pitched roofs. These units fit securely into standard roof pitches ranging from 15° to 90°, making them highly adaptable for a variety of domestic and commercial building designs. Creating a stable opening in the roof structure is a crucial first step, and securing the surrounding framework with heavy duty roofing batten ensures the flashing kits have a solid foundation to sit on.
Installing these windows involves integrating the unit with the existing roofing materials to guarantee weather tightness and strict energy compliance. The built-in thermal collar expands to fill the gap between the window frame and the roof, reducing heat loss significantly. It is essential to pack the surrounding void with appropriate loft insulation to prevent cold bridging and maintain a consistent internal temperature. The frames feature pre-fitted brackets that allow the unit to be secured into the opening quickly, saving time during the fitting process and removing the need to attach separate metal components.
Meeting building regulations is straightforward, as specific sizes within the range provide the necessary unobstructed open area to serve as a fire escape. The external finish of the window sits flush with the roofline, offering excellent weather resistance when paired with the correct flashing kit. If the wider project involves finishing external dormers or vertical surfaces, tying the window installation in with matching slate cladding creates a cohesive, waterproof barrier against the elements. The timber frames are treated to resist moisture, ensuring long-lasting reliability and straightforward compliance with thermal standards.
Keylite Roof Windows FAQ's
The minimum roof pitch required for a standard installation is 15°. If your roof has a lower pitch, a specific flat roof system will be necessary to ensure water drains away effectively.
Positioning a heater directly under the window encourages warm air circulation across the glass. This airflow stops condensation from forming and prevents the timber from remaining damp.
Leaks often happen when the flashing components are not overlapped in the correct sequence, or if the rubber end caps have been accidentally removed. Making sure the frame side flashing sits properly under the C-channels will also prevent water ingress.
A fire escape window must provide an unobstructed open area of at least 0.33m2. This translates to a minimum clear opening of 450mm high and 450mm wide to ensure safe egress in an emergency.