Roof lanterns are a popular choice for flat roof extensions, renovations and new-build projects, providing natural light without sacrificing valuable wall space. However, selecting the right system involves more than choosing a size and frame colour.
For installers, builders and contractors, important considerations include the roof opening, frame material, glazing specification, thermal performance and installation requirements.
This guide covers the key factors to consider when specifying a roof lantern and helping customers choose the most suitable option for their project.
1. Aluminium or uPVC Roof Lanterns?
Both aluminium and uPVC roof lanterns offer practical solutions for flat roof installations, but there are differences worth considering.
Aluminium roof lanterns
Aluminium offers excellent strength and rigidity, allowing for slim profiles and larger glazed areas. Modern thermally broken systems combine contemporary styling with good thermal performance.
Aluminium is particularly suitable for projects where minimal sightlines, larger spans or a modern architectural appearance are priorities.
uPVC roof lanterns
uPVC roof lanterns provide a practical, low-maintenance alternative, often at a more economical price point.
They can be particularly suitable for domestic extensions and renovation projects, especially where the customer wants to coordinate with existing uPVC windows and doors.
Both materials offer good durability and weather resistance when correctly specified and installed.
2. Getting the Size and Configuration Right
The roof opening and structural design will influence the size and configuration of the lantern.
Before ordering, consider:
- Opening dimensions: Confirm the finished structural opening and the manufacturer’s measurement requirements.
- Upstand design: Check the required height, width and construction of the supporting kerb.
- Glazing configuration: Larger lanterns may require additional glazing bars depending on the system and dimensions.
- Roof structure: Ensure the opening, supporting structure and surrounding roof are designed for the proposed installation.
- Access: Allow for safe installation, glazing and future maintenance.
A larger lantern doesn’t always provide the best result. Positioning and proportion are equally important, particularly on smaller extensions.
It’s also essential to distinguish between the structural opening, finished upstand dimensions and overall lantern size. Always follow the manufacturer’s specific measuring guidance.
3. Thermal Performance and Glazing
Thermal performance should be considered early in the specification process, particularly for heated spaces such as kitchens, dining rooms and open-plan extensions.
Modern roof lanterns use thermally efficient glazing and frame designs to reduce heat loss.
Key considerations include:
U-values
U-values measure the rate of heat transfer through a building element. The lower the U-value, the better its insulating performance.
Check whether quoted figures refer to the glazing unit alone or the complete roof lantern, including the frame. These figures should not be treated as interchangeable.
Solar control glazing
Large areas of overhead glazing can increase solar gain, particularly on south-facing roofs.
Solar control glazing can help reduce excessive heat build-up during warmer weather while still allowing natural light into the room.
Light transmission
The glazing specification also affects how much visible light enters the property. Solar control, tint and light transmission should be considered together rather than independently.
The most appropriate specification will depend on the building design, orientation and applicable Building Regulations.
4. Roof Pitch, Drainage and Weatherproofing
Roof lanterns are generally installed on flat or low-pitched roofs, but the glazed structure itself incorporates a pitch to encourage water run-off.
The pitch varies between systems and should be checked against the manufacturer’s specifications.
Correct installation is essential for long-term weather resistance. Pay particular attention to:
- Upstand construction and weatherproofing.
- Integration with the existing roof covering.
- Flashing and sealing details.
- Drainage around the lantern.
- Manufacturer-specified fixings and installation procedures.
Poorly constructed upstands or incorrect waterproofing details can cause problems regardless of the quality of the roof lantern itself.
5. Ventilation and Condensation
Roof lanterns can help create bright, comfortable interiors, but ventilation and condensation control should form part of the wider room design.
Condensation is influenced by internal humidity, surface temperatures, insulation and ventilation.
Thermally broken frames and energy-efficient glazing help reduce the risk of cold internal surfaces, but they do not eliminate the need for appropriate ventilation.
For kitchens and other moisture-producing spaces, consider how the lantern works alongside existing windows, extract ventilation and other airflow provisions.
Some roof lantern systems also offer integrated ventilation options, which may be useful where additional airflow is required.
6. Choosing the Right Roof Lantern System
Different projects have different priorities, whether that’s slim sightlines, thermal efficiency, appearance, budget or ease of installation.
DRS supplies a range of roof lanterns and rooflights for trade customers, including:
Sheerline S1 Roof Lantern
An aluminium system featuring slim profiles, thermally efficient construction and a choice of configurations. Particularly suitable for projects where contemporary styling and thermal performance are important.
Eurocell Skypod Roof Lantern
A versatile uPVC roof lantern system offering a choice of configurations, finishes and glazing options. A practical solution for domestic extensions and renovation projects.
View our Skypod roof lantern range for technical specifications and available sizes.
Luma Rooflights
A contemporary rooflight option for projects where a streamlined appearance is preferred.
The right choice will depend on the available roof space, structural requirements, design preferences and project budget.
7. Final Checks Before Ordering
Before confirming a roof lantern order, it’s worth running through a few essential checks.
- Confirm the finished opening and upstand measurements.
- Check the selected system’s size and configuration limits.
- Confirm the glazing specification and required thermal performance.
- Check frame colours and finishes.
- Review installation and waterproofing requirements.
- Confirm access, delivery arrangements and installation schedule.
Taking time to check these details can help avoid ordering errors, delays and unnecessary adjustments on site.
Roof Lanterns for Trade Installers from DRS
At Direct Roofing Systems, we supply roof lanterns and rooflights to installers, builders and contractors throughout the UK.
With a choice of systems, competitive trade pricing, technical support and nationwide delivery using our own fleet, we aim to make sourcing the right products straightforward.
Explore our roof lantern and rooflight range or contact our team to discuss your project requirements and request a quotation.
