A well-chosen rooflight can transform a flat-roof extension, kitchen or orangery by bringing daylight into the centre of the room. But “rooflight” can mean anything from a slim fixed glass panel to a large aluminium roof lantern, and those products differ in appearance, price, glazing, ventilation and the way they must be measured. The right option depends on your roof construction, room size, budget, orientation and whether you want a discreet source of daylight or a statement feature. This guide explains the main types, glazing options, sizing, kerb requirements, colours, ventilation, installation considerations and current UK guide prices. It also highlights the checks to complete before ordering a made-to-measure unit. Quick answer: choose a roof lantern when you want a raised architectural feature that brings light into the room from several angles. Choose a flat rooflight when you prefer a low-profile, contemporary finish or have a smaller roof opening. Before ordering: identify the exact product first, then check whether it is sized to the structural opening, internal kerb, external kerb or overall frame. Made-to-measure units often cannot be changed or returned once production begins. A raised roof lantern creates an architectural feature, while a flat rooflight gives the roof a lower-profile finish. Contents Roof lantern or flat rooflight? Types of rooflight Quick Apex product comparison Fixed or opening rooflight? Glass and thermal performance How much glass does a room need? Structure, kerb and measurement Fall, waterproofing and safe installation Overheating and condensation Colours and appearance UK guide prices Planning permission and Building Regulations Buying checklist Frequently asked questions Roof Lantern or Flat Rooflight? A roof lantern is a raised structure made from several pitched glazed panels, while a flat rooflight is a low-profile glazed unit installed close to the roof surface. Both bring natural light into a room, but they create very different results. Feature Roof lantern Flat rooflight or skylight Profile Raised, pitched glazing that creates a feature Low-profile and close to the roof surface Best for Extensions, orangeries and larger rooms Contemporary interiors and smaller openings Daylight Enters from several directions Enters mainly from directly overhead Appearance Traditional or contemporary statement feature Minimalist and understated Frame options Aluminium or uPVC, depending on the system Usually a slim aluminium or proprietary frame Ventilation Available on selected systems Fixed or opening, depending on the model Maintenance More glass and framework to clean Simpler external surface, but safe access is still required Typical price Higher Lower entry price A lantern can become the focal point of an extension, particularly above a kitchen island or dining table. A flat rooflight gives a cleaner finish and can appear almost frameless when viewed from inside. The terms rooflight, skylight and roof window are sometimes used interchangeably. Always rely on the chosen product’s technical drawings and installation instructions rather than the product name alone. Brightside Slimline: a low-profile fixed flat glass rooflight. Korniche Contemporary: a raised aluminium lantern designed as a statement feature. Types of Rooflight Contemporary aluminium roof lanterns The Korniche Contemporary Aluminium Roof Lantern combines slim aluminium profiles with large areas of glass. It suits modern extensions where you want a statement feature without heavy-looking glazing bars. It is available in bespoke sizes and is listed with clear solar-control and self-cleaning glass. Check the available colours, finished kerb dimensions and current lead time for your chosen configuration. Pyramid roof lanterns The Korniche Pyramid Roof Lantern uses a four-sided pyramid design for square roof openings. Its symmetrical shape works particularly well when positioned centrally above a dining area, kitchen island or seating space. It combines a slim aluminium structure with self-cleaning Low-E glass and is manufactured to suit the specified kerb size. Aluminium lanterns with laminated inner glass The Brett Martin Aluminium Roof Lantern is a thermally broken, double-glazed aluminium system with a laminated inner glass pane. Clear self-cleaning and blue solar-control self-cleaning glass options are listed, together with a 10-year manufacturer’s warranty. The laminated inner pane is an important consideration for buyers who want additional protection beneath overhead glazing. Custom-size uPVC roof lanterns The Wendland Roof Lantern is a made-to-measure uPVC system with self-cleaning glass and solar-control options. It is useful where a standard size does not suit the existing kerb or where a uPVC frame coordinates better with the property’s windows and doors. Optional manual or electric opening vents are available on selected configurations, making Wendland a strong starting point for kitchens and other rooms that need additional ventilation. Slimline fixed flat glass rooflights The Brightside Slimline Flat Glass Skylight is the lowest-priced low-profile option in the current Apex range. Its slim frame, double glazing and fixed design suit projects where the priority is daylight rather than ventilation. Check the complete glazing and installation specification for the intended application before ordering, particularly where the unit will be positioned above an occupied area. uPVC SkyPod roof lanterns The SkyPod Skylight is a pitched uPVC glazed system for flat-roof extensions, kitchen-diners, garage conversions and orangeries. It has a fixed 20-degree pitch, a choice of colours and a listed 10-year guarantee. When comparing thermal performance, check whether the quoted U-value applies to the glass or the complete unit, as those figures are not directly interchangeable. Quick Apex Product Comparison Product Best for Key buying point Brightside Slimline Budget-friendly fixed flat rooflight Low-profile fixed unit; check glazing specification, delivery charge and returns eligibility Korniche Contemporary Modern aluminium statement lantern Bespoke sizes with solar-control and self-cleaning glass options Korniche Pyramid Square openings and symmetrical designs Made-to-measure aluminium pyramid; order to the specified kerb dimensions Brett Martin Buyers prioritising a laminated inner pane Thermally broken aluminium frame and two self-cleaning glass options Wendland Non-standard openings or optional ventilation Custom-size uPVC system with manual or electric vent options SkyPod uPVC windows and larger pitched designs Fixed 20-degree pitch; measure the external kerb carefully Browse all Apex Roof Lanterns and Flat Rooflights or call 0800 612 7903 if you need help narrowing down the options. Fixed or Opening Rooflight? A fixed rooflight is sealed and designed primarily to bring daylight into the room. It normally costs less than an opening model and contains fewer moving components. Fixed rooflights work well in: Living rooms and dining rooms Hallways and circulation spaces Extensions with opening windows or external doors Rooms that already have suitable mechanical or natural ventilation An opening rooflight or ventilated roof lantern can help release warm air, moisture and cooking vapour. It may be worthwhile in: Kitchens and kitchen-diners Bathrooms and utility rooms Large south- or west-facing extensions Rooms that become hot in summer Spaces with limited opening windows An opening vent does not replace solar-control glazing, shading or a properly designed ventilation strategy. Its effectiveness also depends on lower-level air inlets and the layout of the room. Plan ventilation before ordering. Retrofitting an opening mechanism to a fixed unit is generally not practical. Glass and Thermal Performance Overhead glazing has to manage safety, heat loss, solar gain, glare and weather exposure. The glass specification therefore matters just as much as the frame. Illustrative comparison of clear laminated glazing, solar-control glazing and a self-cleaning external surface. Confirm the certified glass build-up for the exact product before ordering. Laminated inner glass Laminated glass contains an interlayer that helps hold broken glass together instead of allowing loose pieces to fall into the room. It is commonly preferred for overhead glazing, but the required specification depends on the product, pane size, height, location and project-specific risk. Choose a certified rooflight system and make sure its glazing is suitable for the intended installation. Where the position or application is unusual, seek confirmation from the manufacturer, installer or Building Control body. The Brett Martin lantern is listed with a laminated inner pane. Double or triple glazing Double glazing is suitable for many domestic projects when the complete unit and surrounding roof meet the applicable thermal requirements. Triple glazing can reduce heat loss further, but it normally costs more, weighs more and may require additional structural support. A well-specified double-glazed unit may therefore be the better overall choice for many extensions. Solar-control glass Solar-control glass reduces the amount of solar heat entering the room. It is particularly useful for: South- and west-facing extensions Large areas of overhead glazing Kitchen-diners that already generate heat Rooms with limited ventilation Spaces affected by strong glare Solar control involves a balance between heat reduction, visible light transmission and glass appearance. For a large opening, ask for the glass g-value and visible light transmission where available rather than judging the option by tint alone. Self-cleaning glass A self-cleaning coating uses daylight and rainwater to help loosen and remove external dirt. It can reduce maintenance, but it does not make the glass maintenance-free. Frames, seals and areas where water does not drain freely may still need cleaning. Plan safe access for future maintenance. A standard rooflight should never be used as a foothold. Understanding U-values A U-value measures how readily heat passes through a building element. The lower the U-value, the better the thermal performance. Before comparing two products, establish whether the published figure refers to: The centre pane of the glass The complete glazing unit The complete rooflight, including the frame A vertical or inclined testing position A glass-only value should not be compared directly with another product’s whole-unit value. Heat can also be lost through the frame, edge spacer, kerb and installation detail. In England, the relevant energy-efficiency guidance is contained in Approved Document L. Wales, Scotland and Northern Ireland have their own regulations and technical guidance. How Much Glass Does a Room Need? As a broad starting point, the glazed area may represent approximately 5–15% of the room’s floor area, but this is not a fixed design rule or a substitute for a daylight and overheating assessment. The most suitable size also depends on: The depth and shape of the room Ceiling height Existing windows and doors The direction the room faces Nearby walls, trees and buildings Glass light-transmission levels Summer overheating and glare risk Structural and energy-efficiency requirements The position of kitchen units, furniture and shading A larger rooflight admits more daylight, but bigger is not always better. Too much overhead glazing can increase solar gain, glare, winter heat loss, structural work and total project cost. Structure, Kerb and Measurement Check the roof structure first Before creating or enlarging an opening, establish the direction, spacing and load-bearing role of the roof structure. Cutting joists, rafters or beams may require trimming, additional framing or structural calculations. Large lanterns impose different loads from small fixed rooflights. A competent builder or structural engineer should advise where the opening is large, the existing structure is unusual or the selected unit is particularly heavy. Do not form the opening from the nominal product dimensions alone. How to measure correctly Rooflights are not all measured in the same way. Depending on the manufacturer, the stated size may refer to: The structural opening The internal kerb or upstand The external kerb The overall external frame The visible glass area Brett Martin, Wendland and SkyPod products are listed using external kerb dimensions. Other systems may use a different reference, so start with the technical drawing for the exact product. Before ordering: Choose the product and configuration. Read the manufacturer’s measuring and installation guide. Identify the exact measurement required for ordering. Include the finished waterproofing build-up where instructed. Measure the length and width in more than one position. Compare the diagonals to check that the kerb is square. Check the required kerb width, height and minimum fall. Ask your builder or installer to verify the final measurements. Measure the finished kerb using the reference specified by the manufacturer, then check the length, width and diagonals before ordering. A unit described as 1000 × 2000 mm external kerb size will not necessarily fit a structural opening of 1000 × 2000 mm. The relationship depends on the selected system. Builder’s kerb or upstand A flat-roof rooflight normally sits on a raised builder’s kerb, also called an upstand. The kerb: Raises the glazing above standing water Provides a secure fixing surface Creates space for insulation Allows the roof covering to be dressed and sealed correctly Keeps the rooflight away from drainage paths A finished upstand height of around 150 mm is a common flat-roof detailing benchmark, but the exact height, width, construction and insulation must follow the selected rooflight and roofing-system instructions. The kerb should be insulated and integrated into the waterproofing to limit heat loss, water ingress and condensation. On a GRP roof, the laminate and corner details must be formed correctly around the upstand. On an EPDM roof, the membrane and corners must be bonded and sealed with compatible products. If the waterproof covering is being installed at the same time, explore the Apex 600g GRP Roofing Kits or use the ClassicBond EPDM Kit Builder. Brightside rooflight cross-section. Always use the detail supplied for the selected size and specification. Brightside measuring guide showing why the order size must follow the manufacturer’s stated reference. Fall, Waterproofing and Safe Installation A “flat” rooflight should not automatically be installed completely level. Many flat glass units require a minimum fall to encourage rainwater to drain from the glass and help a self-cleaning coating work correctly. Before forming the kerb, establish: The minimum pitch or fall The direction of drainage Finished kerb dimensions Fixing method Compatible flashing or perimeter details Waterproofing and membrane requirements Insulation continuity The rooflight, kerb and roof covering should be treated as one compatible system. General-purpose sealant should not be relied on as the primary waterproofing method unless the manufacturer’s instructions specifically permit it. Do not leave an opened roof exposed to the weather. Larger units may also require specialist lifting equipment and enough safe access for the delivery team and installer. Can you walk on a flat rooflight? Never stand or walk on a rooflight unless it is specifically designed, tested and sold as a walk-on unit. A standard flat glass rooflight may look strong but should not be treated as a walking surface. Roof terraces, balconies and maintenance routes require a product certified for that purpose, together with suitable structural support and guarding. Overheating and Condensation Reducing summer overheating A large roof lantern can increase summer heat gain, especially in south- and west-facing rooms. Consider: Solar-control glazing The total area of overhead glass Opening vents External or internal shading Room orientation Existing windows and doors Mechanical ventilation Glare and visible light transmission Opening vents can release hot air, but they do not stop solar radiation from entering the room. For large glazed areas, decide on solar-control glass and shading before ordering because they can be difficult or impossible to add later. Reducing condensation Condensation occurs when warm, moisture-rich indoor air reaches a colder surface. Kitchens, bathrooms and newly plastered extensions can create particularly high humidity. Reduce the risk by: Choosing an efficient glazed unit Using a thermally broken frame where available Insulating the kerb correctly Maintaining continuity in the surrounding roof insulation Providing suitable background and purge ventilation Using extraction or opening vents where appropriate Following the manufacturer’s sealing and installation details A good glass U-value cannot compensate for a poorly insulated or incorrectly detailed upstand. Colours and Appearance Most aluminium roof lanterns use a durable powder-coated finish. Popular choices include: Anthracite Grey, RAL 7016 — a popular contemporary finish that coordinates with many modern windows, doors and roofline products Black — a high-contrast option for modern interiors and exteriors White — a traditional choice that works well with light interiors and white window frames Illustrative aluminium frame finishes: Anthracite Grey RAL 7016, black and white. Check the available internal and external colours for the selected system. Wendland and SkyPod uPVC systems are also available in selected colours and finishes. Check both the internal and external frame colour. Some products use different finishes inside and outside; the Brett Martin lantern, for example, is listed with an anthracite grey exterior and white interior. UK Guide Prices Prices depend on size, frame material, glazing, colour, ventilation and whether the unit is made to measure. These are product-only starting prices, not supply-and-fit costs. Type Product Guide price from Fixed flat glass rooflight Brightside Slimline £238.14 Custom-size uPVC lantern Wendland £694.08 Contemporary aluminium lantern Korniche Contemporary £897.60 Pyramid aluminium lantern Korniche Pyramid £985.03 Aluminium lantern with laminated inner pane Brett Martin £1,169.48 uPVC pitched lantern SkyPod £1,410.40 Guide prices checked against the listed product information on 18 September 2026. Prices, specifications and delivery charges can change. Select the exact size and options on the product page before ordering. The product price will not normally include: Creating or altering the structural opening Structural calculations or additional framing Constructing and insulating the kerb GRP or EPDM waterproofing Flashing, trims or fixing components not supplied with the unit Installation labour Internal plastering and decoration Electrical work for powered vents Scaffolding, lifting equipment or difficult-access charges Building Control or professional fees where applicable Waste removal and making good Delivery, returns and made-to-measure orders Delivery charges and lead times vary by product, size, postcode and availability. At the time of the price check, the product information indicated: Brightside Slimline: delivery charged separately by postcode, with a typical listed lead time of 5–7 days Korniche Contemporary: mainland UK delivery available under the current product terms Korniche Pyramid: an indicated lead time of approximately 10 working days Brett Martin: approximately 3–5 working days, depending on specification and availability Wendland: mainland delivery available, with surcharges for selected postcode areas and offshore locations SkyPod: delivery and availability dependent on the selected size Many lanterns and rooflights are manufactured for a specific order. Check the size, colour, glazing, vent options, delivery address, site access and cancellation terms before payment. Which Apex Rooflight Is Right for Your Project? Wendland: custom-size uPVC roof lantern with selected ventilation options. Korniche Pyramid: a symmetrical design for square openings. SkyPod: a pitched uPVC option designed to coordinate with uPVC windows and doors. Your project Best starting point Budget-friendly fixed rooflight for a smaller opening Brightside Slimline Contemporary aluminium statement feature Korniche Contemporary Square opening requiring a symmetrical design Korniche Pyramid Laminated inner pane is a priority Brett Martin Non-standard opening or optional ventilation Wendland uPVC lantern to coordinate with existing windows and doors SkyPod If two products appear suitable, compare the frame material, complete glazing specification, whole-unit thermal performance, solar-control data, warranty, delivery cost, installation requirements and returns conditions — not only the starting price. Planning Permission and Building Regulations Planning permission and Building Regulations are separate matters. A project can fall within permitted development rights and still require Building Regulations approval or notification. Planning permission In England, some roof alterations can fall within permitted development rights when all relevant conditions are met. Planning Portal guidance includes limits on how far certain alterations may project beyond the existing roof plane, but that should not be treated as automatic approval for every flat rooflight or raised lantern. A roof lantern installed as part of a new extension may be assessed with the extension rather than as an isolated roof alteration. Additional controls may apply when: The property is listed It is in a conservation area An Article 4 Direction applies Permitted development rights have been removed The building is a flat or maisonette The proposal affects a sensitive elevation The lantern changes an already approved extension design Read the current Planning Portal roof guidance and check the position for the property before work begins. Planning systems differ across England, Wales, Scotland and Northern Ireland. Building Regulations Depending on the project, the rooflight, surrounding roof and installation may need to satisfy requirements covering: Structural stability Energy efficiency Safety glazing and impact protection Fire safety Ventilation Moisture and weather resistance Drainage and insulation continuity For a large opening, altered roof structure, extension, fire-separation issue or unusual installation, consult a competent builder, structural engineer or Building Control body. Buying Checklist Before ordering: Choose between a raised lantern, flat rooflight or opening unit. Check the roof structure and whether additional framing or calculations are required. Decide whether the room needs ventilation, shading or solar-control glass. Compare equivalent whole-unit thermal and glazing figures. Use the exact manufacturer’s measuring method. Distinguish between structural opening, internal kerb, external kerb and overall frame size. Check the kerb height, width, insulation and required fall. Review the waterproofing, fixing and membrane details. Check the internal and external frame colours. Review planning and Building Regulations requirements. Check delivery charges, lead time, site access and lifting requirements. Read the warranty, cancellation and made-to-measure returns conditions. Ask your builder or installer to verify the final dimensions before payment. Frequently Asked Questions What is the difference between a roof lantern and a skylight? A roof lantern is a raised structure made from several pitched glazed panels. A skylight or flat rooflight is a lower-profile glazed unit installed close to the roof surface. Lanterns create more architectural impact; flat rooflights provide a cleaner, more understated finish. Can you put a roof lantern on a flat roof? Yes. Roof lanterns are designed to sit on a raised, waterproofed and insulated kerb formed within a flat roof. The roof structure and kerb must suit the size and weight of the selected lantern. How do I measure for a roof lantern? Follow the instructions for the exact product. Some systems are ordered using the external kerb size, while others use a different reference. Measure in several positions, compare the diagonals and have the finished dimensions checked before ordering. What happens if I order the wrong size? Made-to-measure units often cannot be changed, cancelled or returned once production starts. That is why the measuring method and finished kerb dimensions must be checked before payment. What size roof lantern do I need? It must first suit the roof structure and finished kerb. As a broad daylighting guide, the glazed area may represent around 5–15% of the room’s floor area, but orientation, existing windows, room depth and overheating risk also matter. Is double or triple glazing better? Triple glazing can improve thermal performance but increases cost and weight. A high-quality double-glazed system may be suitable for many domestic projects. Compare figures for equivalent parts of the product, ideally the complete unit. Is laminated glass necessary? Laminated inner glass is commonly preferred for overhead glazing and is required in certain applications. The correct specification depends on the product, height, pane size, location and project risk, so use a certified system suitable for its intended position. Should I choose clear or solar-control glass? Solar-control glass is useful for large, south- or west-facing rooflights and rooms at risk of overheating or glare. Clear glass may suit smaller openings, north-facing rooms or spaces where maximum visible light is the priority. Do I need an opening rooflight? An opening model is useful in kitchens, bathrooms and rooms affected by excess heat or humidity. A fixed unit may be sufficient where the room already has suitable windows, doors or mechanical extraction. Can I walk on a flat glass rooflight? Not unless it is specifically tested, certified and sold as a walk-on rooflight. A standard unit must never be treated as a walking surface. What colour roof lantern is most popular? Anthracite Grey, RAL 7016, is a popular contemporary choice and coordinates with many modern windows, doors, cladding and roofline products. White and black are also available on selected systems. Does Apex deliver rooflights throughout the UK? Delivery availability, charges and lead times vary by product, postcode, size and destination. Some units include mainland delivery under their current terms, while others have separate regional charges. Check the delivery details shown for the selected product. Choose the Right Rooflight First Time The best rooflight is not automatically the largest or most expensive. It is the product that fits the completed kerb, provides the right balance of daylight and solar control, meets the project’s thermal and safety requirements and suits the appearance of the building. Browse all Apex Roof Lanterns and Flat Rooflights or call the Apex team on 0800 612 7903 for help choosing a product for a non-standard opening. Building or re-covering the flat roof at the same time? Explore the Apex 600g GRP Roofing Kits or configure a ClassicBond EPDM roofing kit for your project.
