Useful Information about Architectural Glazing

A Comprehensive Guide to Flat Rooflights for Glass Extensions

Specifying the right flat rooflight for a glass extension

Flat Rooflights for Glass Extensions 


IQ Glass offers many options when specifying flat rooflights for glass extensions. Our guide underpins the key considerations, the benefits, and some examples of flat rooflights installed in some of our projects.  

A flat rooflight is an excellent addition to a glass extension, providing natural light and a feeling of spaciousness to your living space. We have made a comprehensive guide detailing everything you need to know about flat rooflights for glass extensions, from understanding the benefits to choosing the right type and installation. 


Benefits of Flat Rooflights in Glass Extensions 


Rooflights allow natural light to flood into spaces reducing the need for artificial lighting during the day and provide an inviting and modern design that complements the clean lines of a glass extension.  In addition, high performance thermally efficient glazed flat roof lights offer thermal insulation further contributing to energy cost savings.  A key advantage is that flat rooflights provide ventilation for ventilative cooling which improves air quality inside buildings.  For double height spaces with limited access, integrated opening mechanisms within flat rooflights provide the perfect solution, and installed with rain sensors, the rooflight will quietly close when there’s a downpour. 


What Does Minimal-Framed Mean in Flat Rooflights? 


Minimal framed flat rooflights means that the minimalistic design traits that are typical of minimal framed windows and doors applies the same to minimal framed rooflights. The fixings on the frame are concealed maximising uninterrupted views to the sky and light ingress. From the inside space looking out, the rooflight appears totally frameless providing a clean and minimal aesthetic. 


Types of Flat Rooflights in Glass Extensions 


Fixed rooflights such as our frameless, thermally broken Invisio rooflights are static, non-opening rooflights that provide an uninterrupted view of the sky. They can be made to any size or shape, although we would always recommend that they are installed at a 5 degree angle upstand for drainage purposes.  


a frameless rooflight over the kitchen

Bedford Gardens has a static structural rooflight spanning the length of the kitchen area.


Opening Flat Rooflights  


Opening flat rooflights allow light to pass through and offer ventilation often available with fully integrated automation capabilities, such as IQ’s A.R.E.S. (Automated Rising Electric Rooflight) as installed in our Marlborough Avenue Project. The ARES system can be designed to meet almost any size and shape, allowing for enormous flexibility to create truly unique rooflights that break the traditional rectangular mold. This system is designed to open on hinges with concealed actuators maintaining a minimal design. ARES can also achieve circular shapes through engineering multiple actuators to lift an entire vertical sash from the frame.


Glass roof in Marlborough Avenue extension.  

  Marlborough avenue has an opening rooflight installed to an overhang style roof. 


Walk-on Rooflights  


Walk on rooflights are built to withstand foot traffic and are often used for roof terraces or balcony extensions. Low Iron Glass is always recommended due to the thick layers of glass generally needed to create the structural support to the walk on glass rooflight. Another feature of our frameless walk-on glass rooflights is the option to have privacy glass and anti-slip glass.  



Sliding Flat Rooflight Systems for Glass Extensions 


M.A.R.S. Modern Automated Rooflight System is a bespoke flat sliding rooflight is engineered as a system to add ventilation to a space as well as enabling access to a flat roof or terrace. This bespoke and innovative system is available in different sizes, structures and shapes.  

The sliding flat rooflight is perfect for adding ventilation to areas of high humidity such as kitchens and bathrooms, or introducing natural light to spaces where there are no windows. The MARS can be used to provide roof access when creating modern rooftop gardens or terraces, and can be fully integrated to work as part of a smart home system. 


A MARS flat rooflight to Portland Road

MARS flat rooflight system to Portland Road was used at the top of the home as an access rooflight, sliding open easily at the push of a button to grant the home's occupants easy access to their rooftop space. 


High Specification Electric Rooflights with Rain Sensors 


High specification sliding glass rooflights with rain sensors, such as our H.E.R.A. (High spec Electric Rooflight Automation) system uses high specification motors to achieve a smooth and seamless sliding motion and is specified where roof access is required. The H.E.R.A. is engineered with the same minimal design on the inside as the outside, maintaining a minimal appearance like all rooflight systems by IQ Glass.  

The sliding box access rooflight design can be specified in a bi-parting configuration, or in a sliding over fixed configuration and can be finished in any RAL colour.  

In comparison to the MARS system, HERA is not a flat sliding rooflight, but a sliding box rooflight. Both automated sliding roof systems’ motors can be concealed underneath external finishes such as decking or roof shingle and are both equipped with weather sensors as standard.  



Britten Street H.E.R.A. sliding box rooflight to this London property serves as the roof for the double-height extension.  


Lantern Rooflights 


A modern frameless structural glass construction can be engineered into a more traditional lantern shape rooflight. This is achieved by utilising strengthening interlayers or glass beams within the structural glass lantern. These interlayers act as a reinforcement allowing the glass panels to lean against one another without a visible frame and taking the weight load of the structure.  

IQ’s Invisio lantern rooflights make a stylish addition to both modern and heritage buildings creating a bright atrium perfect for kitchens, reading rooms and hallways.


Frameless lantern rooflight

A bespoke frameless glass lantern roof was installed to Solesfield House to maximise natural light aligning with the other traditional features of the original architecture.  


Strip Rooflights to a Glass Extension 


Strip rooflights are narrow strips of frameless structural fixed glass. Strip rooflights are a popular choice of flat rooflight for glass extensions to period properties brightening the deepest part of the building where natural light would not otherwise reach.  Strip rooflights do not require additional support if they are less than 1.3m wide. IQ’s Invisio strip rooflights are precision engineered with a minimal and clean appearance for maximum views and natural light.  


Strip rooflight to glass extension

An oversized strip rooflight forms part of the glass extension to Belgravia House 


Eaves Rooflights to Glass Extensions 


An eaves rooflight (often referred to as a boxed rooflight) are often installed in sloped roofs or areas with limited space to accommodate traditional windows. This rooflight option can deliver the desired balance of light, aesthetics, and functionality to a glass extension. 


Choosing the Right Flat Rooflight for your Glass Extension  

When choosing the right rooflight for your glass extension project, you need to determine the appropriate size based on your room dimensions and the amount of natural light ingress you wish to achieve. Another consideration on sizing the correct rooflight will be the orientation towards the sun. ie. if the space is south facing, solar coatings or a narrow shaped rooflight may help to maintain a more consistent internal temperature.  

A flat opening rooflight installed at a height out of reach should be fully automated with rain sensors for automatic closing when it starts to rain. 

If roof access is required, then a high specification rooflight model should be considered.  

Frame materials should be considered in advance of all residential new build plans and extensions and form part of the SAP calculations assessing the thermal performance of the aluminum, uPVC, or timber frames as well as the glass.  

Safety and security of flat rooflights to glass extensions require toughened or laminated glass for added security.  If the rooflight is installed on an accessible flat roof, more measures should be taken in accordance with Building Regulations Part Q with the inclusion of tested robust locking mechanisms. In Part Q, there is no requirement for PAS 24 certification. 

Ensuring that compliance with Building Regulations is considered from the outset with structural and thermal requirements, it will be easier to choose the right flat rooflight to suit your project.  


Rain sensor to rooflight in glass extension

Flat rooflights offer an abundance of natural light and complement glass extension designs. 


Glass Specification for Extension Rooflights  


Low Maintenance Coatings  

Low maintenance glass is where a low maintenance coating is applied creating an ultra smooth finish that reduces the amount of cleaning and maintenance. Low maintenance coatings are only beneficial for roof glass over 25 degrees fall.


Solar Control Coatings  

Solar control glass contributes to the reduction of cooling costs in highly glazed areas helping to maintain a consistent and comfortable temperature.  

There are a range of solar control coatings available for different levels of light transmission, external tints and solar control. Solar Control coatings must always be used on an insulated glass unit, either double or triple glazed. 


Heated Glass – Snow Load Removal  

Heated glass has been treated to withstand extreme temperatures and stress. It is used in various applications, including windows, doors, and glass roofs. One of the advantages of heated glass is its ability to prevent the buildup of snow and ice, making it a popular choice for roofs maintaining views of the sky. 


Heated glass was installed to the glass igloos at Kakslauttanen Artic Resort for guests to enjoy uninterrupted views of the Northern Lights in the Scandinavian skies.  


Contact our technical team today to discuss structural roof glazing systems for your next project!


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