Discover essential tips for specifying large rooflights, including weight considerations, installation, and safety guidelines.
The Demand for Large Rooflights
As bespoke rooflight manufacturers, we see grand designs with expansive roof glazing to enhance natural daylight. While bespoke rooflights can realize these designs, practical considerations are crucial.
In recent years, larger rooflights have become popular, often exceeding 2500mm in width, height, or both. Stella accommodates these sizes, but weight, transportation, and cost are significant factors.
Larger rooflights require thicker glass, increasing their weight. For instance, our double-glazed units with 4mm thick glass weigh 20kg per square meter, and 6mm glass weighs 30kg per square meter. Triple-glazed units are even heavier. Adding stainless steel frames and hardwood liners further increases weight. Some rooflights can weigh over 200kg.
The Complexity of Specifying Large Rooflights
Scaling up simple plans complicates them. Architects must consider how to lift rooflights from the ground to the roof and the weight implications for the structure. Stella can weld stainless eyelets to the frame for lifting, especially for frames over 100kg, often requiring a crane. Site access and lifting equipment costs should be budgeted.
The weight of an opening rooflight determines whether it is manually operated or needs electric actuation. Manual operation is feasible for rooflights up to 1000mm wide or 1400mm high. Larger sizes typically require electric actuation, affecting cost. Single pieces of glass over 5m² are also significantly more expensive.
Alternatives to Large Single Panes of Glass
Alternatives like glazing bars, linking frames, and multiple casements reduce unit sizes, making rooflights easier to transport, lift, and install, and can also lower costs.
If a large single rooflight is necessary, ensure safe installation. Rooflight manufacturers can advise on materials, glazing thickness, functionality, and installation, but structural engineers must ensure the product is fit and safe for the building.
Involve Experts in Your Rooflight Project
Architects, structural engineers, and rooflight manufacturers should discuss large rooflight installations early to avoid problems. Consider site access, weights, load bearings, and lifting capacity.
Large Rooflights and Safety
Safety is critical for large rooflights in high roof structures. Rooflights should meet BS 5516-2: 2004 standards. Laminated glass is recommended for higher safety. It forms a net when broken, unlike toughened glass which shatters into small pieces.
Rooflights and Thermal Stress
Thermal stress occurs when glass panes heat unevenly, causing cracks. Toughened glass resists thermal stress, while laminated and annealed glass are less tolerant. Consider factors like glass type, building location, rooflight orientation, glazing bars, internal shading, framing material, and nearby radiators to assess thermal risk.
Rooflights and Solar Control Glass
Solar control glass reflects or absorbs energy, getting hotter than clear glass. This can stress the glass, though most installations stay within operating tolerance.
Rooflights and Laminated Glass
Laminated glass is heavier and prone to lensing, distorting images. This affects pitched rooflights with landscape views more than flat ones with sky views.
Conclusion
Specifying large rooflights involves more than adding them to plans. Understanding glazing requirements and involving a structural engineer early can prevent issues later.
