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5 little ways to stop big rooflights causing you problems

Beautiful modern building designs often feature expansive glazing, but it is important to get expert help to understand the on-site implications of what you specify

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Large bespoke Stella rooflight. What are the weight implications for the structure? How will the rooflight be lifted to roof level?
Large bespoke Stella rooflight. What are the weight implications for the structure? How will the rooflight be lifted to roof level?

Architects are always on the lookout for innovative daylighting solutions and specifying bespoke rooflights can help achieve successful building designs.

However, larger rooflights - those exceeding 2500mm in width or height - can introduce some practical challenges.

Weight Double glazed units with 4mm thick glass weigh 20kg per square metre, while those with 6mm thick glass weigh 30kg per square metre. Triple glazed units are even heavier. Adding stainless steel frames and hardwood liners can make rooflights as heavy as 200kg.

Installation Scaling up rooflight sizes also complicates installation. It is crucial to consider how the rooflight will be lifted to roof level and the weight implications for the structure. For frames over 100kg, Stella can weld on stainless steel eyelets to aid lifting, and a crane may be necessary. Ensuring site access for lifting equipment and budgeting for these additional costs is essential.

Operation The weight of an opening rooflight determines whether it is manually operated or requires electric actuation. Manual operation is suitable for rooflights up to 1000mm wide or 1400mm high; larger sizes generally need electric actuation, increasing costs. While there is no maximum size for manufacturing, glass over 5m² becomes significantly more expensive.

  • Additional bespoke features such as hardwood liners make rooflights heavier.
    Additional bespoke features such as hardwood liners make rooflights heavier.
  • For frames over 100kg, Stella can weld on stainless steel eyelets to aid lifting.
    For frames over 100kg, Stella can weld on stainless steel eyelets to aid lifting.
  • Large Stella rooflights - this one is installed on a zinc roof - add value and become focal points.
    Large Stella rooflights - this one is installed on a zinc roof - add value and become focal points.
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Design alternatives To mitigate costs and installation difficulties, consider alternatives such as introducing glazing bars, linking frames or using multiple casements. These options make rooflights easier to transport, lift and install and can also reduce costs.

Safety and standards Safety is paramount when installing large rooflights. Rooflights must meet BS 5516-2: 2004 standards, which mandate laminated inner panes for rooflights more than five metres above floor level or over water. Laminated glass is safer than toughened glass as it forms a net when broken, unlike toughened glass, which shatters into cubes. However, laminated glass poses risks of thermal fracture and heat stress, which can be mitigated by polishing edges and using solar control glass such as SGG Cool-Lite.

Specifying large rooflights involves more than just adding them to plans. Early involvement of a qualified structural engineer, along with recommendations from the rooflight manufacturer, can prevent issues and ensure a successful installation.

For more information and technical support, visit stellarooflight.co.uk

Contact:
01794 745445
info@stellarooflight.co.uk


 

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