rooflighting advantages

Daylight for a better, healthier lifestyle

Plentiful natural daylight is a desirable and beneficial asset for any type of home. Daylight enhances internal environments to make rooms feel more inviting and it brings a number of well-documented health benefits. Research has proven that natural daylight contributes to health and wellbeing, helps people to concentrate and can even improve recovery rates of people with medical conditions or injuries.

Maximise daylight with rooflights

Rooflights and roof windows can let in up to twice as much light as conventional vertical windows and up to 3 times as much light as dormer windows, because the glazing is pointing directly at the light source (the sky & sun) with very little diffused or reflected light.

Rooflights can deliver daylight to areas not served by vertical windows

Adding an extension to your home can result in reducing daylight in the room/s adjacent to the 
extension. A carefully placed rooflight can overcome the problem. Specialist ‘walk-on’ rooflights* can also be installed internally, to deliver daylight to lower floors and cellars.

Rooflights save energy and reduce harmful emissions

Electric lighting accounts for nearly 20% of global energy usage and resulting emissions. By reducing the need for electric lighting, rooflights can make significant savings in these respects. Carefully positioned rooflights can also reduce demands on heating within homes, due to the effects of ‘solar gain’ – although it should be noted that unwanted overheating can result during summer months, if rooflights or shading are poorly specified or positioned inappropriately.

Rooflights can provide ventilation

Rooflights can be supplied with opening sections or incorporate controllable ventilation options which can supplement ventilation to improve indoor air quality.

IMPORTANT CONSIDERATIONS WHEN INSTALLING ROOFLIGHTS

Putting safety first

Properly designed and installed rooflights are intrinsically safe. However, there are a few points to be aware of before starting your project.

Ensure that the rooflights are of an appropriate specification for your home – and compliant with relevant UK standards & legislation. This may sound obvious – however, The Rooflight Association has been made aware of a number of recent instances where inappropriate designs or neglectful installation has led to serious safety concerns. These include:

Shattering of inner panes, which can result in building occupants being exposed to danger from falling glass. To eliminate this risk, ensure your rooflight supplier confirms the use of laminated glass inner panes – or is able to supply a detailed risk assessment, specific to your property. The term ‘toughened’ glass implies safety and whilst it is much stronger than annealed glass, it can in some cases shatter spontaneously, due to manufacturing imperfections resulting in the risk of small pieces of glass falling into the space and onto any occupants below.

Avoidable risk to people accessing roof areas, for maintenance, cleaning or other reasons. Rooflights are classified for levels of non-fragility. It’s important to check with your supplier that your rooflights are appropriately classified, to avoid the risk of falls from height. Most rooflights**, even those with a non-fragile classification, are not designed to be walked on. The non-fragility classifications have been established to ensure safety in the event of someone accidentally falling on the rooflight.

The toughened glass inner pane on this rooflight has shattered. A laminated inner pane should be used.
The toughened glass inner pane on this rooflight has shattered. A laminated inner pane should be used.
The glazing on this rooflight was not properly fixed, resulting in it being blown off in windy weather and ending up in a neighbour’s garden. Luckily, no-one was injured in this instance.
The glazing on this rooflight was not properly fixed, resulting in it being blown off in windy weather and ending up in a neighbour’s garden. Luckily, no-one was injured in this instance.
Correctly designed and installed rooflights like this flat glass unit, should provide years of trouble-free service.
Roof windows for pitched roof applications.

Other pitfalls of poor quality or design

What can appear on first inspection to be a perfectly serviceable rooflight, can be the cause of unexpected and unpleasant surprises, if certain basic rules are not followed by manufacturers and installers – as has proven the case in some recent instances reported to NARM. These can include:

  • Leakage and poor water run-off, leading to damaged internal decorations and/or unsightly build-up of deposits on the rooflight.
  • Compromised security: The Building Regulations state that rooflights deemed as easily accessible need to be proven to resist criminal attack or incorporate features proven to resist crime. To demonstrate this they need to have been tested to one of the security standards listed in Approved Document Q of the building regulations and have achieved a minimum performance standard.
  • Poor thermal performance: The Building Regulations stipulate appropriate levels of thermal performance for rooflights. Thermal efficiency of building products is indicated by a ‘u-value’: the lower the value, the higher the thermal efficiency. For domestic dwellings the required rooflight u-value is 2.0 or less for new build projects and 1.6 or less for refurbishment. These figures apply to the whole assembly, including any upstand, kerb or frame to which the rooflight is fixed. However, to flatter the efficiency of their products, some rooflight suppliers quote ‘centre pane’ u-values which apply only to the glazing, not the complete assembly. It’s therefore extremely important to confirm with your supplier that the quoted u-value is for the whole assembly, not just the glass. This is because the structure around the glazing is often subject to higher thermal losses than the glazing itself. Remember, inadequate thermal efficiency can lead to increased demands on heating and the resulting avoidable increases in harmful emmissions, as well as other problems like condensation or cold spots in your home.
  • Structural integrity: The glass needs to be specified to the correct thickness for the size of the rooflight to resist wind, snow and maintenance loads. The method of securing the rooflight to the upstand also needs to be able to resist these loads. We have been made aware of a a case in which a piece of glass just bonded to a timber upstand where the glass was blown off in high winds and landing in a neighbours garden. Luckily no one was in the garden at the time, had there been at the time there would have been the potential for life changing injuries.
  • Condensation: We have seen a number of rooflights solutions provided that just consist of a stepped edge double glazed unit bonded to the top of an upstand where the inner pane sits inside the supporting structure without any framework. This allows the potential for humid internal air to circulate around the edge of the inner pane to the stepped edge on top of the kerb and form condensation on the underside of the single glass causing the timber to rot and contributing to the breakdown of the bond to the kerb.

In summary: here’s what constitutes a high quality rooflight, suitable for domestic use:

Remember: a great-looking rooflight isn’t necessarily a great rooflight

The good news is that there are many excellent, trustworthy UK suppliers of properly designed rooflights which will offer years of safe and reliable service.

One simple and certain way to ensure you’re dealing with such a company, is to establish whether your supplier is a Rooflight Association member company.

We have stringent membership criteria, a key part of which is that any product supplied by a member company is fully compliant with Building Regulations and meets all required specification and safety standards.

Rooflight Association member companies are listed on this website here

FURTHER READING: BE A ROOFLIGHT EXPERT!

We have published a number of documents giving advice on rooflight design and specification, all of which can be downloaded free of charge from this website. As a homeowner or self-builder, you may find the following of particular interest:

• GETTING ROOFLIGHTS RIGHT – What to ask your builder or architect (introductory leaflet)

• An introduction to natural daylight design through rooflighting (technical specification information)

• An introduction to natural daylight design in domestic properties (technical specification information)

• Roof window installation considerations for pitched roofs (technical specification information)

• Understanding the differences between ‘non-fragile’ rooflights and ‘walk-on’ rooflights for deliberate foot traffic (technical specification information)

*It’s important to note that this type of rooflight is designed to floor loadings, to safely carry the weight of building occupants – and is therefore usually significantly more expensive than conventional rooflights.

** The only exception to this rule is when rooflights are designed to ‘walk on’ specification. These are specialist products for use on roof terraces and other areas where regular foot traffic is to be expected.

The majority of rooflights are not designed to carry the weight of a person and should never be walked upon. However, there is a very specialised class of ‘walk-on’ rooflights which are specifically designed to be installed into floors on roof decks and terraces where pedestrian access is unrestricted. This type of rooflight can bring exciting new design opportunities to maximise useable space.

NOTE: The Rooflight Association website and publications provide extensive free and impartial advice regarding all aspects of rooflights and the benefits of daylight. Rooflight Association officers and members are happy to expand on this advice where appropriate. The Rooflight Association Technical Committee is staffed by volunteers and as such, support and advice is offered freely. The Rooflight Association is not able to carry out visits to sites or specific projects. We do not carry out surveys, produce project specific written reports or conduct forensic investigations in the event of disputes or problems. Such work should be carried out by independent specialist roofing consultants, and we are able to recommend such consultants where required. Rooflight Association members all comply with the Rules of the Association and abide by our Code of Conduct, including ensuring that all Rooflight products are fully compliant with all relevant UK and European Standards and UK Building Legislation, and that all performance claims are verifiable. In the unlikely event that a complaint should be made to The Rooflight Association with evidence that a member’s products or claims do not comply with our Code of Conduct, we will carry out an internal investigation and take appropriate action to resolve the situation.