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, NARM 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.
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. NARM has received a case of 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: NARM has seen a number of rooflights solutions provided that jus 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:
- Design that integrates the glazing within the frame or upstand to ensure secure fixing
- Glazing thickness that is appropriate to the size of the rooflight
- ‘Whole product’ u-value of 2.0 or less for new build and 1.6 or less for refurbishment
- Laminated glass inner pane
- Appropriate non-fragility classification
- Appropriate security classification
- Correct installation with sufficient incline to allow water run-off
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 NARM member company. NARM has 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. NARM member companies are listed on this website:
FURTHER READING: BE A ROOFLIGHT EXPERT!
NARM has 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)
• Roof window installation considerations for pitched roofs (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.
NOTE: The NARM website and publications provide extensive free and impartial advice regarding all aspects of rooflights and the benefits of daylight. NARM officers and members are happy to expand on this advice where appropriate. The NARM Technical Committee is staffed by volunteers and as such, support and advice is offered freely. NARM is not able to carry out visits to sites or specific projects. NARM does 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 NARM is able to recommend such consultants where required. NARM members all comply with the Rules of the Association and abide by the NARM 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 NARM with evidence that a member’s products or claims do not comply with the NARM Code of Conduct, NARM will carry out an internal investigation and take appropriate action to resolve the situation.
