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10 questions you should ask your rooflight supplier and the answers you should expect.

Choosing the right rooflight supplier can be challenging. You might know whether you need a hinged, sliding or box rooflight, but how do you know what to look for in a rooflight supplier?

Here are 10 questions and answers to help you choose the right rooflight supplier with confidence.

Q1. Do you design and manufacture your own products?
A1. A good supplier will design and manufacture their own products and ideally be specialists in their field. Look for companies with in house design experience and UK manufacturing facilities that will allow you to view the products first hand and ask further questions prior to purchase.

Q2. What type of glass do you use?
A2. Look for a minimum thickness of 6mm and at the very least an insulated double glazed unit. The glass should be heat soak tested toughened safety glass and have a low emissivity (low e) coating which will help reduce solar gain in summer and keep in heat during winter. Hard coat low e coatings are common but the best suppliers use soft coat low e as this increases thermal performance. Heat Soak Tested glass greatly reduces the chance of Nickel Sulphide inclusions that have been known to cause spontaneous fracture of glass. For optimal thermal performance the double glazed unit will also have a warm edge seal.

Q3. What is the U-Value of the rooflight?
A3. This can be a complex subject to understand for the uninitiated. The best rooflight suppliers will be experienced at dealing with u-values and be able to carry out in house 2D thermal modelling to determine thermal performance for any design specification. Building Regulations require a whole rooflight u-value, manufacturers that only quote the glass performance or ‘centre pane’ u-value are giving a false perception of their products performance.

Q4. Can your supplier provide evidence of thermal performance claims?
A4. Providing overall u-values is the very least you should expect, but ideally your supplier will be able to back this up by providing calculations for your specific rooflight, not just generic documentation for a certain specification of glass. Look for thermal reports that clearly break down the various values as these are invaluable when dealing with Building Control or architects.

Q5. What loadings can the glass safely withstand?
A5. This will depend on what application the rooflight is designed to be used for. Loadings for a unit installed on a pitched roof with no access will be different to those units installed in a terrace that can be walked on. Your supplier should fully understand the differences and be able to explain in detail what the glass can withstand and provide specific loadings in accordance with current legislation. For example, UK guidelines currently require a 2.0kN/m2 uniform distributed load (UDL) and 1.5kN concentrated load for walk on specification glass designed for domestic foot traffic. Your rooflight supplier should know this and be able to prove that their glass is strong enough to safely withstand these loads.

Q6. How is the glass fixed into the frame?
A6. There are various ways of doing this which differ depending on the type of product. One of the best ways of securing glass into a frame is to physically bond it using structural sealant. This technology is similar to that used in car windscreens and it means that the glass and frame combine to form a complete structural unit. It is also very efficient at keeping the unit air and water tight so no leaks or drafts.

Q7. What finish is applied to the framework?
A7. Again, depending on what you buy and where you buy it there are various finishes available. One of the most durable and long lasting is a Polyester Powdercoat finish. Look for suppliers that powdercoat their own framework and have suitable quality control measures in place. Qualicoat is an industry recognised organisation that strictly tests its approved applicators facilities and process – only the best in the business will have a Qualicoat Licence so try to find suppliers that have achieved this as it is a guarantee that you will receive the highest quality with paint warranty periods available for up to 30 years by request.

Q8. What safety features are included if my rooflight opens and closes?
A8. Some suppliers offer a range of hinged and sliding rooflights for ventilation and access. Access rooflights are becoming increasingly popular as people start to use space on their roof terrace to add function and value to their living space. As these units are often large and heavy you should ensure that the product you are considering includes appropriate safety features such as soft close mechanisms, current override and proximity detectors.

Q9. Is the supplier a member of the National Association of Rooflight Manufacturers (NARM)?
A9. NARM is an industry body dedicated to the application of best practice in the provision of natural light in built environments. NARM comprises of all the UK’s leading rooflight manufacturers and associated businesses and has been formed to promote co-operation between member companies in order to develop and maintain standards and codes of practice. By selecting a NARM member to supply your rooflights you can be assured that the product will comply with all current standards and regulation.

Q10. Does the supplier have a recognised quality system in place?
A10. Rooflights are the perfect solution when looking to provide natural daylight in a build and as popularity increases so does the number of suppliers in the market. Established suppliers will have robust quality management systems in place to ensure that their process is measured and scrutinised regularly. One of the most recognised is the ISO 9001 standard.

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