In the latest of our FAQ series, Graham Copson, Technical Manager of Klober, takes us through some of the more common queries received by the company’s technical department. For more roofing FAQs from Klober click here.
How many flat roof vents do I need for my roof?
We would normal recommend installation to BS 5250 on flat roofing. On a ventilated, flat roof, you need to provide a continuous 25mm ventilation across two sides to create a cross flow from one side to the other.
If you look a 125mm flat roof breather vent which provides around 12,500mm2 of ventilation, you would need to be install one every 0.5m across two (to meet BS 5250). This is providing that there are no obstacles such as party walls, skylights etc. that may affect cross flow. If so, additional vents would need to be installed either side of the obstacle.
What would you recommend repairing cuts and scuffs on a membrane?
Scuffs and cuts are common and almost inevitable when installing roofing membrane, and they should always be sealed off using a proprietary tape – such as our Permo TR Tape. It’s also good for creating airtight seals between laps in underlays or sealing around pipe sealing collars. To find out more, visit http://klober.co.uk/shop/product/permo-tr-plus.
What is the difference between bitumen, high impact PVC and ‘snap in’ flat roof vents?
The only difference between the three styles of flat roof vents is their connection method: the bitumen has a bitumen flange perfect for installing alongside bitumen materials; the high impact PVC has a PVC base suitable for fibre glass installations and the universal ‘snap in’ is the solution for single ply roofing.
To submit your question for next week’s FAQs, simply email pb@hamerville.co.uk
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