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Installing flat roof skylights: minimum pitch guidance

Installing flat roof skylights: minimum pitch guidance

Sunsquare have been innovating skylight design for well over a decade. In this article they answer questions about the minimum pitch for flat roof skylight installations.

After investing in the abundance of daylight a skylight provides, it’s important that users are assured of the long-term performance and stability of the product through a thoroughly professional installation service.

Why is recommended pitch so important?

While a definitive recommended pitch might be difficult to establish, due to the breadth of skylight products on offer, the pitch of your rooflight is vital for:
• Compliance with Building Regulations
• Prevention of puddles forming, which can stain or mark the glazing
• Ensuring maximum ‘flex’, or weight-bearing capability, is accounted for

Recommended pitch for fixed skylight installations

A conventional fixed skylight, such as our own SkyView, should ultimately be fitted at a minimum pitch of three degrees in flat roofs.

Three degrees represents the correct angle to ensure rainwater runs easily from a skylight’s surface into drains and gutters. This prevents unsightly marks caused by ‘ponding’ or pooling of water.

Where more drainage is required, increase the total pitch from three up to five degrees. The use of an upstand –the requisite pitch and distance from the roof’s surface – can make successful installations much more easily achieved.

The specification of any rooflight must also take into account the maximum ‘flex’ or deflection allowed by the product – in other words, the maximum acceptable load applied by snow, wind or other physical weight – especially where glazing is fitted overhead.

In cases requiring a pitch greater than five degrees installers must utilise a structural kerb to support the skylight, placed perpendicularly to the roof.

Recommendations for internal walk-on skylights

Walk-on skylights within buildings are the exception to the rule regarding minimum pitch recommendations.

For safety purposes, these products must be as flush to the floor as possible. That means the ideal recommended pitch for walk-on skylights, whether internal or external, is zero.

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