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Skylights in pitched roofs: What is the minimum pitch for rooflights in flat roofs?

3 July 2017
One of the most common questions we receive from clients looking to enhance their living and working space with an abundance of natural daylight centres around the correct pitch or minimum pitch for rooflights into a flat roof.

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As a recent industry report discussed, there is a growing trend for UK homeowners to improve and extend their existing properties rather than move and we’re experiencing an increased demand across residential and commercial installations alike.

Subsequently, we felt it was important to write an article that underlined the importance of installing your new rooflights at the correct pitch to ensure their long-term performance and stability.

While there is no definitive answer to the question, largely because of the diverse and varied range of rooflights available on the market, it’s still important to discuss, using our most traditional, timeless rooflights – the SkyView – as an example.

Recommended pitch

Ultimately, a fixed skylight such as the SkyView should be fitted into a flat roof at a minimum pitch of three degrees, as stipulated by current Building Regulations. This is the bare minimum required to guarantee that rain water will run off the surface of the rooflight and into gutters or drainpipes. Rooflights are a significant investment in your property; the last thing you want is to experience puddles forming on the glass surfaces as this can leave unpleasant marks and stains on the glazing, ruining the finish of your skylight.

There is no guarantee that individual droplets of water won’t remain on the surface of your skylight at a three-degree pitch following significant rainfall, but installation at this angle will ensure large forms of ‘ponding’ will not occur.

Throughout all forms of glazing, particularly with glazing installed overhead, there is an element of flex or ‘deflection’ involved in the manufacture and installation process. The specification of any new rooflight should take into consideration the maximum amount of flex it can take i.e. the heaviest amount of loading from wind, snow and physical weight. Without any pitch taken into consideration for the rooflight, the potential for water to pond will be that much greater.

Although the minimum recommended pitch for a flat roof skylight is three degrees, for property owners requiring more efficient drainage from their new rooflights, it is worth considering increasing the pitch of your new skylight to five degrees. This is easy to achieve by using your upstand to create the pitch required. An upstand plays an important role in ensuring your rooflight fits well. They are the frames a rooflight sits on, creating enough height from the roof surface and the necessary pitch for water run-off.

All warranties on non-walk-on Sunsquare rooflights are based on a five-degree pitch, so you can rest assured that the performance and safety of your new rooflight will never be compromised.

At Sunsquare, we also recommend all our rooflights are installed onto one of our optional upstands, which are machine-made and computer calculated in our state-of-the-art factory to ensure easy installation and optimum performance.

Should you wish to install a rooflight with a pitch of more than five degrees, the structural kerb must be manufactured and positioned perpendicular to the roof. This is to provide adequate structural support for the rooflight, ensuring the framework does not foul the external face of the kerb itself.

Pitch requirements for internal walk-on rooflights

If you’re looking to purchase an internal walk-on rooflight that encourages natural daylight into interiors below, such as basements or cellars, these type of rooflights are the exception to the rule when it comes to the minimum three degree pitch.

Naturally, interior walk-on rooflights are required to be as flush to the floor as possible for safety purposes. That’s why we recommend that all walk-on products for internal and external use, as well as pyramid skylights, must be installed completely flat, with zero pitch.

If you’re looking to push the boundaries of design and technology for your home, Sunsquare’s architectural rooflights are continually raising the bar for excellence in the UK rooflight industry. Our expert team can provide guidance and support to help you achieve new levels of natural light for your property’s interiors.

Simply call us today on 01284 848781 or drop us a line via our online contact form to discover the possibilities for your home.

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