How steep of a roof must it be for a skylight?

Both skylights and roof windows are common options for letting natural light into a building, and skylights may also provide a number of other advantages including access to roof terraces and natural ventilation.

There are a number of factors to take into account when choosing a skylight or roof window, and the pitch of the roof may be one of them.

Drainage is impacted by roof slope, which also dictates how the units should be positioned and even the kinds of materials you may use. We’ll go through the various specifications for roof windows and skylights below, which should make it easier for you to choose the right product for your project.

Skylight installation on a flat roof

Make sure the skylight is not fitted fully flat when mounting it on a flat roof. Glass naturally flexes when it is mounted flat (as opposed to vertically as you would find in traditional windows and doors).

Without significantly tilting the skylight up at one end, rainfall will build up and start to “pool” on the glass. This is known as “deflection.” This has the potential to evaporate and leave behind ugly stains and markings.

Therefore, to ensure that rainfall and other debris wash off the glass more efficiently and keep the skylight cleaned for longer, manufacturers advise installing their products with a “minimum pitch.”

Skylight installation on a flat roof should be done at the required pitch

On flat roofs, there should be a minimum pitch or fall of 0.6 in 12 for many skylight uses. This is sufficient to make sure that water will drain off the glass’s surface and prevent pooling.

Although 0.6 in 12 is often the required minimum pitch, putting the unit somewhat higher, for example at 1 in 12, will be more successful. The greater the pitch, the better it is at draining off the water.

A curb is often built around the aperture in the roof to allow the slope into it that the skylight will be mechanically fastened to in order to achieve the requisite pitch. If you’re unclear, the skylight producer should provide drawings that show the minimum curb heights so that your builder can determine how high the slope’s top must be to accomplish the correct pitch.

But for safety reasons, walking skylights must have a flat pitch. Water will be able to drain off the unit with the aid of a 0.2 in 12 fall without creating much of an inclination.

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