Installing a skylight on a flat roof
When installing a skylight on a flat roof make sure the product is not fitted completely flat itself. Glass inherently has a degree of flex when installed flat (as opposed to vertically as you would find in traditional windows and doors).
This is known as ‘deflection’ and means that without pitching the skylight up slightly at one end, rainwater will accumulate and begin to ‘pool’ on the glass. When this evaporates it can leave unsightly marks and stains behind.
Manufacturers therefore recommend a ‘minimum pitch’ to install their product so that rainwater and debris runs off the glass more effectively, keeping the skylight cleaner for longer.