A ‘Flat Roof’ has a minimal slope to allow water runoff (below 5 degrees) and would be weatherproofed using Bituminous, Asphalt, GRP, EPDM’s or Liquid Applied Solution.
Any Roof Lights installed to a Flat Roof system would usually involve an upstand/builders kerb and this will require the waterproofing up the side of the upstand height of 150mm.
An upstand or builders kerb can be built on site on Flat Roof using timber, concrete or metal but similarly can be purchased along with the Rooflight component to offer a total tested & manufactured system. Factory made upstands or builder’s kerb would normally be made from uPVC or aluminium. It is important to make sure they are thermally efficient thus limiting any positional issues with condensation.
The majority of Flat Roof Rooflights have either a glass or polycarbonate glazing. Glass & Polycarbonate have their own features & benefits as well as reasons to use one rather than the other. Glass will offer modern, clean aesthetics but polycarbonate will offer an economic value & longevity.
Ventilation options can be included within a Roof Light which can be an significant choice, as Failure to include this within your original plan may be expensive to re-install after the contract has been completed. Some local councils or clerk of works may require a minimal air-flow and they will direct you of this within their planning permission. Ventilation would normally follow two main options in either MANUAL or ELECTRICAL functions.