Flat roof construction explained
Flat roof construction can be complicated. No roof should be completely flat. A flat roof should always drain towards a gutter or outlet.
A roof is considered a flat roof if it has a pitch of 10 degrees or less. Most flat roofs are Known to be problematic
and high maintenance. But with new innovations in waterproofing material such as
Other options include EPDM rubber roofing from Rubber bond which is a great roof for larger areas like supermarkets or industrial units but I prefer a liquid system like GRP for smaller domestic roofs which tend to have lots of detail such as, soil pipes. up-stands. and parapet walls,
Another thing to consider is,
Warm roof OR Cold roof
A warm flat roof is the best option in my opinion providing there is enough room for 100mm of insulation above the joists. pictured
In most flat roof constructions, there’s not much room to play with. You just don’t have the height needed for the insulation. some flat roofs will have parapet walls. Coping stone edging. Balcony doors or windows. with only 50mm up stands. as a result, the insulation must go underneath with a ventilation gap under the decking to eliminate the risk of condensation consequently, Condensation is a problem,
And can be a major problem with flat roofs. Not many cold roof constructions have enough vents for air movement between the joists you need to vent the moist air.
This is not the case with a warm roof.
warm roofs will have a thermal insulation layer above the structure with no cold areas for the warm air to condense.
therefore, theres no need for vents in this type of construction. my advice for your flat roof is a GRP fiberglass system with a 100mm insulation warm roof,