Required fall on flat roof for deck

Hi Everyone,

We are looking into building a new deck, and are looking into a flat roof. The roof will be insulated and the deck will be screened. The roof will start up at the roof line at roughly the height of the inside celing (i.e. the eves will be removed - it won't be one of those ones the joins the house under the eves).

What is the required fall of the roof? For example, I am trying to determine what the head height will be on the outermost side of the deck (i.e. not the house side) the deck goes out 4.5 meters, and whether we should consider another roof option if the head height gets too low.

Hope this makes sense. Hope someone can help.

Frog_hopper

The minimum fall required depends on the type of roof sheet you are using. Check the manufacturers website for details relating to your proposed sheet.

Tools

not sure without looking it up , but you want something with a steady flow ...to harsh a fall may overfill the gutterings capability to drain away, you have to consider the house roof sqr meterage as well as the pergola roof coverage ....this will all end up going down one gutter, you may have to allow for extra downpipes off the pegola to cope with it ...imagine a really heavy downpour .....would what you put in place cope?

ok thanks. Sounds like one for the building designer. Just wanted to try and get an idea before hand on whether we should try and go for a pitched roof design rather than a flat roof (coming off the hip of the gable at that end of the house).

Expect that the pitched roof (also insulated) would be much more expensive though but whether it is just a bit more, or whether it would be double the cost remains to be seen.

from memory minimum pitch for colourbond 4-5 degrees and for tray deck minimum pitch 1 degree