Flat roof vs low pitch roof.

[leew2]

Currently thinking about building a rear extension for Project 2012. One thing I cannot decide on is wether to do a flat roof or a pitched roof. The problem with a pitched roof if that the steepest pitch I can get in is just 16.5 degrees due to presence of bedroom windows. I've seen tiles which will go to 17 degrees but not for 16.5 degrees. Because of this I have also considered using a GRP flat roof, this would have the advantage of allowing more headroom at the far end (to get the 16 degrees, I'd have to fit the rafters into the web of the RSJ over a Bifold door which is not ideal).
I cannot make my mind up over what type of roof to use. House is a typical inter-war semi, with an L-shaped rear, the extension would be next to the existing rear 2-story projection.

 

[simonjay]

Currently thinking about building a rear extension for Project 2012. One thing I cannot decide on is wether to do a flat roof or a pitched roof. The problem with a pitched roof if that the steepest pitch I can get in is just 16.5 degrees due to presence of bedroom windows. I've seen tiles which will go to 17 degrees but not for 16.5 degrees. Because of this I have also considered using a GRP flat roof, this would have the advantage of allowing more headroom at the far end (to get the 16 degrees, I'd have to fit the rafters into the web of the RSJ over a Bifold door which is not ideal).
I cannot make my mind up over what type of roof to use. House is a typical inter-war semi, with an L-shaped rear, the extension would be next to the existing rear 2-story projection.

Redland regent goes to 12.5 degrees, and forticrete centurion interlocking concrete tiles go down to 11 degrees.
Centurion have baffles to block rain driven underneath.

Simon.