Single storey extension: flat vs pitched roof?

[FranklinTheCat]

So we're planning a single storey extension and have finalised the floor plan (before or architect loses the will to live). Next question: the roof!

Architect favours a flat roof, or a partially flat roof - flat on the side adjoining the neighbouring semi, then pitched over the non-adjoining end of the extension. He's suggested putting a roof lantern in the flat bit.

We are twitchy about flat roofs. Our instinct is to go pitched.

This may be complicated by the fact that the adjoining semi has already extended (also single-storey) right up to the boundary. This could affect what we do with the roof, if we have to leave a gap between the properties.

Thoughts?

We have a parapit flat roof system with a lantern in. The parapit allows for the liner to go right up and under the coping stines. The roof has a 20 year guarantee and is edpm rubber like pond liner. It looks beautiful inside and out. Good luck with your build x

Stones not stines

I'm following with interest as I've been thinking the same. My house is 70 years old, original roof. 20 years isn't long really. BUT the design and how light works is a factor. I want a nearly 4m extension, with a single slope roof. That will mean a low pitch, it may not work at all.
Dual pitch won't be great if next door (semi) also extend. Flat seems the default, but if we do roof and rear extension insurance is more of a pain due to the amount of flat roof.

We're in the middle of a build, we've opted for a flat roof. The roof has a 1:40 slope, so water will run off easily.

We're just about to embark on a very small single story extension and have opted for a pitched roof for a few reasons. 1) even the best most technical flat roof has a bigger chance of leaking eventually and finding where the leak has come in could be harder with material that doesn't have a long history of use. 2) We'll be looking down at it from the first floor and looking over a slate pitched roof will be more attractive than onto a flat rubber or gravel one. (our neighbours have a flat roof and it looks terrible from above) and 3) We're having the inside of the ceiling at a pitch as well which will allow more light to come in from the velux in the roof. We're overlooked and will have minimal windows in the walls of the extension but a big fat skylight on an angle will make it light and bright.

oh, and 4) it's literally the only thing that DH and I agree on about this extension so when the Arch Technician tried to persuade meto go flat-roofed I had to say no.