There is no such thing as a good quality flat roof ;) Kidding ... kind of. Just don't believe people when they say flat roofs can be trouble free - having lived in a neighborhood full of them, I would respectfully beg to differ.

You can get the flat roof look with some slope, which I would highly, highly, highly recommend, unless you live in an area that gets no rain.

Don't forget to take into account higher homeowners insurance premiums for a flat roof. Ours was even going to require yearly inspections--yikes! We nixed the flat roof & went with peaked instead.

Hi,

Flat roof technology has come a long way and they are more problem free than before. I see that you are in Texas so you have hot summers. Do you get any snow? If you do then you need to allow for snow loading.

Most modern flat roofs are now built using EPDM. This is a sort of rubber mat which is use for swiming pools. The seams are sealed and bonded at instalation.

Most flat roofs are not strictly flat but have some pitch somewhere for draining. You do not want a mosquito pond on your roof.

I would recomend having as much pitch on the roof as possible. Often what looks cool about a flat roof visually is the "thin-edge" that "floats" the roof, especially if glass is used so that light is allowed to show underneath it. There are a number of ways to hide the drainage slope so that it looks like a contempoary flat thin roof when you are standing on the ground looking at the house. A view from above would however show the "cheating" and the sloped roof. It depends a bit on the site.

Hope this helps.

Best, Mike.

Good comments so far, thanks, but I am most interested on the COST issue. Can anyone answer that?

You'd be better off getting it figured both ways by someone who is in your area and can see your project up close and personal. If you are in an area where flat roofs are the exception, (most areas are), and they aren't experienced in proper construction, flashing, drainage, using a membrane on a flat roof, it shouldn't be considered. Only seek out reputable, experiencd contractors for your estimates.

Many design decisions should be made on the basis of cost but this is not one of them.

"I am most interested on the COST issue"

Cost is very local, so find some local folks to offer estimates.

That is about all you can do.

EPDM works great, but the major manufacturer does not pursue the residential market, they are interested in commercial applications (it take a lot more material).

Some areas have roofers that specialize in residential EPDM for flat (and almost flat) roofs.

Truly flat requires a lot of attention to drainage and the weight of retained water.
Even a slight pitch eliminates the retained water sealing and weight issues.

In most areas of the country, a flat roof will be more expensive because of the full EPDM membrane needed underneath the entire structure. It will also cost more to you in mistakes from the on the job learning experiences of the contractors you choose. Because of the slower water run, the framing for a flat roof has to carry more weight per square inch than that of any other type other than a tile or slate roof. You can't just decide in the middle of a build to have a flat roof versus a shed or gable, etc. It has to be designed correctly from the beginning as a whole system by a professional.

Great advice. Sounds like if I do this, I go for either as low a peaked roof as practical and get my contemporary look from other things, or maybe an almost flat roof.
Stinky tiger - your ID must have a story -- thanks, I do like your brother's work. Thanks all.