I decided to collect the question revenue....
EPDM is a film made from Ethylene/propylene/diene/terpolymer. It is
excellent for aging, water resistance, and water vapor transmission.
You may wish to read the article from the following source which makes
a stong case for heat welding on TPO's
The three films that are commonly used are PVC, EDPM, and TPO's. You
should consult with your roofing bidders as to which system will do
the best job for you on your building design.
As for the center drain, I think that is a mistake. (remember that I
am not a roofing expert so I bear no responsibility to the performance
of your roof...only the selected roofer can give you the best
consulting available) Where you place your drain should be
determined, in my opinion, as to where you are going to get hte most
sunlight. A drain in the middle of the roof that is not going to get
sunlight at the end of the winter will keep snow and water on your
roof for too long. I have a white roof with edge drains formed by a
slight roof pitch. Of course, I don't have a parapet nor do I have a
false ceiling above my catherdral pitches. Having the drains come
over the edge does result in icicles during the melting/freezing
cycles but I would worry about the snow/ice/water load if your drain
area was not in a place that would allow you to take maximum advantage
of the freeze thaw cycles.
I have 1 1/2" of fesco board insulation under the single membrane
roof layer. (my membrane layer is from Firestone)
Remember, Buckman, the most important decision is the selection of the
roofer. I had my roof put on over 12 years ago. After a storm this
past winter, a tree limb fell on the roof and put a hole through the
membrane. My wife and I were leaving at 7:00am the next morning on a
five week trip. I called the roofer from the airport before boarding
the plane. He was at the house later in the day and installed a patch
and charged me $75 for the work. To say I was pleased, is an
One problem I have had, is I did some renovation on the house after
the single membrane was put down. The same roofer applied the single
membrane to the newly renovated section of the house using the same
film from the same supplier. The color matched at first but after
about 8 years is beginning to show a difference in the shade of white.
Fortunatly, it is not visible from easy sightlines but only one angle
approaching the house from the back.
OK....I don't know if I have given you enough information to help with
your decisions. If you feel you need clarification on the information
I have supplied, please don't hesitate to request it. Thank you for
using Google Answers for this interesting construction question.
Search on Google: Firestone + roofing
Search on Google: EDPM + definition