Butterfly Roof-Material, slope, etc..

So we have taken the somewhat ill-concieved step of designing our new house with a butterfly roof. Has anyone else out there gone this route? If so, can you share your experience? Specifically, I am trying to figure out what to use for roofing that will both allow for a relatively low-slope as well as not break the bank. My research indicates the most metal roofing requires a 3 in 12 pitch, which is what we are at, but I would like to lower it in order to combat the tower-like effect in the living space from having a 15 ft peak. Also, crickets. How much slope is enough? I assume this is material dependant, which leads back to question 1. Thanks a lot for any advice you guys have to offer.

There are lots of choices for lower sloped roofs: torch down modified Bitumen (like Certainteed's Flintlastic), or a membrane like EPDM, TPO or PVC (see Johns Manville,www.jm.com). Any local installer is going to have an opinion about which is best for your job, but generally torch down will be the cheapest. As for crickets, I would try to keep the slope as steep as you can for piece of mind (like a 3:12 pitch), even though you can go as low as the recommended pitch for the crickets.

Thanks for the reply, The problem with the 3 in 12 pitch on the cricket is that it means that the cricket spans almost the entire roof: see attached imange. Sort of defeats the aesthetic of the butterfly design to have that big tent running across it. What about metal roofing? I have found some that only require a 1/4 in 12 slope. I have no idea on the cost of such things, but it inspires a bit more confidence than membrane in the valley. Thanks-

Of course, what is really bugging me about this is that I have seen this done before, and I wasn't paying attention at the time and now I need to know.

The Sunset Idea House from a couple of years ago has a very similar roof design to mine and I can't figure out how they are getting the water off.

I will pay good money if someone can give me a construction detail of that thing. 

I have attached some photos of the Sunset house, I wasn't paying attention to the roof at the time, so they aren't very good shots.  But you can see that there is no large 3:12 cricket bisecting the slope.

Any ideas?

Thanks- Josh

Here is a second photo, a little closer to the valley.

We used modified bitumen on our butterfly roof.  I'm not sure of the brand, but I can find out.  The main roof section is 1:12 pitch, and the two steeper sections are 2.5:12.  I'm not sure of the pitch for the cricket, but I think it's not very steep.  It's barely noticable when you're standing on the roof, let alone from the street.

Originally the roofers painted the bitumen with alumized reflective paint, like you might see on a commercial building for energy efficiency.  Quite a bit of our roof is visible from the street and the neighbors houses though, and the reflective paint didn't look so hot, so they covered it with tar and a very light colored gravel.  Not as energy efficient, but looks nice and matches the stucco.

http://vpizza.org/~jmeehan/gallery2/v/construction/20061107/IMG_1086.JPG.html
http://vpizza.org/~jmeehan/gallery2/v/construction/20070327/IMG_1227.JPG.html

Thanks! Good to see it in an actual application. I realize this may be asking too much, but can you tell me the sq ft cost?

You can also get it with a top coating that has ceramic granular bits embedded which is much like the surface of an asphalt shingle. You will still see the lap joints though as when its installed properly there should be a little bit of roofing cement exposed at the edge.

Nice house. Where is the location?

Reason I ask is aren't you worried about some over-speeding driver losing control at the turn? Or is it a private road?

I guess it does look like a rather poor location for a house in that second photo   But the street is a dead-end with only three houses on it, and I was standing in the turnaround at the end of the street when I took that photo.

Our house is in Oakland, CA.

Josh - I am currently building a home with a butterfly roof. Not only is it a butterfly, but it drains toward part of the house that intersects the roof. So you can imagine that I was quite concerned about water. I decided to go with a spray on polyurethane roof. Not only is it monolithic - there are no seams and they spray around all penetrations, so no flashing issues - but it also provides an R value of 6 per applied inch. After the poly is applied, they coat it with two layers of elastomeric coating, and then granules for traffic resistance. Five days after my roof was done, my framer dropped a 2x12 on the roof, leaving a pretty good size ding. But since the foam is closed-cell, unless the penetration goes all the way to the substrate, you are still leak free. It rained 3 days aftyer the ding incident, and I had no leaks. I'll get around to repairing it sometime... Additionally I had the roofer apply the foam about a foot up the wall that intersects the roof. I'll never have to worry about water penetration up there. Also, with a foam roof you can spray crickets rather than construct them from wood and substrate (within certain limits). Clearly, I would highly recommend it. -R.

Thanks for the foam idea, sounds like a great product. I am having a bit of a hard time finding a supplier in my area, but if I can track one down, I think I will give it some serious thought. Josh