I feel steeper roofs are in general more desirable anywhere. A 6/12 in Florida helps keep the house cooler by helping the normal convective airflow in the summer. The downsides are more cost as you said and more danger to climb on.

We have a 4/12 hip roof with 3-1/2 foot overhangs on a prairie style house in Wisconsin and it holds up to snow just fine. We have trusses and they just engineer the snow loads into the truss design. I don't think it cost much more than a steeper roof would have cost, but don't know that for sure. It probably ends up costing less overall because I think you end up with less roof surface area and use fewer shingles, etc. There are several prairie style houses in my area with 4/12 roofs.

The cost of the framing is unlikely to be an issue.

In snow country with that pitch, I would strongly recommend covering the entire roof with WR Grace Ice & Water Shield underlayment. I even do that on 12/12 roofs in MA and ME.

Also, pay close attention to the potential for drifted snow loading at dormers, etc. Often it is not the amount of snow but repeated freeze-thaw cycles that causes trouble on a low-sloped shingled roof.

I've been an architect in MA for 38 years and in this climate I would only use a 4/12 pitch over an unheated space or open porch.

I would recommend the Shingle Style. I believe it is more elegant and more easily adapted to modern lifestyles. Even Frank Lloyd Wright used it for his own home.

Yeah- what mighy said :)

I thought the Ice and Water shield was standard these days, but I guess not.

We're also doing a 12/12 but our (very shallow) front porch is 6/12. I've seen too many neighbors out there with a long handle broom trying to sweep snow off the roof.

Mighty: I love Shingle (or Richardson Romanesque), but my better half isn't fond of shingles. (or castles) It'd have to be a shingle-style without the shingles. To compromise, I shifted to Craftsman, and now stumbled upon a couple pleasing Prairie designs. I'm skeptical of the 4/12 pitch (I'm in MA too) but Wright did most of his Prairie homes in the midwest, which probably get dumped on just as much as new england. And Prairie generally features deep eaves to shield against solar gain, and high celestory windows for air flow and light. Things that are coming back into mind with eco-friendly design. Wright was ahead of his time.

Ice & Water shield is something on my list, but I'm wondering if it's overkill if I go with a waterproof sheathing (AdvanTech) and spray foam to seal everything. It's probably not that expensive for a couple rolls, comparatively.

I did a development of remote cabins in the UP of Michigan which had to be designed for 300lb snowloads. Metal roofs, as you can imagine, are popular, but even with that, theres' so much buildup that sliding snow will easily shear off plumbing and heating vents, crush decks into unrecognizable splinters, and even kill people. Around where I live, it's about 80 (it depends on locale).

Where are you building and how much snow are we talking about?

I'd be building in mid New england, near MA/NH border. I'm not sure what any official snow load ratings are around here, but I've never had more than 20" of the wet heavy white stuff on my roof (6/16) at any given time. We do get a good amount of snow, but it's generally spaced out and has some melt in between. Maybe once or twice a season we'll get back-to-back-to-back storms. No lake or ocean effect to deal with.

If there is an official load requirement for roofs in my area, how would I find out? Is the difference in roof framing that much of a cost consideration that I should choose 6/12, 10,12, or 4/12?

Minimum design "Ground Snow Load" is contained in charts by cities & towns in the 7th edition of the MA State Building Code. The single family portion is published separately and taken primarily from the 2003 IRC but there are sections unique to MA. The code comes in a 3.5" thick loose-leaf binder and can be purchased at the state bookstore at the statehouse in Boston for $35. It can also be seen online at the link below.

Your location probably has the highest snow live load of 65 psf. For comparison Boston is 45 psf. If the dead load is 10 psf the total design load would be 75 psf. This number would be modified by roof slope, potential for drifted snow, etc.

This is not a big issue for a typical house design because the building code rafter design tables take into consideration the ground snow load.

As I mentioned before, in terms of waterproofing, the important issue is not the amount of snow but the extent of freeze-thaw cycles. Unless you have lived in snow country near the east coast you might not understand how destructive ice can be on a roof. You should use full coverage Ice & Water Shield roofing underlayment and put any gutters an inch below the projected plane of the roof surface.

Personally, I would consider the Prairie Style the least practical house design for northeastern MA. I've designed ski resorts in the Rockies and the Alps and built houses in VT, NH, and ME. Snow is never the problem; it's ice and poor detailing that destroys houses.

Wright might have been ahead of his time artistically speaking, but his stubborn, arrogant disdain for the practical aspects of building and the comfort of his clients is legendary. His houses were not only non-owner-friendly but were difficult to keep dry and warm and he didn't care. Personally, I think his net influence on the architecture of single family houses was negative.

Check out the Westhope house in Oklahoma for a good example of how not to design a house. This is the house where he told the owner to move his desk when informed by phone that the roof was leaking on it. The man's wife when moving pots and pans around the living room to catch roof leaks in the newly completed house is quoted as saying that "This is what we get for leaving a work of art out in the rain".

Here is a link that might be useful: MA State Building Code

I'm not bound to the Prairie style. Most of them I've seen I don't care for as a package. And the elements I do like (use of light, stone/wood exteriors, horizontal lines to lower the scale) could be incorporated into another style.

Re Wright, I'm reminded of stories of the Johnson Wax building leaking. And his use of experimental materials and techniques leaving some homes/buildings in a state of constant repair. Actually, many of his houses I find too boxy and cold.

I did have the mother of all ice dams the last couple years. First time in 20 years. In fact, I just reroofed and put ice & water shield halfway up.

I'm also wondering if insulating the under-surface of the roof (or using SIPS for the roof deck) would eliminate ice altogether by keeping heat from the roof in the first place. If no heat escapes, then the snow doesn't melt, right?

BTW, since you mentioned Shingle a few posts back, do you have any examples of moderate sized (2500-3k sq ft) Shingle style homes? The searches I've done all come up with palatial estate homes. Granted that Shingle-style really translates beautifully in a 7000 sq ft ocean side home, but I've yet to see something that really captures the details when scaled down.

"I'm also wondering if insulating the under-surface of the roof (or using SIPS for the roof deck) would eliminate ice altogether by keeping heat from the roof in the first place. If no heat escapes, then the snow doesn't melt, right? "

The pressure of heavy snow or sunny days can cause an ice build up even on a sip roof.( Ours is a sip roof) We do not have ice dams though.

As I said earlier, we have a 4/12 roof in Wisconsin and prairie style houses are very popular where we live and there are lots of 4/12 roofs here. Whether you like or don't like a prairie style is a matter of personal preference, and engineering has come a long way since FLW. You can check out the Westhope house in the link below--I believe it's the Richard Lloyd-Jones house in Oklahoma.

Here is a link that might be useful: FLW

I haven't done a Shingle Style house with less than 3,500 s.f., not because of the demands of the style but because of the owner's program needs.

The architectural style of a house isn't the hard part; it's solving the layout for the needs of a family for a given site within a budget. Most people who hire an architect are more demanding of the interior spaces than the exterior style or maybe it's just that there are more options available to a designer on the outside.

A "cold" roof can still suffer from ice dams for reasons such as a sunny day followed by a freeze, roof valleys and any other situation which interrupts water flow (e.g., vents). My main roof transitions from 11/12 to 4/12 and I definitely get ice build-up. Thanks to ice/water shield well up the steeper pitched roof my biggest issue is leakage around a vent on the flatter portion of the roof. I'm in the Adirondacks and the sun is the primary cause of my problems. It melts a little snow and then everything ices up at night when the temps drop as low as -25F.

Using ice/water shield on the entire roof may be a little pricey but is a good insurance policy. And Advantech is waterproof only for itself. Water enters a house through sheathing seams and penetrations and Advantech is not going to stop that.

Advantech is Huber's water-resistant OSB floor, wall & roof sheathing. Huber's Zip System is OSB sheathing with a waterproof vapor permeable coating with sealed joints.

Here is a link that might be useful: Zip System

Thanks MA. I did not know Advantech was a Huber product but I also see it is for flooring only. Probably nit-picky re the OP's terminology as the roofing system is still a Huber product. I did not see ice/water protection specifically mentioned but Huber does state the zip system meets IBC & IRC specs.