I live in a 26' x 32' cape in New England, where we get a lot of snow. We are planning to build a screened in porch on the eaves side of our house. The existing roof pitch is 45 degrees (12/12). My current design includes a 3/12 pitch. Do you think this will be sufficient? We have fiberglass shingles on our existing roof, but we were considering corrugated metal for the porch roof. Does the type of roofing matter? Thanks for your help.

Mark

A 3/12 pitch is too shallow for shingles, so you don't have that option. The only other 'asphalt' option would be rolled roofing. Not one of my favorites. Neither is the corrugated, but hey, that's my taste. There are other metal roofs out there, but they'll be more expensive, and this is only a screened porch.

Any way you can increase the pitch?

Throughout New England, there are thousands of houses with 12/12 roofs dropping onto 3/12 porch roofs. 4/12 is better and most manufactureers state either 3/12 or 4/12 as a minimum.

Simply doubling the underlaument is good insurance.

Corrugated metal is better for a barn or shed, IMO. The flashing to connect will be difficult.