Roof Slope & Asphalt Shingles

[CWLee]

(I posted this about 2-3 weeks ago, just as my campus server crashed. Usenet has been down (here) since then, so I don't know if this appeared or not, or if there were any responses.)

I'm aware of a common rule of thumb saying something like slopes less than 3 or 4 in 12 should not have shingles. I live in a development where all the homes are 25 years old. In the last 5 years several neighbors have replaced their roofs; even on slopes of 1 in 12 they have all used asphalt shingles, the same as the rest of their (steeper) roofs.

I plan to have my roof replaced this summer, and so far have been unable to learn of a code REQUIREMENT, in contrast to "general knowledge" about there being a minimum slope for asphalt shingles.

I'm located in Southern California, in an area that gets very little rain.

Any knowledge, advice, and/or insight appreciated.

[Grandpa Koca]

Its not necessarily a *code* requirement, but what the manufacturer will warranty; consult with them. Minimum slope is not just a leaking roof issue, its also wind resistance.

[tbasc]

International Residential Code Section 905 says in essence: Asphalt shingles on solid deck sloped between 2 in 12 & 4 in 12 requires shall have two layers of underlayment.

Ice & water shield is a good idea on slopes this shallow. TB

[borgunit]

you are correct, that is too low of a slope

[damn-spam]

[Borax]

I applied ashpalt shingles to my 2:12 sloped roof about 12 years ago. As posted above, the only code requirement was a double layer of felt. I live in an area with a moderate climate and had no problems.