Minimum pitch for three tag composition shingles.

[Lamar Bruce]

My first post. What is the minimum pitch for standard installation of three tab shingles? Next what must be done if pitch is less and same shingles are used? Finally, how can I tell what was done?
I'm told this is a place to get answers. Right?

[John Arnold]

Welcome Lamar!

From the 2003 IRC:

R905.2 Asphalt shingles. The installation of asphalt shingles shall comply with the provisions of this section.
- R905.2.1 Sheathing requirements. Asphalt shingles shall be fastened to solidly sheathed decks.
- R905.2.2 Slope. Asphalt shingles shall only be used on roof slopes of two units vertical in 12 units horizontal (2:12) or greater. For roof slopes from two units vertical in 12 units horizontal (2:12) up to four units vertical in 12 units horizontal (4:12), double underlayment application is required in accordance with Section R905.2.7.

[Scott Patterson]

My first post. What is the minimum pitch for standard installation of three tab shingles? Next what must be done if pitch is less and same shingles are used? Finally, how can I tell what was done?
I'm told this is a place to get answers. Right?

Lamar, are you a home inspector?

[John Arnold]

Sorry. Is it Lamar Bruce, or Bruce Lamar?

[Lamar Bruce]

Thanks. It's Lamar Bruce, Bruce Inspections, LLC in Taylors, SC. Thought this was right, but just needed confirmation. Thanks again.

[Rod Butler]

I am a practicing Mechanical Engineer in Utah.

The IRC may require 2;12 pitch but in areas of high snow loads and consistant freeze-thaw cycles this is considered less than adequate. Be sure to check local codes and ordinances.

:)