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Birdsmouth Cut | Rafter Notching Code Requirements

Rafter Notching Code Requirements

Fun Tip: To learn how to easily size roof rafter, be sure to check out this POST.

What is a Birdsmouth Cut?

Notches on Cantilevered Portions of Rafters

Notches on cantilevered portions of rafters are permitted provided the dimension of the remaining portion of the rafter is not less than 3-1/2 inches and the length of the cantilever does not exceed 24 inches in accordance with Figure R802.7.1.1.

Birdsmouth Cut

Can a Birdsmouth Cut be Used on All Roof Types?

Final Thoughts

This sums up the basic code requirements for notches on cantilevered potions of rafters that are subject to the International Residential Code (IRC). For more information on rafter notching subject to the 2021 International Residential Code, be sure to check out Section R802.7 of the IRC.

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About the Author

Building Code Trainer


This site is run and maintained by a Certified Building Official, Plans Examiner, and Inspector. With a Bachelors of Science Degree in Construction Engineering along with holding multiple ICC certifications, the Author of this site has over 15 years of experience within the construction industry.