Our building dept is citing code R 502.8.1 which says you cant cut more than 1/6 of the depth of a member. If my math is correct thats just under 2 inches into a 2 x 12.
How can you do a birdsmouth with that limitation ? I thought it was always 1/4
Our building dept is citing code R 502.8.1 which says you cant cut more than 1/6 of the depth of a member. If my math is correct thats just under 2 inches into a 2 x 12.
How can you do a birdsmouth with that limitation ? I thought it was always 1/4
Learn how synthetic panels can create watertight shower walls and tub surrounds — or a big problem.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Get home building tips, offers, and expert advice in your inbox
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial NowDig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now© 2025 Active Interest Media. All rights reserved.
Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.
Get home building tips, offers, and expert advice in your inbox
Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.
Start Your Free TrialGet complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.
Already a member? Log in
Replies
Notches at the ends of framing members can be up to 1/4 of depth. The 1/6 limitation is for notches outside the middle third of the span (no notches in middle third) that aren’t at the ends. Overhangs on rafters don’t count as part of the span.
When you say overhang for the 1/4 are the birdsmouth included?
R502.1.11 [IRC 502.8] Cutting, Drilling and Notching
is about floor joists.
R802.1.8.1.1 [IRC R802.7.1.1] Cantilevered Portions of Rafters
Is the better place to look for guidance on rafters and overhangs.
Ok great thanks