Chapter 3 of the international residential code irc provides the maximum allowable deflection for a given structural member floor roof wall etc.
Ibc roof deflection limits.
Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection.
Examples of code prescribed deflection limits and live load values are.
Typical deflection limits referenced in code books are l 360 l 240 or l 180.
For structural roofing and siding made of formed metal sheets the total load deflection shall not exceed l 60.
In the 2015 ibc the body of table 1604 3 limits the deflection of exterior walls supporting plaster or stucco to l 360 with l being the span of the wall.
For secondary wall members supporting formed metal siding the design wind load deflection shall not exceed l 90.
The ibc which wouldn t apply to a sfr allows the greater deflection for roofs supporting non plaster finishes but like the irc it gives one deflection limit for floors period.
Bedrooms and habitable attic floors l 360 30 psf.
Both i codes just say floors 13 years ago.
For secondary roof structural members supporting formed metal roofing the live load deflection shall not exceed l 150.
For structural roofing and siding made of formed metal sheets the total load deflection shall not exceed l 60.
For aluminum structural members or panels used in roofs or walls of sunroom additions or patio covers not supporting edge of glass or sandwich panels the total load deflection shall not exceed l 60.
B for cantilever members l shall be taken as twice the length of the cantilever.
For continuous aluminum structural members supporting edge of glass the total.
For secondary roof structural members supporting formed metal roofing the live load deflection shall not exceed l 150.
For the purpose of the determining deflection limits herein.
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For structural roofing and siding made of formed metal sheets the total load deflection shall not exceed l 60 for secondary roof structural members supporting formed metal roofing the live load deflection shall not exceed l 150 for secondary wall members supporting formed metal siding the design wind load deflection shall not exceed l 90 for roofs this exception only applies when the.
I don t see any exception for decks or for floors which have different finishes on the underside.
See the table below.
Although it does not specifically name glazed components or assemblies or framing supporting glazing it does establish a deflection limit of l 240 for exterior walls supporting brittle finishes other than plaster or stucco.
