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.
For secondary roof structural members supporting formed metal roofing the live load deflection shall not exceed l 150.
Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection.
These limits are based on live loads and activities experienced in specific rooms of a house.
Living room floors l 360 40 psf.
For the purpose of the determining deflection limits herein.
For structural roofing and siding made of formed metal sheets the total load deflection shall not exceed l 60.
For structural roofing and siding made of formed metal sheets the total load deflection shall not exceed l 60.
For secondary wall members supporting formed metal siding the design wind load deflection shall not exceed l 90.
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.
Typical deflection limits referenced in code books are l 360 l 240 or l 180.
This section deals specifically with the required live loading for aluminum canopies.
See the table below.
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.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
For secondary roof structural members supporting formed metal roofing the live load deflection shall not exceed l 150.
Both i codes just say floors 13 years ago.
I don t see any exception for decks or for floors which have different finishes on the underside.
For continuous aluminum structural members supporting edge of glass the total.
Bedrooms and habitable attic floors l 360 30 psf.
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.
B for cantilever members l shall be taken as twice the length of the cantilever.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
