For a porch roof the beam needs to be sized according to the maximum snow loads in your area and you must know enough about the porch design to determine how the load will be distributed and over what distance the beam will carry the load.
Header spans for covered porch roof.
Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.
The tables below give maximum spans for rafters and beams.
For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.
If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts.
In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts.
Build your patio cover or deck designing with roof rafter span tables board can span 16 ft for a wall pergola patio roof maximum beam rafter spanspatio roof beam calculatorpatio coversplease plete.
Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
A 4 by 10 can usually span up to 12 feet between posts.
Roof ceiling and one clear span floor 4 2x12 9 11 2 8 7 2 7 8 2 fccip 425 main st ste 25 greenfield ma 01301 3393 fccip staff phone.
Window door garage door headers supporting roof loads only.
Jan 15 2017 a simple buying guide for beams and rafters that support patio roofs.
Includes size and spacing tables for load bearing and links to related articles.
Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.
Tables providing size selections for various beam spans and loading combinations for southern pine dimension lumber and southern pine glued laminated timber are available for the following applications.
Window door garage door headers supporting roof wall floor loads.
In the example the beam spans the 10 foot width of the roof.