Most door frames that are 4 feet wide or less require a 2 by 6 header.
Garage door header span.
Between 4 and 5 feet the header should be built 2 inches wide and 8 inches long while a larger opening needs a header that is 2 by 12.
Notches on the outer thirds must not exceed 1 6 of the width of the board.
These details are based on testing done by the engineered wood association that included only simple span headers.
Measure the width of your door frame.
Both headers and girders are beams that are oriented horizontally and transfer load down to walls piers or posts.
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.
Their is no notching permitted in the center third of any beam.
Window door garage door headers supporting roof loads only.
To our knowledge no additional testing has been done to justify continuous headers over multiple garage door openings.