Window Header Framing Problems

As a building contractor it is my job to assembleA long time ago carpenters used a standard rule
the house to meet the specifications from theof thumb, you could go up two sizes larger than
architect and the structural engineer. I do this bythe window opening for your header. Let me give
looking at the building plans and installing theyou an example of what I'm trying to explain.
specified lumber sizes. I can take it upon myselfA 4 foot wide window opening would require a 4
to install a larger size wood beam or windowx 6 window header. A 6 foot window opening
header adding an additional cost to the job ofwould require a 4 x 8 window header. This should
course. I don't think so.give you an idea of what I mean by going up two
It's not uncommon for a framing contractor thatsizes larger than the window opening to figure out
has an additional 5 foot scrap piece of 4 x 8 leftthe lumber necessary to use for your window
over that he now has no use for. He can thenheader.
choose to use the 4 x 8 instead of a 4 x 6 forThis rule of thumb does not necessarily apply in
the window header. This type of building istoday's building industry. The reason for this is
common and acceptable.structural changes from earthquake damage. The
If the structural engineer calls out for 4 x 6structural requirements that are required for
window and door headers do not take it uponbuilding a home require a lot more metal bracing
yourself to replace the 4 x 6 with a 4 x 4. I haveand strapping. Therefore some of the lumber
seen too many framing contractors or carpentersrequirements for beam sizes and window headers
make an on-the-job judgment like this.will be different.
A good example would be a single story houseThis message is for general contractors, framing
with 2 foot wide windows that require a 4 x 6contractors and carpenters. When installing a
window header. As the carpenter builds homeswindow header and you take it upon yourself to
over the years he can come to his ownchange the size you also assume the responsibility
conclusion that a 4x4 will work fine for thisif the building fails. This type of mistake is
application. Again keep this in mind as a framingcommon and you guys know what I'm talking
contractor and a carpenter you are assemblingabout.
the home not designing it.It's not worth it. Keep in mind you are the
Do not change the sizes of any headers orassembler and not the designer of the building you
beams.are working on.