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