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How to size a header when framing a door opening

Answered by Brett Kulina ~ December 11, 2013 ~ No Comments » | Respond to this question

I'm installing a French door with sidelights in place of a 94 x 75in window. Door dimensions are 96 x 80. What size header do I need?

-Emily

Brett Kulina

Emily, when deciding what size header to install above your new French doors, you must first consider the size of the load being supported by the header and wall framing. For example, if you are installing the doors in an exterior bearing wall that is directly supporting the weight of the roof and possibly a second floor, then double 2 x 10s would be the bare minimum for a 96-inch opening. However, if that same size opening were in a non-weight bearing interior wall, or possibly even a non-weight bearing gable end wall with roof trusses above, then perhaps double 2 x 8s would be adequate. Of course, if there is a concentrated point load bearing directly on this header, such as an intersecting floor beam, then the opening may require a header made from double 2 x 12s or a engineered Glulam or a LVL beam.

If you are unable to positively identify the size of the load being supported by the new header, then you should hire an experienced carpenter or a structural engineer to determine the size of the header for you. After all, better to be safe then sorry when altering the structural integrity of your home's wall framing.

Because your new French doors will be installed inside an existing window opening, you may be able to gather some valuable information by examining the existing header, which will have to be removed to accommodate the taller dimensions of the new French doors. Perhaps your project is best accomplished by first removing the Sheetrock around the window opening and exposing the existing wall framing. This way you will be able to see what size the original header is and you can measure how much room there is below the wall's double top plate for the new header.

Another aspect of your project that bears serious consideration is how you will temporarily support the load above the existing header once that header is removed and the new header is installed. This challenge may be beyond your DIY skills and could require the help of an experienced carpenter. Don't assume that the load above the old window header will stay in place while you install the new door header!

If you need to familiarize yourself with simple header construction, then you should check out this diagram, which shows the main parts of a standard door header. You may also be able to gather some useful information at a local lumber yard that sells engineered wood products. Oftentimes the salesperson at the contractor's desk will be able to recommend a header size for you based on the species and quality of wood that they sell. Good luck with your project, and take it slow so you get it right the first time.

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