Header Size for a Window in a Weight-Bearing Wall

Considerations

• Header size has an important role in the window frame’s stability. The header, working in combination with other framing parts, helps transfer the weight bearing down on the window to the floor and foundation, reliving pressure on the window. A too-small header can press down upon the window and damage it. Improper header size leads to windows sticking and causes problems with the surrounding trim.

Complexity

• No easy way exists for calculating the exact header size needed for every window in a load-bearing wall. A range of variables, including the opening’s length; the weight the roof, walls and any floors above the opening; the house or structure’s width; whether the wall is an interior or exterior; and the wood species involved factor into the final determination, according to the Family Handyman Website.

Professional

• Due to complex nature of determining the proper header size for a specific window, consult a professional for assistance. Working with an architect or structural engineer can solve the problem because they can give you the correct size once they know the relevant information. If you're working with plans that were not created by an engineer or architect, consult the local building department.

Overbuild

• A work-around method for constructing headers without going through any complex formulas involves a process called overbuilding. Since most windows opening are less than 6 feet wide, a header that meets the code requirements for 6-foot wide windows also works for smaller windows. A header consisting of two 2-by-12-inch pieces of lumber with a one-half inch thick section of plywood in the middle provides solid support for the great majority of window frames built in residential construction.