How to Build Window Headers

April 12, 2015

Whether you are remodeling your existing home or building an addition it is important that your window openings are constructed properly. We will show you the easy steps you need to take to build window headers that are strong, stable, and durable. Adding large windows to a room will let the sunshine in and illuminate the area with natural light. But you must build window headers properly to make sure the main structure of the home doesn’t collapse or simply put undue stresses on the window itself.

Build Window Headers Like a Bridge

Think of the window opening as the span of a bridge. In particular, on very wide windows, you must bridge the gap between two distant wall studs. You must do so while still supporting the load above. The vertical supports of the header

(or bridge span) are normally simple 2×4 or 2×6 wall studs. The stud that reaches from floor to ceiling is called a “King Stud” while the inner support beneath the header is called a “Jack Stud.” If it was your first time trying to build window headers you may not think of installing a Jack Stud, not knowing any better. However, a Jack Stud is critical to the design and required by code.

How Big Should You Build Window Headers

Obviously the larger the span the larger the Window Header must be. That said, you MUST check with your local building code enforcement office to confirm the regulations for your area. You can also find information in the International Building Code Book, or on the FEMA website.

Here are the common wood sizes needed to build window headers for a given span:

  • Maximum Span 48” – 2×6 header
  • Maximum Span 60” – 2×8 header
  • Maximum Span 72” – 2×10 header
  • Maximum Span 84” – 2×12 header

NOTE: Consult your local building code office. Actual requirements may vary in certain areas of the country due to snow loads, wind loads, etc.

Header Material Alternatives

  • Dimensional Lumber: The most common headers are constructed using dimensional lumber such as 2×6, 2×8, or 2×10 material. In each case 2 pieces of wood are nailed together side by side and stood up on edge to bridge the span.
  • Engineered Lumber: In some cases an engineered lumber header is used. This is a solid piece of wood that may be 3-1/2” thick for a 2×4 studded wall or 5-1/2” thick for a 2×6 studded wall, with ample height to support the span.
  • Laminate Lumber: In this case the 3-1/2” or 5-1/2” wood pieces are stacked on top of each other and bonded together. The multiple layers would form a header that is 12” or more in height.
  • I-Beam Headers: For large spans such as a garage door opening it is common to purchase a prefabricated header. These are usually constructed using plywood for the vertical member, capped both top and bottom with 2×2 lumber. The gap between the plywood is filled with polystyrene foam for insulation value.

Contact Us:

If you think that trying to build window headers on your own seems like it may be more than you can handle give us a call. If you are searching for a professional contractor you can trust, to help you with your installation in Illinois: contact One Source Renovation, LLC at or give us a call at (815)-634-8922.