Window Header: Size, Types, and Installation
What is a Window Header?
A window header is a structural beam that spans the top of a window opening, allowing the space below to remain open. It replaces a section of the exterior wall, maintaining structural integrity by supporting the weight above it.
Why is Correctly Sizing a Window Header Important?
Properly sizing the window header is crucial for several reasons:
- Window Operation: An incorrectly sized header can prevent windows from opening and closing smoothly.
- Structural Integrity: A header that is too small can lead to structural problems, potentially causing damage to the building.
- Weatherproofing: An undersized header may not provide adequate support for the window frame, leading to water leaks and drafts.
Common Window Header Sizes
The size of a window header depends on the span of the window opening. Common header sizes include:
- Two 2x4s: For windows spanning up to 3 feet
- Two 2x6s: For window spans of 4 feet, 6 inches
- Two 2x8s: For window spans of 5 feet, 9 inches
How to Determine the Appropriate Header Size for a Specific Window Span
To determine the correct header size for a window, you can use the following guidelines:
- For windows spanning 3 feet or less: Use two 2x4s or one 4×4.
- For windows spanning 4 feet, 6 inches or less: Increase the header size to two 2x6s.
- For windows spanning 5 feet, 9 inches or less: Use two 2x8s.
Factors that Can Change Header Sizes
Several factors can affect the size of a window header, including:
- Building Width: Narrower buildings require shorter header spans.
- Snow Load: Heavy snow accumulation can increase the weight on the header, requiring a larger size.
- Over-Building: Some builders may over-build headers for added caution, using thicker lumber or multiple layers.
How to Over-Build a Window Header
Over-building a window header can provide added strength and peace of mind. Common methods include:
- Using two 2x12s side-by-side for wide window openings or patio doors.
- Adding additional jack studs to support the header.
King and Jack Studs
Each window header requires two king studs and two jack studs. King studs are vertical supports that extend from the floor to the header. Jack studs are shorter studs that connect the header to the king studs. As window widths increase, additional jack studs may be necessary.
Laminated Veneer Lumber (LVL) for Window Headers
In addition to sawn lumber, laminated veneer lumber (LVL) can be used for window headers. LVL is created by gluing thin veneer layers together, resulting in a stronger and stiffer beam. LVL is particularly valuable for wide header spans, such as those for garage doors or french doors.
Installation of Window Headers
Window headers are typically installed as follows:
- King studs are secured to the floor and ceiling.
- Jack studs are attached to the king studs.
- The header is placed on top of the jack studs and secured with bolts or nails.
- The window frame is installed within the header opening.
- The header is insulated and covered with drywall or other finishing materials.
By understanding the importance of correctly sizing and installing window headers, you can ensure the structural integrity and weather resistance of your building while enhancing the functionality and aesthetic appeal of your windows.