Determining the header size for a load-bearing wall requires calculating the span length and the weight of the structure above (roof, second floor, and snow loads). The easiest method is to use prescriptive span tables from your local building department, which dictate standard sizes based on your home's layout.
The sizing steps are:
For a 6-foot span on a load-bearing wall, the required header size generally ranges from two 2x10s to two 2x12s, depending on the weight of the structure above. A common standard for a 6-foot opening supporting a roof and one additional floor is two 2x12s.
Back then, I used a rule of thumb for sizing headers that either someone had told me about or I'd read about somewhere. It went like this: Measure the span in feet and add 2 to that number. The sum will be the height of your double header in inches. For example, if the span is 4 feet, add 2 to 4 for a sum of 6.
Rule of thumb I learned is an 8 foot span needs a 2x10“ board. 10 needs a 12” and so on. A quick internet search for headers sizes may help you. You don't need a structural engineer.
Generally, a triple 2x12 beam can typically span up to 14 feet with uniformly distributed loads. If the triple 2x12 beam is constructed from #2 southern yellow pine and is supported by 2x4 studs or joists spaced 16 inches apart, the maximum load capacity for an 11 ft span is approximately 9,500 lbs.
A double 2x10 header (two 2x10s fastened together) can typically span between 8 and 12 feet without intermediate support for standard residential roof loads. Maximum spans depend heavily on the load (roof vs. floor), wood species, and local building codes, with some installations safely reaching 10–12 feet.
To give you the exact header size you need, I need to know what you are building. The term "header" applies to different projects; select yours below for exact specs:
A triple 2x8 wood header typically spans between 6 to 12 feet, depending on the weight it supports, the wood species, and local building codes. For basic applications, a reliable rule of thumb is that the maximum span in feet equals the depth of the header in inches multiplied by 1.51.51.5 (e.g., 8′′×1.5=12′ max).
A double 2x6 header can typically span between 3 to 6 feet without support, depending on the load it carries and local building codes. Builders often use a safe rule-of-thumb: 1 inch of header depth per foot of span (e.g., a 6-inch nominal header spans 6 feet).
For a 14-foot span, typical beam sizes range from a double or triple 2x12 (for light loads) to a 3.5" x 11.75" or 14" LVL (Engineered Wood). However, the exact size depends heavily on whether it supports a roof, a second floor, or just a ceiling, as well as the weight of the materials.
For a 16-foot load-bearing span, a common requirement is either a 3.5" x 11.75" LVL (Laminated Veneer Lumber) beam, a 4" x 16" Glulam, or a W8x18 Steel I-beam. However, the exact size depends strictly on the total weight (dead and live loads) being supported.
For a 7-foot span in a load-bearing wall, a common and safe header size is a double 𝟐×𝟏𝟐 or a double 1.75" ×cross× 11.25" LVL (Laminated Veneer Lumber), particularly if supporting a second story. For lighter loads, such as a single-story roof only, a double 𝟐×𝟏𝟎 may suffice, but a 2×12 provides better structural stability.
The size of a beam for a load-bearing wall depends on the clear span, the weight of the structure above (roof, second floor, snow load), and the material used. Generally, beam depths are 110one-tenth110 to 1121 over 12 end-fraction112 of the span length. A structural engineer is required to determine the exact, safe dimensions.
y Use the Joist Span table to find the acceptable joist sizes for a 12' span, 2x8s at 12” O.C., 2x10s at 16” O.C. or 2x12s at 24” O.C. Use the Beam Size table and find the 8' post spacing column. With a 12' deck span, the beam may be either two 2x8s or two 2x10s, depending on wood used.
A standard double 2x12 header can typically span between 6 to 16 feet, depending heavily on the supported load (e.g., roof vs. floor), the width of the building, snow loads, and the wood species.
A standard 2x8 dimensional lumber board cannot span 20 feet for structural applications like a floor or roof. The maximum unsupported span for a 2x8 under typical residential loads is around 12 to 14 feet, depending on the wood species and spacing.
The required size of a header depends entirely on its purpose. In construction, it depends on the span and load-bearing weight (e.g., standard bedroom windows up to 3′3 prime3′ use doubled 2×4s, while large patio doors often require 2×10s or 2×12s). For websites, a desktop header width is typically 102410241024 to 192019201920 pixels, with a height of 100100100 to 250250250 pixels.
The 4-1 headers usually have less back-pressure than the 4-2-1 header and customers have stated their cars seem louder at high RPM with the 4-1 headers. Most headers that are street legal or CARB legal are usually of the 4-2-1 design but there are exceptions.
Calculating the correct size for a construction header depends on the width of the opening, the weight it needs to support (roof, floors, snow loads), and building codes. For absolute structural safety, always consult a structural engineer or your local building department, as failure can lead to building collapse.
A double 2x8 load-bearing header typically spans between 3 to 6 feet for heavy loads (e.g., supporting a floor and roof) and up to 8–9 feet for lighter loads (e.g., roof-only). The exact distance depends on the header's height, wood species, and the weight of the structure above.
Yes, you can span 16 feet with a 2x10, but it depends on the lumber grade, spacing, and whether it is being used for a floor, roof, or ceiling.
To span 20 feet, the required beam size heavily depends on the load it carries and the material used. For most residential applications (like a roof, patio cover, or floor), a triple 1-3/4" × 11-7/8" LVL, a 3-1/2" × 15" Glulam, or a W8x18 Steel I-beam is typically required.