A header is a horizontal beam that crosses and supports the ends of joists, studs and rafters. Headers, which are located over doors, windows and wall openings, help distribute loads by transferring weight to parallel joists, studs or rafters. Headers are made out of strong, stiff materials, like steel or wood.
Sawn 2x8 or 2x10 lumber is commonly used to make headers. It’s strong enough to support most residential loads, it keeps the window tops at an even height and it costs less than steel or laminated veneers. However, while sawn lumber is a good choice for small window headers, it’s not as strong as laminated-veneer lumber or steel. According to Paul Fisette at the University of Massachusetts’ Building and Construction Technology Program, sawn lumber also limits design options.
Laminated-veneer lumber (LVL) and parallel-strand lumber (PSL) are engineered products that are made from wood veneers. These alternative lumbers are stronger than sawn wood and can be used in residential or commercial construction. Laminated veneer is almost completely free from warping and splitting and is often used in place of light steel beams or open web steel joists. Parallel-strand lumber can be used where longer-span headers are needed. Using laminated headers makes a framed wall stronger. You can make your own laminated beam by using construction adhesive to glue 2x6s on each side of a 1/2-inch piece of plywood. However, this kind of beam isn’t as strong as a “gluelam” beam used to replace a load-bearing wall.
Gluelam is glued laminated timber that can be used to construct commercial roof systems, bridges, ridge beams, complex arches and headers. Pound for pound, it’s stronger than steel, according to the Engineered Wood Association. Gluelam can be purchased in depths ranging from 6 to 72 inches or more and in lengths of up to 100 feet or longer. An alternative to glue-lam that some residential builders might want to consider involves sandwiching a piece of steel flashing in the center of the plywood-laminated beam described above. Use construction adhesive and bolt everything together in a diamond pattern to hold all the pieces together.
There are several advantages to using steel headers. Steel doesn’t split, shrink or warp. It’s resistant to rot, termites and mold, and it tends to be more uniform than wood. There’s less scrap because the quality of the steel is more consistent than wood. That translates into lower construction costs. However, steel headers need a lot of fastening, so working with it is more labor intensive. To solve this problem, engineers developed steel L-headers that don’t require as much cutting or fastening. Buildings that use steel L-headers instead of traditional box beam steel headers have more energy efficient walls because they’re easier to insulate. They’re also easy to install and don’t require skilled labor. However, unlike traditional box beam steel headers, L-headers should only be used in residential buildings subject to low to moderate wind speeds.
- US Department of Urban and Housing Development: Hybrid Wood and Steel Details – Builder’s Guide
- Umass Amherst: Calculating Loads on Headers and Beams
- NAHB Research Center: Steel L-Headers
- Backwoods Home Magazine: Five Building Tricks for Super Strong Framing
- Steel Framing Alliance: A Builder’s Guide to Steel Frame Construction
- The Engineered Wood Association: Glulam-Visible Beauty, Hidden Strength
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