A header in construction is a short beam built into a wall above a door, window or other opening. It carries the load from the wall, floor or roof above across the opening and delivers it to studs on each side, so the opening does not sag or crack.
Headers are one of the most common structural members in a house and one of the most often undersized when someone widens a doorway. This guide explains how a header is framed, what the parts are called, how header sizes are read from a code table, when a wall does not need one, and the options when a wood header is not enough.
What a Header Does
In a wood-framed wall, studs carry load straight down from the top plate to the bottom plate. Cut an opening and the studs in that space are gone, so something has to pick up their share of the load and move it sideways. That is the header. It acts as a simple beam: loaded from above, supported at each end.
The load a header carries depends on what sits on the wall. A header in an exterior wall under a roof carries roof and ceiling loads; one in the first-floor wall of a two-story house also carries a floor and the wall above it. That is why the same opening width can need very different headers in different parts of the same house.
Parts of a Framed Opening
- Header: the beam over the opening. In houses it is often two pieces of 2x lumber set on edge with a spacer between them so the header matches the wall thickness.
- Jack studs (trimmers): shortened studs under each end of the header. They carry the header’s load to the bottom plate. Wider or more heavily loaded headers need two jacks per end instead of one.
- King studs: full-height studs nailed beside the jacks. They hold the header in place and stiffen the edge of the opening against wind.
- Cripple studs: short studs between the header and the top plate, and under a window sill.
- Rough sill: the flat member at the bottom of a window opening.
The City of Blaine, Minnesota framing tips guide (checked October 2026) shows this arrangement for openings in bearing walls: a header “sized per header table”, with single or double jack studs, full-height king studs at the outside edges and short cripples above.
How Header Sizes Are Read From a Code Table
For ordinary houses, header sizes come from tables in the International Residential Code (IRC) as adopted by your state or city. You enter the table with four things: what the wall supports (roof only, or roof plus one or two floors), the building width, the local snow load, and the lumber species and grade. The table returns the maximum opening width for each header build-up and the number of jack studs needed at each end.
Here is an excerpt from the exterior bearing wall header table in the Blaine guide, which is based on the 2015 Minnesota State Building Code and #2 hem-fir or spruce-pine-fir. The number in parentheses is the number of jack studs required at each end.
| Header | Roof and ceiling, 24 ft building width | Roof and ceiling, 32 ft building width | Roof, ceiling and one center-bearing floor, 24 ft width |
|---|---|---|---|
| 2-2×6 | 4-5 (1) | 3-11 (2) | 3-10 (2) |
| 2-2×8 | 5-7 (2) | 4-11 (2) | 4-10 (2) |
| 2-2×10 | 6-9 (2) | 5-11 (2) | 5-11 (2) |
| 2-2×12 | 7-10 (2) | 6-11 (2) | 6-11 (2) |
Read across a row and the pattern is clear: the same 2-2×10 header that spans 6-9 under a roof on a 24-foot-wide house drops to 5-11 when a floor is added on top. Two cautions apply. The Blaine table is written for Minnesota’s code and conditions, and the guide does not restate the snow load behind it, so do not lift these numbers for a house somewhere else. And anything outside the table, such as a point load from a girder landing on the header, a wider opening, or engineered lumber, needs a design. The same guide notes that engineered lumber “must be accompanied by engineering supporting their use.”
Walls That Do Not Need a Structural Header
A header is only needed where the wall carries load from above. In a non-load-bearing partition, or a gable-end wall where the roof framing runs parallel to it, the opening can be framed much more simply.
The Blaine guide allows a 2×4 laid flat, with no jack studs, for openings up to 8 feet wide in non-bearing or basement walls, provided the distance from the header to the plate above is not more than 24 inches. The US Department of Energy’s Building America Solution Center, in its guide to advanced framing insulated headers (checked October 2026), says structural headers are not needed on nonbearing walls, recommends a single flat 2×4 or 2×6 at the top of the rough opening, and suggests insulating the space above it like the rest of the wall.
The catch is knowing for sure that the wall is non-bearing. Our guide on how to tell if a wall is load bearing walks through the checks.
Insulated Headers on Exterior Walls
A solid lumber header is a weak spot in an insulated wall because wood insulates far less than the batts or foam around it. The same Building America guide lists options for load-bearing walls: prefabricated insulated headers, SIP headers, or a header made from plywood with rigid foam in between. It notes that ENERGY STAR requires the header to be insulated to at least R-3 in 2×4 walls and at least R-5 in thicker walls such as 2×6. It also suggests replacing jack studs with metal hangers on load-bearing walls, which leaves more room for insulation. Any substitute still has to meet the header strength requirement.
When a Wood Header Is Not Enough
Wide openings such as patio doors, garage doors and walls being opened up between rooms often exceed what built-up 2x lumber can span. The usual next steps are:
Engineered lumber
LVL and other engineered beams carry more load than sawn lumber of the same depth and come in long lengths. They are sized from the manufacturer’s tables or by an engineer.
Flitch beams
A steel plate bolted between wood members keeps the header the same depth as a wood one while adding a lot of stiffness. See our guide to the flitch beam for how they are built.
Steel beams
For the widest openings and heaviest loads, a steel beam is common, especially where a load-bearing wall is removed entirely. A light wide flange such as a W8x10 is 7.89 inches deep with a 3.94-inch flange and weighs 10 lb/ft, according to the AISC Shapes Database v16.0. A narrow flange like that can sit within the 5.5-inch actual width of a 2×6 wall, though the connections, bearing plates and posts all need design. Our article on removing a load-bearing wall covers how those projects usually go.
Header vs Lintel
The two words describe the same job. “Header” is the usual term in wood and light-gauge steel framing; “lintel” is the usual term in masonry, where a steel angle or precast concrete member carries brick or block over an opening. If you are working with a brick veneer or block wall, our steel lintel guide covers the sizes and bearing lengths used there.
Frequently Asked Questions
What size header do I need for a 36-inch door?
It depends on the load above and your local code table, not on the door alone. A 36-inch door has a rough opening a little wider than 3 feet. In a non-bearing wall a flat 2×4 can be enough; in a bearing wall, read the header table for your building width, snow load and the floors above.
Do interior walls need headers?
Only interior load-bearing walls need a structural header. Non-bearing partitions can use a single flat member over the opening.
What is the difference between a jack stud and a king stud?
The jack stud is cut short and sits under the header to carry its load. The king stud runs full height beside it from plate to plate.
Can I make an existing opening wider?
Usually, but the header has to be replaced with one sized for the new width, the wall above must be temporarily shored while you work, and most jurisdictions require a permit. In a bearing wall, a licensed structural engineer or the code table your building department accepts has to set the new header size.
Why do headers have a spacer between the boards?
Two 2x boards are 3 inches thick together, while a 2×4 wall is 3.5 inches. A half-inch spacer, often plywood, brings the header flush with both faces of the wall so drywall and sheathing lie flat.
Reference information only, not engineering advice. Disclaimer.