A lintel above a door or window is a horizontal structural member that bridges the opening and carries the weight of the wall, floor, or roof above it. The lintel collects this load and transfers it down through its bearings into the masonry, framing, or columns on each side, keeping the opening from collapsing.

Builders also call this element a header, especially in North American timber framing, while masons and engineers tend to say lintel. The two words point to the same job: span a gap in a wall and redirect the downward force around it. Without one, the brick, block, or studs sitting over a door or window would have nothing to rest on, and the opening would crack, sag, or fail. The piece looks simple, yet its sizing, material, and bearing length decide whether an opening stays square for decades.

What does a lintel above a door or window actually do?

The job is load redirection. A wall transfers weight straight down to the foundation, but a door or window punches a hole in that path. The lintel spans the hole and reroutes the load that would have travelled through the missing section, splitting it toward the solid masonry or framing on either side of the opening. Those supporting zones are called the bearings.

Two forces act on the member at once. The top fibres are squeezed in compression, and the bottom fibres are stretched in tension. This is why material choice matters so much. Concrete and stone resist compression well but crack under tension, which is why a reinforced concrete lintel carries steel bars near its underside, exactly where the pull is strongest. Timber and steel handle both forces in a single piece, so they often span wider openings with a slimmer profile.

Above the lintel, masonry frequently forms a natural triangle of self-support known as the load triangle or arching action. Bricks bonded together tend to bridge a gap on their own, so the lintel may only carry the wedge of material directly above it plus any concentrated load like a floor joist or roof truss landing nearby. Engineers account for both the triangular dead load and any point loads when they size the member.

The main types of lintel by material

Material drives cost, span capacity, appearance, and how the opening gets detailed. Most projects pick from five families, and the choice usually follows the wall type around the opening.

Reinforced concrete lintels

Poured on site or precast in a yard, concrete lintels suit heavy masonry walls and longer spans. Steel reinforcing bars sit near the tension face, and the member can be cast to match the exact wall thickness. Precast units arrive ready to lift into place, which speeds up site work, while cast in place versions tie cleanly into surrounding concrete.

Steel lintels

Galvanised pressed steel and rolled sections such as angles or channels dominate cavity wall construction in the UK and parts of Europe. A steel lintel is slim, strong, and supports both the inner and outer leaf of a cavity wall while incorporating a damp tray. The Brick Industry Association notes that structural steel lintels for brick masonry are too critical to leave to rule of thumb sizing, so they should be designed for the actual load.

Timber and engineered wood headers

In wood framed houses the header over a door or window is built from dimensional lumber, often two members nailed together with a plywood spacer, or from engineered products like LVL and glulam for wider spans. Timber is light, easy to cut on site, and integrates directly with the surrounding studs and trimmers.

Stone and brick lintels

A single dressed stone or a course of bricks laid as a flat arch can serve as a lintel in traditional and heritage work. Brick lintels usually need hidden steel or a concrete backing for spans beyond about a metre, since brick alone is weak in tension. They remain popular where the visible face must read as continuous masonry.

Because window and door openings sit at the centre of this decision, getting the surrounding details right on your drawings matters. If you are setting out elevations and plans, a clean set of window CAD blocks helps you show opening widths and head heights accurately before the lintel schedule is fixed.

Comparing common lintel materials

The table below summarises how the main lintel families differ across the factors that usually decide a specification.

Material	Typical use	Span strength	Key trait
Reinforced concrete	Heavy masonry walls	High	Matches wall thickness, precast option
Steel	Cavity walls	High	Slim profile, built in damp tray
Timber / engineered wood	Wood framed walls	Medium to high	Light, easy on site cutting
Stone	Traditional masonry	Low to medium	Strong in compression, visible face
Brick	Short masonry openings	Low	Needs hidden steel for wider spans

How is a lintel sized for an opening?

Sizing answers three questions: how wide is the gap, how much weight sits above it, and which material carries that weight. The clear span sets the starting point, since a wider opening bends the member more and demands greater depth or a stronger material. Depth, not width, usually controls how far a lintel can reach, because a deeper section resists bending far better.

The load comes from everything stacked above: the masonry triangle, any floor or roof framing landing on that section of wall, and finishes. A door under a single storey carries less than a window directly beneath a roof truss. Engineers add these together, then select a member that limits deflection so finishes above do not crack. A typical serviceability limit keeps mid span sag to a small fraction of the span, often span divided by 360.

Wall thickness fixes the width. The lintel must fill the full thickness of the wall it sits in, so a 230 mm external brick wall takes a wider unit than a 115 mm internal partition. Cavity walls use combined lintels that bridge both leaves at once. Mixing these up leaves part of the wall above unsupported.

Site sequencing also shapes the choice. A precast concrete or steel lintel can be lifted into a partly built wall and the masonry simply continues over it, which keeps a crew moving. A cast in place concrete lintel needs formwork, reinforcement, a pour, and curing time before the wall above can be loaded, so it suits jobs where the lintel ties into a ring beam or slab anyway. For renovation work where an opening is being cut into an existing wall, the wall above must be propped on needles before the old material is removed and the new lintel is set on fresh bearings.

One more figure worth carrying in your head: the load the lintel sees is rarely the full rectangle of wall above it. For bonded masonry the triangular arching action means the member often carries only the wedge contained within an equilateral triangle rising from the bearings, plus anything that lands inside that triangle. Loads outside it largely arch around the opening. This is why a short opening in a tall wall can use a surprisingly modest lintel, while a wide opening near the top of a wall, where no triangle can form, needs a far stronger one.

Lintel vs header: are they the same thing?

For practical purposes, yes. Both terms describe the horizontal member over an opening that carries the load above. The naming splits along trade and region rather than function. Masonry and steel construction, and most British and international engineering practice, call it a lintel. Light timber framing, especially in the United States and Canada, calls it a header.

There is a subtle framing distinction worth knowing. In wood construction the header is the load carrying beam, while the short vertical studs that support its ends are jack studs or trimmers, and the studs running full height beside them are king studs. The header transfers its load down through the jack studs to the sole plate and on to the foundation. So the header is one part of a small assembly built specifically to hold an opening open.

A brief history of the lintel

The lintel is one of the oldest structural ideas in building. The post and lintel system, two uprights carrying a horizontal beam, appears across ancient cultures from Egyptian hypostyle halls to Greek temples, where stone lintels rested on columns to form the entablature. According to the structural definition of a lintel, an arch behaves as a curved lintel, which is how later builders spanned wider gaps once stone tension limits were understood.

Stonehenge shows how seriously early builders took the connection. English Heritage records that each lintel at Stonehenge is locked to its upright stones with mortise and tenon joints and to neighbouring lintels with tongue and groove joints, techniques borrowed from woodworking and cut into solid sarsen stone around 4,500 years ago. The continuous ring of lintels was even gently curved on its faces to read as a smooth circle of suspended stone.

How modern lintels handle cavity walls and energy performance

A lintel above a door or window is no longer only a structural piece. In a cavity wall it also manages water and heat. Steel cavity lintels carry both masonry leaves and include a sloped damp proof course that channels any moisture in the cavity out through weep holes, stopping water from tracking inside above the opening.

Thermal performance matters too, because a solid lintel can form a cold bridge where heat escapes around the opening. Manufacturers respond with insulated lintels that break the conductive path, and designers detail continuous insulation around heads and reveals. Guidance from bodies like SteelConstruction.info, backed by the British Constructional Steelwork Association and the Steel Construction Institute, treats fire, corrosion, and thermal detailing as part of the same specification rather than afterthoughts.

Technical specifications and span figures here are general guidance and should be verified by a licensed structural engineer for your specific project, wall build up, and local building code.

Putting It All Together

Quick Recap:

1. A lintel, or header in timber framing, spans a door or window opening and carries the wall load above it to the supports on each side.
2. It works by resisting bending, with compression at the top and tension at the bottom, which is why steel reinforcement sits near the underside of concrete lintels.
3. Material, clear span, load above, and wall thickness together decide the correct size and bearing length.
4. Modern cavity lintels also manage damp and thermal bridging, so the piece does structural and building physics work at once.