post and lintel

Post and lintel is the simplest structural system in building: vertical columns or posts carry horizontal beams called lintels across the space between them. The posts bear the load of the lintel and everything above it; the lintel bridges the gap and transfers that load down to the posts at each end. This is a direct, legible form of structural logic that has been used since ancient times, from Greek temples with stone columns to modern timber-frame houses.

The spanning distance between posts is the critical dimension. A lintel must be deep enough and made of material strong enough to resist bending across its span without excessive deflection. Wood lintels, typical in residential framing, might span 6 to 12 feet depending on load and timber grade. Steel beams or reinforced concrete can span much further, sometimes 30 feet or more, because they have higher bending strength. Stone lintels, used in masonry buildings, are rigid but brittle and fail suddenly under concentrated load; they typically span only 5 to 8 feet before the risk of breaking becomes unacceptable.

Where the system shows its limits

Post and lintel wastes interior space because posts must be placed at regular intervals to support the lintel. A floor plan with many columns is harder to arrange and lease. This is why frame structures with arches, trusses, or moment-resistant connections eventually replaced pure post and lintel in large buildings; they allow longer spans with fewer interior supports. However, post and lintel remains the default system for small buildings and is easy to understand, inspect, and repair because every structural action is visible.

The oldest variant is load-bearing masonry: solid walls of brick or stone act as posts, and stone or timber lintels run horizontally over openings such as doors and windows. This system is still common in renovation work and is valued for thermal mass and durability, though it is heavier and requires thicker walls than modern alternatives. Modern post and lintel typically uses timber studs in light-frame construction, or steel or concrete columns in commercial buildings.

Common failure modes are lintel sag (deflection under load that cracks plaster or causes doors to stick), rotting of timber lintels near poorly flashed window openings, corrosion of steel lintels exposed to water, and overloading a lintel that was designed for a lighter load before a renovation removed supporting walls. Wood lintels should be checked for moisture and insect damage during inspections; steel lintels need paint or other protection against rust.

The term itself is straightforward: a post is a vertical support, and a lintel (from Old French and Latin lintel, meaning threshold or beam) is the horizontal member above an opening. In masonry terminology, the lintel is specifically the beam that bridges a door or window opening in a wall; the term emphasizes its role in carrying the wall weight around that void rather than the lintel's generic structural function.