A lintel is a horizontal beam above an opening in a wall (such as a door or window) that supports the weight of the masonry above and transfers it to the sides. Without a lintel, the masonry above the opening would collapse. Every door and window opening in a load-bearing wall needs a lintel.
How does a lintel work?
A wall is strong under compression, but an opening breaks the load path. The lintel forms a bridge over the opening:
- The weight of the masonry above the opening presses down on the lintel
- The lintel transfers this force to the wall sections on either side of the opening (the jambs)
- The bearing length on each side must be at least 10 cm — more for heavier loads
Types of lintels
Concrete lintel (precast)
The most commonly used lintel in new builds. A prefabricated reinforced concrete beam. Available in standard sizes and easy to install.
Steel lintel
For large openings or heavy loads, a steel profile (U-section or I-beam) is used. Steel lintels are slimmer than concrete lintels for the same load capacity.
Brick lintel (soldier course)
An arch or straight row of bricks laid on edge above the opening. A traditional method, nowadays mainly decorative.
Timber lintel
In timber frame construction or lighter structures, a wooden beam is used as a lintel. Suitable for non-load-bearing walls or lighter constructions.
Lintel for a garage or renovation
When building a garage, the lintel is crucial:
- Garage door opening — A wide opening (often 2.4 to 3 metres) with a lot of masonry above. A strong lintel is essential here, often steel.
- Windows and pedestrian door — Smaller openings where a standard concrete lintel will suffice.
When renovating to break through or enlarge an opening in a wall:
1. First install temporary support (props)
2. Build in the new lintel with sufficient bearing
3. Only then remove the masonry below the lintel
4. Only remove the props once the mortar has cured
> Note: For load-bearing walls, a structural engineer must calculate the lintel. An undersized lintel can cause cracks in the wall or worse.
Choosing dimensions
The required size depends on:
- Width of the opening — The wider the opening, the stronger the lintel needs to be
- Load above — How much masonry or floor sits above the opening
- Type of wall — Cavity wall, half-brick or full-brick
Rule of thumb for a concrete lintel in a half-brick wall:
| Opening | Lintel size (indicative) |
|---|---|
| Up to 1.0 m | 100 x 65 mm |
| 1.0 – 1.5 m | 100 x 100 mm |
| 1.5 – 2.0 m | 100 x 135 mm |
| Above 2.0 m | Steel or structural calculation |
Common mistakes
- Insufficient bearing — The lintel must rest at least 10 cm on the wall on each side
- No lintel in internal wall — Internal walls can also be load-bearing. Always check.
- Lintel installed upside down — Some concrete lintels have a top and bottom. Check the marking.
Related terms
- Window/door frame
- Reveal dimension
- Soldier course
- Cavity wall
- Half-brick wall