A lintel is the structural member spanning a door or window opening, carrying the weight of the wall — and sometimes floor or roof loads — above it down to the jambs on either side. Choosing the wrong type, size or bearing length is one of the most common causes of cracking and settlement around openings. This guide covers the three materials you will encounter on UK domestic and light-commercial work: steel cavity lintels, prestressed concrete lintels, and natural stone.
Steel Cavity Lintels
Steel cavity lintels are the dominant choice on all cavity-wall construction built in the UK since the 1970s. They are pressed from galvanised mild steel (typically S250 grade after forming) and combine an inner leaf leg with an outer leaf leg in a single profile, bridging both leaves at once. The outer leg is shorter and set lower so it can support the face brickwork while the inner leg supports the blockwork inner leaf — the two legs are connected through the cavity, eliminating the need for separate single-leaf lintels.
Key manufacturers have standardised profiles to suit 50 mm, 75 mm and 100 mm cavity widths, and most are compatible with drip-edge insulation inserts to maintain continuity of the cavity board. Common profiles include:
- Standard duty (SD) — domestic openings, light loads, spans up to 1.2 m
- Heavy duty (HD) — spans up to 2.4 m, or where a floor joist bears within 225 mm of the opening
- Extra heavy duty (XHD) — spans over 2.4 m up to 4.8 m, or where a beam bears above
Galvanisation must meet BS EN ISO 1461 or the lintel must be hot-dip galvanised to a minimum coating of 600 g/m². All steel cavity lintels used in England and Wales must comply with BS EN 845-2 Specification for lintels.
Spans and Bearing
The total length of a steel lintel equals the clear span plus two bearing lengths. A minimum bearing of 150 mm each end is required under BS EN 845-2 for spans up to 1.8 m; increase to 215 mm each end for spans over 1.8 m. The clear span is measured between the faces of the supporting masonry, not the rough opening.
Prestressed Concrete Lintels
Prestressed concrete (PSC) lintels are precast units with high-tensile steel wires tensioned before the concrete sets. They suit single-leaf masonry (inner leaf only or solid wall construction), garage door openings, and internal partition walls. A standard domestic PSC lintel is 100 mm wide × 65 mm deep (matching a single brick course) or 100 × 140 mm (two courses) in the 100 mm width; wider units of 140 and 215 mm are available for solid brickwork.
Concrete grade is typically C40 or above. Prestressed strands are protected by the concrete cover, but lintels should not be used in aggressive exposure conditions (coastal or chemically contaminated environments) without specialist specification under BS 8500.
PSC lintels are heavier than steel — a 1.2 m unit weighs roughly 12–18 kg versus 4–8 kg for steel — which matters for manual handling on scaffold. They do not rust, require no cathodic protection, and are unaffected by the thermal bridging concerns associated with steel, making them suitable for high-performance low-energy builds where steel lintels are thermally broken by insulation.
Natural Stone Lintels
Stone lintels are a repair and heritage material rather than a primary structural choice on new build. They appear in pre-1920 solid stone or solid brick construction and must be matched to the local stone type (limestone, sandstone, granite) for aesthetic and structural compatibility. Natural stone lintels act in pure bending — there is no prestress — so their safe span is governed by the tensile strength of the stone, which is low: typically 2–5 N/mm² for sandstone versus 4–7 N/mm² for limestone.
For repair work under a Conservation Area or Listed Building consent, new stone is often cut to match the original. Reclaimed stone lintels are common at salvage yards and may show previous weathering or surface decay; always inspect for bed-face lamination before reuse.
Comparison Table
| Type | Typical cost (supply only) | Clear span range | Weight (1.2 m unit) | Key standard |
|---|---|---|---|---|
| Steel cavity lintel SD | £15–£40 | up to 1.2 m | 4–6 kg | BS EN 845-2 |
| Steel cavity lintel HD | £35–£80 | up to 2.4 m | 7–14 kg | BS EN 845-2 |
| Steel cavity lintel XHD | £80–£220 | up to 4.8 m | 15–35 kg | BS EN 845-2 |
| Prestressed concrete 100×65 | £10–£25 | up to 1.8 m | 12–16 kg | BS EN 845-2 / BS 8500 |
| Prestressed concrete 100×140 | £20–£50 | up to 2.4 m | 22–30 kg | BS EN 845-2 / BS 8500 |
| Natural stone (new cut) | £60–£200+ | up to ~1.5 m | 30–80 kg | Structural engineer’s scheme design |
Prices are supply-only ex-builders merchant, 2026. Install cost adds £30–£80 labour per lintel for a basic opening (more for structural alterations requiring acrow props).
Bearing and Padstones
Bearing length and the condition of the masonry beneath the bearing are as important as the lintel itself. Where loads are high or the masonry is weak (e.g. aerated-concrete blocks of 3.6 N/mm²), a padstone — a dense-concrete block or engineering brick — may be required to spread the point load. Padstone sizing should be calculated by the structural engineer; a common starting point is 215 × 100 × 100 mm dense-concrete padstone either side for a heavily loaded lintel.
Building Regulations
Lintel selection falls under Approved Document A (Structure). For domestic extensions and alterations, a structural engineer or a lintel supplier’s span table is normally sufficient evidence. Where the lintel carries more than a single storey of masonry, or where a new opening is formed in a loadbearing wall of an existing building, a structural engineer’s calculation should be commissioned and submitted with the Building Regulations application.
Thermal performance is covered by Approved Document L: steel lintels must incorporate a thermal break (usually EPS or mineral wool insert) to avoid creating a cold bridge that breaches the target fabric energy efficiency values. Most proprietary cavity lintels come with insulation inserts as standard — confirm this when ordering.
Practical Notes
- Order by clear span + 300 mm (two × 150 mm bearings) for openings up to 1.8 m; clear span + 430 mm for wider openings.
- Install steel lintels with the drip groove facing outward and downward on the outer leaf leg.
- Check the product’s load table before ordering; standard span tables assume typical domestic loading (one storey of 100 mm facing brick above). Where a joist or beam bears within 225 mm of the opening head, upgrade to HD or seek an engineer’s confirmation.
- Stainless-steel lintels are available for highly exposed coastal locations and are essential in Category 5 environments per BS EN 1996 (Eurocode 6 masonry).
