In brief: A steel lintel’s capacity depends on the exact lintel profile, span, cavity width, end bearing, and the loads above. The only safe way to confirm “how much” is to use the manufacturer’s published SWL/UDL tables for the specific lintel and, where required, structural engineer calculations.
If you’re looking for a broader overview — including the different types of lintels used in the UK and where each is typically specified — you may find our Complete Guide to Lintels in the UK useful.
How Much Weight Can a Steel Lintel Support?
Steel lintels are incredibly versatile and have excellent load-bearing capabilities. Depending on the lintel type, span, wall construction, and loading arrangement, standard duty lintels are typically rated for loads in the region of 20–25 kN, while heavy and extra-heavy duty lintels can be rated for significantly higher loads.
All load figures and spans referenced below are illustrative examples based on UK manufacturer data. Final lintel selection must always be confirmed against the specific manufacturer’s load tables and, where required, structural engineer calculations.
A steel lintel’s load capacity depends heavily on the clear span, cavity width, end bearing, and the dead and live loads acting on the wall above. Manufacturers such as Catnic, Birtley, Stressline, and Naylor publish detailed SWL and UDL charts for each lintel profile, which should always be used for specification.
Heavy Duty Steel Lintels
As a practical example, a heavy duty steel cavity lintel around 1050 mm in length will typically weigh in the region of 12–13 kg, depending on profile and cavity width. In common UK domestic external cavity wall applications, lintels of this size are often rated for loads in excess of 30 kN, subject to manufacturer data and loading assumptions.
Steel is also a cost-effective option where higher load capacity is required. Its favourable strength-to-weight ratio can reduce handling effort on site and, in some cases, reduce cumulative loadings transferred to foundations when compared with bulkier concrete alternatives.
At larger spans, for example around 2400 mm, heavy or extra-heavy duty steel lintels may still weigh comparatively little - often similar to one or two bags of cement — while being rated to carry substantially higher loads, provided the wall build-up, bearings, and loading conditions fall within the manufacturer’s published limits.
Steel Lintel Weight Limits
UK lintel charts list the SWL (Safe Working Load) for each lintel profile, expressed in kilonewtons (kN). This measures force, not simple material weight.
This distinction matters because buildings are subject to more than the dead weight of masonry. Live loads, wind loading, and variable occupancy loads all contribute to the forces acting on a lintel. For this reason, lintel capacity is always assessed using calculated loads rather than intuitive weight comparisons.
It’s also important to note that steel and concrete lintels behave differently under load. While this article focuses on steel lintels, concrete systems - such as those supplied by Stressline and Naylor - have their own span limits, bearing requirements, and load characteristics that must be read directly from the manufacturer’s guidance.
As a very broad visual reference, 1 kN represents roughly 100 kg of force under standard gravity, which is sometimes described as the weight of around 280 standard UK clay bricks. This comparison is illustrative only - structural loads are not assessed by counting bricks, and manufacturer load tables must always be used.
What Is the Weight Limit for a Steel Lintel?
Extra-heavy duty lintels are used where wider spans, higher masonry loads, or more demanding structural conditions are present. In manufacturer terminology, “extra heavy duty” typically indicates lintels designed to manage significantly higher loadings than standard duty profiles, rather than a fixed universal rating. Terminology such as “standard”, “heavy”, or “extra heavy duty” applies primarily to steel lintel ranges, and should not be assumed to map directly to concrete lintel classifications.
For example, manufacturer data shows that:
- Standard duty lintels are commonly used over typical domestic openings and may be rated for around 20–26 kN, depending on span and wall construction.
- Extra-heavy duty lintels can accommodate longer spans and higher UDL values, with ratings increasing accordingly when specified within published limits.
Lintel span charts also reference UDL (Uniformly Distributed Load), which represents an evenly spread load along the length of the lintel. Point loads or unusual load paths require separate assessment and should not be assumed to fall within standard lintel ratings.
Why Choose a Steel Lintel?
Steel lintels offer a high load capacity relative to their size and weight, making them particularly effective for external cavity walls where both inner and outer leaves impose different structural demands.
Modern thermally broken steel lintels are designed to maintain structural performance while supporting compliance with current thermal requirements, helping to maintain insulation continuity at the cavity head.
As spans increase, steel lintels generally become a more practical option than concrete alternatives, which can become bulky or impractical at larger openings.
References
- Catnic — Lintel Brochure (June 2024): steel lintel SWL, spans, and cavity lintel specifications PDF
- Birtley — Lintels Brochure (2019): structural load data and duty classifications for steel lintels PDF
- Stressline — Lintel Technical Guide (2022): span and load behaviour for concrete lintel systems PDF
- Naylor — Concrete Lintels Brochure (2025): specification data and load guidance for precast concrete lintels PDF
