A steel beam used as a lintel is one of the oldest and, at the same time, most precise solutions in structural engineering: It spans wall openings, supports the load above, and thereby creates the necessary conditions for windows, doors, and openings in load-bearing walls. Anyone who understands how a steel beam functions as a lintel, why it is chosen over other lintel solutions, and what must be considered during planning, installation, and detailing grasps a central intersection between structural engineering, building physics, and construction quality.
- What a lintel is in construction and what structural functions it performs
- Why steel beams are particularly common as lintels in solid-construction buildings, older buildings, and for retrofitted wall openings
- Which steel sections are used for lintels and how they are sized
- How a steel lintel is structurally installed: supports, embedment depth, and load distribution
- What building physics risks a steel lintel poses and how thermal bridges can be avoided
- What to consider when creating retrofitted wall openings with steel beams
- How steel lintels compare to precast concrete lintels, brick lintels, and wooden beams
- Which standards, design rules, and craftsmanship requirements apply
What is a lintel? Definition, function, and structural principles
In construction, a lintel is the load-bearing component that closes off the top of a wall opening and transfers the load above it to the side wall piers. The term derives from its function: the lintel “lints” the load around the opening. Without this component, the masonry above a window or door would give way under its own weight and the load from the floors above, closing the opening. The lintel is thus an indispensable element of any load-bearing wall with an opening, regardless of the wall’s building material.
Structurally, a lintel acts as a flexural beam. It is supported at both ends by the masonry and is subjected to stress in the middle by the load above it. This load consists of the dead weight of the masonry in the so-called compression arch above the opening, floor loads, roof loads, and, if applicable, additional loads from higher stories. Depending on the wall construction and the width of the opening, a significant portion of these loads can be transferred via the arch-bearing effect of the masonry, provided there is sufficient masonry above the lintel. In practice, this effect is taken into account during design, but it should not be assumed without careful consideration, especially when wall heights above the opening are low or when openings are located near building corners.
The support length of the lintel on the masonry is a critical factor. Support lengths that are too short lead to high local compressive stresses in the masonry, which can exceed its load-bearing capacity. Standards and regulations prescribe minimum support depths, which in practice are often specified as at least ten to fifteen centimeters on each side, with correspondingly greater depths required for heavier loads or softer masonry materials. The steel beam used as a lintel must therefore not only have sufficient load-bearing capacity itself but also ensure that the load is effectively transferred to the adjacent masonry.
Steel Beams as Lintels: Profile Types, Sizing, and Material Selection
Various steel sections are suitable for use as lintels. The most commonly used are rolled sections from the I-beam family and the IPE series (a standardized European I-section with parallel flanges), as well as the wider HEA and HEB sections. For smaller openings and lighter loads—such as door openings in interior walls—flat steel sections or U-sections are also used. For very wide openings or heavy loads, a single section may not be sufficient; in such cases, two or more beams are arranged side by side, or a composite beam is constructed.
The design of a steel beam as a lintel follows the rules of the steel construction standard; in Germany, this is DIN EN 1993 (Eurocode 3) in conjunction with the national application document. The basis is the verification of the bending capacity and the deflection under service loads. In practice, this means that a structural engineer determines the loads acting on the lintel, calculates the maximum bending moment, and selects a section with a sufficiently large moment of resistance. At the same time, a check is performed to ensure that the deflection under load remains within the permissible limits, as excessive deformation can lead to cracks in the adjacent masonry.
The steel used is typically structural steel of grade S235 or S355; S355, with its higher yield strength for the same profile size, can withstand greater loads and is therefore preferred in confined installation situations. Both grades are standardized according to DIN EN 10025 and are available from steel suppliers as rolled sections in standardized lengths. For installation in damp or corrosive environments, such as basements or industrial buildings, corrosion protection is essential: either through hot-dip galvanizing, suitable coating systems, or the use of stainless steel grades, which are, however, considerably more expensive.
Single Beams, Double Beams, and Composite Solutions
For single-shell walls, a single steel beam spanning the full wall width is sufficient in many cases. For double-skin exterior walls, such as those commonly found in modern residential construction with core insulation or curtain walls, the lintel must span the entire wall thickness, or two separate beams must be installed for the inner and outer skins. The latter solution is preferable from a building physics perspective because it maintains the thermal separation of the shells and minimizes thermal bridges. A continuous steel beam spanning the entire wall thickness, on the other hand, creates a direct metallic connection between the interior and exterior, which acts as a pronounced thermal bridge.
Composite lintels made of steel and concrete, in which the steel beam is embedded in a concrete body, combine the advantages of both materials: The steel absorbs the tensile forces in the tension zone, while the concrete absorbs the compressive forces in the compression zone and simultaneously protects the steel from corrosion and fire. Such composite solutions are common in precast construction but are also fabricated on-site. They require careful execution to ensure that the bond between the steel and concrete is truly effective.
Installation of a Steel Lintel: Supports, Load Transfer, and Construction Details
The installation of a steel beam as a lintel begins with the preparation of the supports. In new construction, the support surfaces are kept clear during masonry work, and the beam is installed before the masonry above it is continued. In the case of retrofit wall openings, the situation is more challenging: The beam must be installed into an existing, load-bearing wall without compromising the wall’s load-bearing capacity during the construction phase. This requires temporary shoring measures—so-called scaffolding or support structures—to bear the loads during installation.
The beam’s bearing surface on the masonry is typically leveled with a mortar bed to ensure even load distribution. In cases of high loads or soft masonry materials, steel plates or steel angles are installed as load-distribution elements to spread the concentrated support force over a larger area. Without these measures, local compressive stresses can develop in the masonry, leading to spalling or cracks. In practice, the support length should be chosen generously; the minimum structural requirement should be understood as a lower limit, not as a target value.
After installing the beam, the remaining gap between the top edge of the beam and the masonry is carefully filled. This step is crucial because an unfilled gap causes the beam to come into contact with the masonry not immediately, but only after settlement under load, which can lead to undesirable deformations and cracks in the masonry. The gap is filled with mortar or grout that has sufficient compressive strength. For beams with larger cross-sections and in tight installation situations, completely filling the gap is technically challenging and requires great care.
Building Physics Risks: Thermal Bridges, Condensation, and Corrosion
Steel conducts heat about fifty times better than masonry and several hundred times better than good thermal insulation. A steel beam used as a lintel that passes through the exterior wall without a thermal break is therefore a significant thermal bridge. On the inside of the lintel, the surface temperature can drop significantly below the room air temperature during the heating season, leading to condensation of moisture on the steel surface or on the adjacent masonry. Surfaces that remain damp over time promote mold growth and corrosion of the beam itself.
The solution from a building physics perspective lies in thermal separation. In double-shell exterior walls, as already mentioned, separate beams are installed for the inner and outer shells. In single-shell walls, the steel lintel can be clad on the interior side with a layer of thermal insulation that raises the surface temperature on the room side. Alternatively, steel lintels can be encased in concrete or clad with masonry, which at least mitigates the thermal bridge. In any case, the detailed design of the lintel should include a calculation of the temperature factor fRsi, which ensures that the interior wall surface does not drop below the dew point of the indoor air. DIN 4108 Part 2 defines the corresponding minimum requirements for thermal insulation in building construction.
Corrosion protection is an ongoing challenge for steel lintels. Although the lintel is protected from direct weathering when embedded in masonry, moisture from the masonry, condensation, or construction moisture can still reach the steel. Untreated structural steel rusts in humid environments, and rust expands: The volume of iron oxide is considerably greater than that of the original steel, which leads to explosive effects in the surrounding masonry. Visible rust spots and cracks along steel lintels in old buildings are a classic sign of damage resulting from inadequate corrosion protection at the time of installation. Before installation, the beam should therefore be coated with a suitable anti-corrosion paint; for particularly exposed locations, hot-dip galvanizing is the more reliable choice.
Retrofit Wall Openings with Steel Beams: Planning and Execution
Retrofitting a wall opening with the installation of a steel lintel is one of the most common modifications to existing structures. It is performed to connect rooms, create new doorways, open up kitchens, or restructure floor plans. In this context, distinguishing between load-bearing and non-load-bearing walls is fundamental. Non-load-bearing partition walls can generally be opened without a structural lintel; load-bearing walls, on the other hand, always require a professionally sized and installed lintel that safely transfers the loads.
Before any work is done on a load-bearing wall, a structural engineer must perform a structural assessment. The engineer determines which loads act on the wall, how large the planned opening may be, and what type of lintel is required. Without this assessment, cutting through a load-bearing wall poses a significant safety risk. In practice, such modifications are unfortunately sometimes carried out without structural verification, which can lead to settlement cracks, ceiling deflection, and, in the worst case, structural damage.
The retrofit installation follows a clear procedure:
- Structural assessment and sizing of the beam by a structural engineer
- Installation of temporary support structures to bear the load during the work
- Creation of support pockets in the masonry on both sides of the planned opening
- Insertion of the corrosion-protected steel beam into the support pockets
- Filling the support pockets with mortar or grout and leveling the gap between the beam and the masonry
- Allow the mortar to set before removing the temporary supports
- Creating the wall opening below the beam
The order of these steps is not arbitrary. In particular, the step of first installing the beam and only then creating the opening is critical to safety. If you create the opening first and then install the beam, you run the risk of uncontrolled load transfer throughout the entire installation process. For wide openings or heavy loads, the opening is often created in several sections to allow the temporary support structure to be adjusted step by step.
Comparison with Other Lintel Solutions: Concrete, Brick, and Wood
A steel beam used as a lintel is not the only solution, but one among several, each with its own strengths and weaknesses. Precast concrete lintels are widely used in new construction: They are cost-effective, available in standardized dimensions, easy to install, and can be designed with integrated thermal insulation layers to reduce the thermal bridge at the lintel if needed. Their disadvantage lies in their limited flexibility when dealing with unusual opening widths or heavy loads, as well as their comparatively high weight, which makes transportation and installation more difficult.
Brick lintels—that is, masonry lintels made of special lintel blocks or clinker bricks in an arched construction—have a long tradition in solid-wall construction. The masonry arch is one of the oldest lintel solutions in existence and transfers the load through compressive forces in the arch to the lateral abutments without generating tensile forces in the material. Modern brick lintel blocks are often combined with reinforcing steel embedded in concrete to also accommodate horizontal tensile forces. In terms of material properties, they blend seamlessly into the brick masonry and do not create a thermal bridge from a different material. Their disadvantage is the greater effort required for construction and their limited suitability for very wide openings.
Wooden beams used as lintels have a long history in historic timber construction and half-timbered buildings. In modern solid-construction buildings, they are rarely used anymore because wood swells, shrinks, and rots when exposed to constant moisture. However, wooden lintels are frequently encountered in the renovation of older buildings, and assessing them requires experience: A dry, well-preserved wooden lintel can last for centuries; a damp or pest-infested lintel, on the other hand, poses a serious safety risk. In the renovation of older buildings, steel beams have in many cases replaced wooden beams as lintels because they can support significantly more load while maintaining the same or a lower construction height.
The decision to use a steel lintel is typically made when large spans or heavy loads need to be supported, when the lintel’s height must be minimized, when retrofitting into an existing structure is required, or when precast concrete components in the required dimensions are not available. In the renovation of older buildings, a steel beam used as a lintel is often the most flexible and quickest solution because it can be cut to size on-site, installed using simple methods, and put into place without the need for complex formwork.
Steel Lintels in Context: Structural System, Detail Quality, and Design Responsibility
The steel beam used as a lintel is a seemingly small component, but one that is located at a critical point in the structural system. It connects the opening to the wall, steel to masonry, and the interior space to the outdoor climate. This is precisely why it is subject to structural, static, and building physics requirements that are often underestimated during the planning phase. An incorrectly sized or poorly installed lintel can lead to cracks, settlement, moisture damage, and, in extreme cases, structural damage that is far more expensive to repair than careful planning in advance.
Responsibility lies at several levels. The architect determines the opening geometry and the structural constraints. The structural engineer sizes the lintel and defines the installation details. The contractor implements these specifications with the care that a load-bearing component demands. Errors at any of these levels can undermine the work of the others. A correctly sized beam installed with supports that are too short is just as problematic as a correctly installed beam that is too weak for the actual loads.
The interface between the lintel and the thermal insulation design deserves special attention. In the energy-efficient retrofit of existing buildings, the lintel is often one of the last remaining thermal bridges after the walls, roof, and basement have already been insulated. Targeted insulation of the lintel area—whether through interior insulation boards, the installation of insulated lintel shells, or the structural separation of the shells—can significantly reduce heating requirements while simultaneously eliminating the risk of condensation on the interior side of the lintel. This measure is generally cost-effective in relation to its energy-saving and building physics benefits.
Ultimately, the steel beam serving as a lintel exemplifies a fundamental truth of construction: The quality of a building is determined not only by grand design gestures but by the sum of its details. A carefully planned, correctly installed, and structurally sound lintel is invisible because it works. It supports, it seals, it insulates, and it does so for decades without requiring any attention. That is precisely the goal of any good building structure.












