Homeowners often ask whether a concrete lintel is stronger than a steel one, usually because a quote or a set of drawings names one and a neighbour used the other. The honest answer is that strength is not a property of the material alone. A lintel is chosen for a particular opening width, a particular load sitting above it and a particular wall build-up, and either material can be the right answer or the wrong one. This guide compares the two properly so you can follow the reasoning behind whatever your engineer or builder specifies.
What a lintel is actually doing
A lintel carries the masonry, floor joists or roof load above an opening and passes that weight down into the wall on either side. Its job is to stop the brickwork over the window or door from dropping or cracking. The load it sees depends on what sits above: a few courses of brick under the eaves is a very different situation from a full two-storey gable bearing down on a new patio door opening.
Precast concrete lintels
Concrete lintels are cast with steel reinforcement bars inside, because concrete on its own is strong when squeezed but weak when bent. The steel takes the tension along the underside and the concrete takes the compression on top. They are heavy, robust and tolerant of rough handling on site, and they suit solid walls and the inner leaf of cavity walls where a plain rectangular section can be built straight in.
- Good fire resistance and no risk of rusting through if kept dry
- Heavy to lift, which limits practical length for hand placing
- Plain section, so a separate cavity tray is normally needed in cavity walls
Pressed steel lintels
Steel lintels used in houses are usually galvanised folded sections shaped to bridge both leaves of a cavity wall at once, often with insulation already fitted inside the box. Because the shape does the work, a light steel section can carry a lot of weight for its size. They are quick to install and are the common choice over new windows and doors in modern cavity brickwork.
- Lighter to handle and place than an equivalent concrete unit
- Profiles made to suit specific cavity widths and loading cases
- Relies on its galvanised coating, so cut ends and damage need care
So which one is stronger?
Neither material wins outright. Both are manufactured to published load tables, and the right product is simply the one rated for the span and load in question. A concrete lintel with the correct reinforcement and a steel lintel of the correct profile can both do the same job safely. What matters far more is that the lintel is specified for the real loads, has enough bearing length on each side and is bedded properly. Most failures we see above openings come from undersized or badly seated lintels rather than from the choice of material.
When neither is the answer
Once an opening gets wide, or carries a floor or a roof as well as the wall, a standard lintel stops being suitable and a structural steel beam designed by an engineer takes over. That is typical where a rear wall is opened up for an extension or where a load-bearing internal wall comes out. Our separate guide on steel beams versus lintels covers where that line falls; this page is only about choosing between the two lintel materials.
Heat loss and damp details
In a cavity wall the lintel crosses the insulated gap, so it can become a cold bridge. Insulated steel lintels are designed to reduce that, while concrete lintels are normally used on the inner leaf with a separate outer support and a cavity tray over the top. Whichever is used, a properly lapped damp-proof tray with weep holes above the opening stops water running down the cavity and appearing as a damp patch over the window head.
How we decide on site
For new openings we work to the engineer's calculations and Building Control's requirements, and where no engineer is involved we check the loads and choose from the manufacturer's tables. On older solid-walled houses we often find timber or concrete lintels already in place, and part of the survey is judging whether they are fit to stay. If you are seeing cracking above an existing opening, that is a separate problem and worth having looked at before you pick any replacement.