Lintels are a crucial part of any building project. Placed above doors, windows, and other openings, they carry the weight of the structure above, distributing loads safely across the walls. Without the right lintel in place, a building’s strength and stability can be compromised.
In this guide, we’ll look at the standard concrete lintel sizes you’re most likely to use, explore other lintel types such as box, angle, and cavity wall lintels, and share tips on how to select the correct size for your project. We’ll also provide practical advice on installation to help you achieve safe, professional results.
What Are Lintels and Why Are They Important?
A lintel is a horizontal support that sits above openings such as doors, windows, and archways. Its job is to carry the weight of the wall, roof, or floor above and transfer that load into the surrounding masonry. Without a lintel, the bricks or blocks over an opening would be left unsupported, leading to cracks, instability, or even collapse.
Choosing the right lintel is vital to ensure the structural integrity of the building. The correct size and type will distribute loads evenly, prevent damage to the walls, and provide a long-lasting solution that complies with building regulations.
Types of Lintels Explained
Lintels come in a variety of materials and designs, each suited to different applications. Understanding the options available helps you choose the most effective support for your project.
- Concrete lintels: A popular choice thanks to their strength, durability, and cost-effectiveness. Available in a range of sizes, they are ideal for both residential and commercial builds.
- Steel angle lintels: Typically used for lighter loads, often above small windows or door openings. Their simple design makes them easy to install, but less suitable for larger spans.
- Box lintels: Made from hollow steel, these are lightweight yet strong. They are commonly used where both strength and ease of handling are required.
- Cavity wall lintels: Specially designed to span cavity walls, supporting both the inner and outer leaves of masonry while allowing room for insulation.
Standard Concrete Lintel Sizes
Even when you choose the right type of caulk, the environment and application can make a big difference to how quickly it dries. Some of the key factors include:
Concrete lintels come in a range of standard dimensions suited for different spans and load requirements. Here are commonly used sizes and their typical applications:
- Width (Thickness) & Height (Depth): Standard lintels are often square – sizes like 4×4 inches, 6×6 inches, and occasionally 8×8 inches are widely used in residential construction.
Span Capacity: A 4-inch-thick lintel can span up to 12 feet, making it suitable for moderate-width openings.
Additionally, load-bearing capacity scales with size:
- A 4×8 inch lintel commonly supports around 1,500 lbs, making it suitable for smaller residential openings.
- A 6×8 inch option increases support to around 2,000 lbs, ideal for somewhat heavier loads.
For larger commercial openings, an 8×8 inch lintel can handle up to 2,500 lbs.
These standard options help ensure structural integrity without the need for bespoke sizing, saving time and cost while supporting safe construction.
| Lintel Sizes (inches) | Typical Span Capacity | Approx. Load Capacity | Common Applications |
| 4x4 | Up to 12ft | ~1,000 - 1,200 lbs | Small window or door openings in residential builds |
| 4x8 | Up to 12ft | ~1,500 lbs | Standard doors, medium window spans |
| 6x8 | Up to 12ft | ~2,000 lbs | Larger openings, heavier residential loads |
| 8x8 | Up to 12ft | ~2,500 lbs | Commercial openings, heavy-duty support |
Understanding Lintel Load Spans
When choosing a lintel, manufacturers provide load span tables to show how each product performs. These tables include several key values:
- Standard Lengths: This refers to the available lengths of a lintel. Lintels are typically produced in increments of 150mm. If the table shows 600 | 1200, it means the performance data applies to any lintel between 600mm and 1200mm in length.
- Nominal Height: The height of the lintel, given in millimetres (mm).
- Weight: The self-weight of the lintel, usually measured in kilograms per metre (kg/m).
- SWL (Safe Working Load): Sometimes called Serviceable Working Load. This figure, shown in kiloNewtons (kN), tells you the maximum load the lintel can safely carry.
- RM (Resistance Moment): Expressed in kiloNewton metres (kNm), this indicates the point at which the lintel would fail under load. While the technical details are best explained by an engineer, in simple terms, it’s the measure of the lintel’s overall bending strength.
By understanding these values, you can interpret load span tables with more confidence and choose a lintel that meets the demands of your project.
How to Choose the Right Lintel Size
Selecting the correct lintel size is crucial for ensuring both safety and longevity in any build. The main factor to consider is the span of the opening – the lintel needs to cover the full width of the window or door opening, plus a minimum end bearing (usually around 150mm on each side) to transfer loads safely into the surrounding masonry.
You’ll also need to think about the load above the opening. A small window may only need to support a few courses of brickwork, while larger spans beneath upper floors or roof structures will require deeper or reinforced lintels.
The type of wall construction is another important detail. Solid brick walls, cavity walls, and blockwork each have different structural requirements, and specific lintels are designed to suit them.
Finally, always refer to manufacturer guidance and building regulations when making your choice. These provide the tested load capacities and compliance standards you’ll need to follow.
Installation Tips
Fitting a lintel correctly is just as important as choosing the right size. Poor installation can weaken the support and cause long-term structural issues. Here are some key tips to follow:
- Check measurements first: Measure the opening carefully and make sure the lintel length allows for at least 150mm end bearing on each side.
- Prepare a solid base: Use padstones or engineer-approved supports beneath the ends of the lintel to spread the load evenly.
- Level the opening: Before placing the lintel, ensure the masonry is level and stable to avoid twisting or uneven stress.
- Handle with care: Concrete lintels are heavy. Use appropriate lifting equipment or get help to move and position them safely.
- Lay the lintel flat: Install with the correct orientation (some reinforced lintels are marked ‘TOP’ to show the right way up).
- Backfill and support: Once installed, carefully build masonry above, ensuring mortar joints are fully filled to lock the lintel in place.
By following these steps, you’ll ensure your lintel is properly supported, safe, and ready to carry the loads above it.
Getting the Right Lintel for the Job
Choosing the right lintel size and installing it correctly is essential for the strength, safety, and longevity of any building project. By understanding the different types, checking spans and loads, and following best practice installation, you can ensure your structure is properly supported.
Ready to get started? Explore our full range of concrete lintels, sign up for a Trade Account to unlock exclusive benefits, and visit your local branch for expert advice. Our team will help you choose the right lintel and the products you need to complete your project with confidence.