What are lintels?
A window lintel is a horizontal structural element installed above a window opening. Lintels over windows carry the weight of the wall above, including brickwork, blockwork and any loads from floors or the roof, and transfer it safely to the masonry on either side.
Without a correctly specified lintel for your window frame, the wall above can crack, bow or, in serious cases, fail. Choosing the right product, for a new build or a window lintel replacement, is essential for structural stability and long-term performance.
For a full overview, visit our guide to what is a window lintel.
Types of lintels
Steel lintels
Metal lintels are the most widely used option in UK construction. Hot-dip galvanised steel lintel products offer strength, durability and value, and are suitable for most standard domestic and light commercial applications.
Browse steel lintels
Cavity wall lintels
Cavity wall lintels span both the inner and outer leaf of a cavity wall and are the most common lintel for window openings in modern UK homes. Available in a range of cavity widths and load capacities to suit different wall constructions.
Discover cavity wall lintels
Single leaf lintels
Single leaf lintels support one leaf of masonry, the outer leaf, above a window opening. Available in standard and light duty options for a variety of applications.
Explore single leaf lintels
Thermally broken lintels
Thermally broken lintels feature integral insulation to minimise heat loss at the lintel position, the recommended choice for energy-efficient builds where cold bridging is a concern.
See thermally broken lintels
Stainless steel lintels
For coastal or aggressive environments, a steel lintel above a window made from austenitic stainless steel offers superior long-term corrosion resistance.
Browse stainless steel lintels
Bay window lintels
For more complex window configurations, Catnic also manufactures splayed bay window lintels and square bay window lintels to order. These are available on request and are tailored to your specific project requirements. Contact our technical team to request a quotation.
If you are looking for lintels for other openings, explore our door lintels and bifold door lintels ranges.
If you’re considering larger openings, read our guide to brightening your home with bigger windows and steel lintels
What size lintel for a window opening do I need?
The right lintel for your window opening depends on three factors:
• The width of the span
• The wall construction type (cavity, single leaf or solid)
• The load conditions the lintel needs to meet
Generally, the lintel around a window should extend a minimum of 150mm beyond each side of the opening, known as the end bearing. For most standard domestic windows, add 300mm to the clear opening width to calculate the minimum lintel length.
Example: a 1200mm wide window opening would usually need a lintel of at least 1500mm.
For larger window openings or those supporting floor or roof loads, you should consider bearing length and wall build-up before selecting a lintel. Contact our technical team for guidance on heavier-duty applications.
Check out Which lintel do I need? for further information.
FAQs about lintels for windows
A lintel is a horizontal structural beam that carries the load of the wall above an opening such as a window or door. Without a lintel for your window opening, the masonry above has nothing to support it, which can lead to cracking, bowing or structural failure. Every window opening in a load-bearing wall needs a correctly specified lintel.
Replacing a window lintel involves temporarily propping the wall above the opening, taking away the existing lintel and installing a new one in its place. The wall must stay adequately supported throughout the process to prevent movement or collapse. Once the new lintel is in position with the correct bearing on both sides, you can put the masonry back. Window lintel replacement is a structural task, and we recommend consulting a structural engineer or qualified builder before going ahead.
A lintel for a window frame is installed as part of the structural build, before the window frame is fitted. It sits in the masonry above the opening and carries the load of the wall above. Once the lintel is in place and the masonry has cured, the window frame can be fitted into the opening beneath. See our installation guidance for more details.
Door and window lintels work on the same principle as both are horizontal structural elements that carry the load of the wall above an opening. In many cases the same product can be used for both, as long as the correct size and load capacity is specified. Browse our full lintel range to find the right product for your opening.
Common signs that replacing window lintels may be necessary include cracking in the masonry above a window opening, bowing or bulging brickwork, or gaps appearing around the window frame. If you notice any of these signs, consult a structural engineer before carrying out any work, as the underlying cause should be investigated first.
For most standard domestic projects, a hot-dip galvanised steel lintel window product is the most cost-effective and widely used choice. For coastal or aggressive environments, a stainless steel lintel above the window is recommended in line with BS5628-3:2005. Thermally broken lintels are the best option when reducing cold bridging and improving energy efficiency is a priority. Contact our technical team for guidance on the right specification for your project.
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