Why bifold door lintels are different
Bifold doors are often installed as part of a rear extension or open-plan renovation, as part of a project where a wide structural opening is being created, often in a load-bearing wall. That combination of longer span and heavy load above the opening sets bifold lintels apart from those used in standard door or window openings.
The longer the span, the more the lintel has to carry. As bifold openings frequently have floors, flat roofs or substantial brickwork sitting above them, the load category matters as much as the length. It is far less costly to choose the right lintel from the start than address structural problems after the doors are in and the renovation is complete.
For a detailed overview of how steel lintels perform in masonry cavity wall construction, visit our guide to steel lintel solutions for masonry cavity walls. Browse our entire range of lintels or contact our technical team for guidance before you order.
Types of bifold door lintels
Standard and medium duty cavity lintels
For bifold openings in walls carrying lighter loads, normally where there is no floor or roof structure directly above, a standard or medium duty cavity wall lintel will cover most residential applications. These lintels cover cavity widths from 50mm to 205mm, with multiple span lengths and load ratings to match the demands of your specific bifold opening. Check with our technical team prior to order
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Heavy duty and extra heavy-duty lintels
Where a bifold structural opening sits beneath a floor, flat roof or significant masonry, you need a heavy duty or extra heavy-duty specification. These lintels are built for the higher load categories that longer spans and loaded walls demand.
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Thermally broken lintels
Rear extensions and open-plan renovations that form part of the building's insulated fabric need to meet Part L building regulations. For bifold openings in these situations, a thermally broken lintel is what helps keep the installation compliant. Standard steel lintels create a path for heat to escape at the lintel position. Thermally broken lintels interrupt this with built-in insulation and no continuous steel through the lintel, which helps the extension meet current energy efficiency requirements.
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Span, bearing and load category: what to consider
Choosing the right Catnic lintel for bifold doors starts with three measurements: the span, the bearing and the load above the opening.
Span
The clear width of the bifold structural opening determines your minimum lintel length. Add 150mm on each side for the end bearing (the overlap onto solid masonry) to get the minimum total length you need.
Example: a 2400mm bifold opening requires a lintel of at least 2700mm.
Longer spans require careful consideration of load category. A lintel that is long enough but not rated for the load above it will not perform safely over time.
Bearing
Bifold openings often need increased bearing compared to standard doors. The wider the structural opening, the more important it is that the lintel rests on solid, level masonry with the right overlap on both sides. Our technical team can advise on bearing requirements for your specific wall construction.
Load category
The load above the structural opening determines which category of lintel you need:
• Standard or medium duty: wall load only, no floor or roof structure above
• Heavy duty: floor or flat roof load above the opening
• Extra heavy duty: significant structural loads, including heavy masonry or multi-storey construction above
Use the load tables on each product page to identify the right category or contact our experts for guidance.
For further help, read our Which lintel do I need? guide.
Installing a lintel above a bifold door opening
Bifold door lintel installation involves structural work within a load-bearing wall. If you are a homeowner overseeing the work, make sure you book a qualified builder or structural engineer to carry out the installation.
The wider the bifold structural opening, the more preparation the installation requires:
- Full-width propping: The wall above the complete span must be temporarily supported before any masonry is removed. A longer span means more props and a more extensive setup than a standard opening.
- Product checks before lifting: The lintel length, load category and orientation against the product datasheet should be confirmed before it goes in. Any mistakes are much harder to correct once the lintel is in position.
- Weight and handling: Lintels for longer bifold spans are considerably heavier than standard products, so extra labour or mechanical lifting equipment may be needed.
- Correct seating: The lintel must rest level on solid masonry on both sides with the minimum required bearing, so this must be checked before any brickwork is reinstated.
- Curing before loading: The mortar must reach sufficient strength before any props are removed and masonry above put back or built up.
Our installation guide covers the full process in detail. Visit our top tips for installing steel lintels before work begins.
FAQs about bifold door lintels
Load category depends on what sits above the structural opening. For a wall carrying its own weight only, a standard or medium duty product may be enough. However, where there is a floor, flat roof or significant brickwork above, a heavy duty or extra heavy-duty lintel is needed. Use the load tables on each product page or contact our technical team with your wall construction details and they can advise on the right category.
If the bifold opening is part of an extension or sits within the external thermal envelope of the building, a thermally broken lintel is an important part of meeting Part L building regulations. Standard steel lintels create a cold bridge at the lintel position and thermally broken lintels eliminate this with built-in insulation. If you are working with a builder or architect on an extension, check with them whether Part L compliance applies to your project.
Measure the clear width of the bifold structural opening. The lintel must overlap onto solid masonry by a minimum of 150mm on each side, so add 300mm to your opening measurement to arrive at the minimum lintel length. That gives your minimum lintel length. For example, a 2400mm opening needs a lintel of at least 2700mm. Length alone is not enough, so confirm the load category required for your wall construction before ordering. Our technical team can help if you are unsure.
A failing lintel above a bifold opening will often make itself known through cracking in the wall above, bowing masonry or the door panels becoming harder to operate over time. If you notice any of these signs, the first step is to have a structural engineer assess the cause before any remedial work is planned.
Replacement involves propping the wall across the full width of the opening, removing the failed lintel and installing a correctly specified replacement with the right bearing on both sides. Once the new lintel is in position, the masonry can be put back. This is not DIY work, so we recommend you appoint a qualified builder to carry it out.
In some cases, yes, but only if the product is correctly rated for the span and load involved. Many bifold installations need a heavier load category than a standard lintel provides, especially where the opening carries floor or roof loads above. Always check the load tables before ordering and contact our technical support team if the loading conditions are anything other than straightforward.
Both types bridge a structural opening and carry the load above it, but the key difference is span and load category. Bifold openings are normally a lot wider than standard door openings, which means the lintel covers a longer distance and often carries a greater load. This pushes most bifold specifications into a higher load category and longer lintel lengths than standard door products cover.
For standard door openings, visit our door lintels page. For window openings, explore our window lintels page.
See the full Catnic lintel range.
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