150mm cavity wall lintels are specified for projects with thicker insulation and cavities between 150 and 165mm. The cavities are typically full-filled, partial-filled (50mm residual cavity and insulation), or hybrid (10mm residual cavity and insulation).
Lintels are amongst the largest thermal bridges in a dwelling, and wider cavities require lintels designed for low-thermal-transmittance junctions – often with enhanced insulation continuity.
For more on this, read our guide to ‘understanding psi values - the thermal performance of lintels’ or, to determine the psi value for your lintel and window head detail in adherence with BR 497, use our Ψ psi value calculator.
Lintel bearing requirements depend on load, support material, and lintel type, in accordance with BS EN 845 2 and manufacturer load tables. Many projects adopt a 150mm bearing to support higher loads or improve buildability, but the correct bearing should always follow structural design guidance.
As new builds incorporate more insulation to meet stringent UK energy efficiency standards, 150mm cavities are increasingly common. Catnic 150mm cavity lintels are engineered to maintain insulation continuity and reduce heat loss through a high performance thermal break.
Read on to learn more about Catnic lintels for 150mm cavities and how to make an order.
Support & FAQs
Catnic lintels for 150mm cavities are available in a range of configurations to suit different masonry widths. The outer leaf dimension typically is 102mm brickwork, with inner leaf options from 100 to 140mm to accommodate blockwork variations.
While load class is one way to categorise lintels, wider cavities also require attention to thermal performance and insulation continuity. Catnic lintels are available in the following load capacities:
• Standard — Safe working load up to 26kN
• Heavy — Safe working load up to 48kN
• Extra heavy — Safe working load up to 60kN
• Extreme load — Safe working load up to 88kN
150mm cavity lintels come in standard, heavy, extra heavy and extreme load.
For guidance on cavity wall lintel selection, see our technical guide: Steel lintel solutions for masonry cavity walls.
Specifications vary across the Catnic range, including load capacity, thermal performance, insulation thickness, and compatibility with partial-fill or full-fill wall insulation. However, all 150mm cavity wall lintels are:
● Available in various materials and finishes - including powder-coated galvanised steel that is fully insulated with an integral plaster key.
● Available in multiple lengths – up to 4,800mm.
● Fully-filled - with CFC and HCFC-free insulation shaped to optimise thermal performance along the entire length, preventing cold spots.
● Certified - UKCA and CE marked to BS EN 845-2:2013, BBA certified, and made in the UK, Catnic 150mm cavity lintels are certified to BES 6001 Responsible Sourcing.
Browse our lintels online or request a lintel schedule - a concise document detailing dimensions, load tables, thermal performance, and pricing.
Catnic lintels feature Duplex corrosion protection for long term durability. Before installation, inspect the lintel for any damage and ensure the cavity is clear of debris. Prepare the opening by checking for damp, repointing mortar where necessary, and ensuring insulation is correctly positioned.
For wider cavities, maintenance should also include:
• Checking insulation has not bridged the cavity
• Ensuring the residual cavity remains unobstructed
• Confirming DPC trays and stop ends are correctly installed
A 100mm cavity wall lintel is designed for walls with a nominal 100mm cavity. A 150mm cavity wall lintel is intended for wider cavity wall construction, which allows for thicker insulation. Both 150mm and 100mm cavity wall lintel ranges have the same load capacity across the spans and, apart from the width of course, identical dimensions.
If you are unsure if you need a 100mm or 150mm cavity wall lintel, please consult our lintel selector tool.
While traditional open back cavity wall lintels provide excellent structural performance, we recommend thermally broken lintels for the same load capacity due to their significantly improved thermal performance. Catnic TBL lintels provide a one piece solution that is strong, easy to install, and engineered to minimise heat transfer.
If you're unsure which lintel you need, our technical team can help. Call 029 2033 7900 for all lintel enquiries. You can also use our lintel selector to quickly identify the correct product for your project using defined search parameters.
Catnic manufactures cavity wall lintels to suit a wide range of cavity widths — from 50mm up to 225mm — covering everything from standard and heavy to extra heavy-duty safe working loads, including the thermally broken range required for Part L 2021 and Future Homes Standard compliance.
Popular searches include:
• 100m cavity lintels
• 50mm cavity lintels
• We are the leading UK manufacturer.
• We were the first lintels manufacturer to achieve BES 6001 certification.
• All our lintels are BBA certified.
• Our steel is sustainably sourced and 100% recyclable.
• All our 150mm cavity wall lintels have Duplex Corrosion Protection System.
• We’ve been manufacturing trusted products since 1969.
• Our experienced customer service team is just a phone call away.
• We provide a free scheduling service.
• Many of our lintels are available for immediate purchase. Buy direct from Catnic here.
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Discover Thermally Broken Lintels
A unique design, providing a complete thermal break between inner and outer leafs with NO brackets, resulting in outstanding thermal performance always 0.05 W/mK or less.
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Video Guides
When selecting a lintel, there are three factors that should be considered to ensure the correct specification: the type of wall construction, the dimensions of the structural opening and the total load on the lintel. In this video, we run you through the lintel selection process.
Once you have chosen the correct lintel for your project, it is crucial that the lintel be installed properly – if it is not, it could lead to serious issues for the building. In this video, we explain the installation considerations for cavity wall lintels.
Catnic’s Thermally Broken Lintel is the only lintel on the market to provide a complete thermal break between the inner and outer leafs. In this video, we outline the key benefits of Thermally Broken Lintels and explain the installation process.
Steel lintels, and specifically Catnic's thermally broken lintels, have a significant role to play in reducing thermal bridging and achieving carbon gains. They represent one of the simplest and most economical ways for building fabric to be designed and constructed to help achieve the carbon gains necessary to meet current and future building regulations.
Lintel Resources
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