100mm Cavity Wall Lintels

100mm cavity lintels were the standard size used in most homes during the late 20th century and early 2000s. While contemporary Building Regulations do not specify the “standard cavity size”, due to the focus on thermal performance of the building’s envelope, which led to a wide adoption of 150mm cavity for new builds, 100mm is still often used in plot-constrained sites and outbuildings. 

 

As a result, Catnic lintels for a 100mm cavity are an easy fit with standard wall tie lengths, coursing, DPC tray details and more. 

 

Our lintels are made of 100% recyclable, sustainably sourced steel to deliver reliable structural performance and corrosion protection. A single-piece structural solution, Catnic lintels have Duplex corrosion protection and CFC/HCFC-free insulation for improved thermal efficiency. 

 

We’re the UK’s leading manufacturer, and our lintels are backed by more than 55 years of experience.

 

Browse our full range of cavity wall lintels or buy direct today. 

CG50 lintel render

With today’s already high energy prices still rising, and growing inflation, poorly insulated dwellings translate directly into the bills of the homeowners. And, lintels are amongst the largest thermal bridges in a dwelling.

At Catnic, we have developed a range of thermally broken lintels (TBL), alongside our traditional cavity wall lintels. These reduce thermal bridging to the minimum and are offered for cavities between 90 and 205mm.

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.

Read on to learn more about 100mm cavity wall lintels from Catnic and discover answers to frequently asked questions

Support & FAQs

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

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.  

●    Available in various materials and finishes - including powder-coated galvanised steel that’s 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 100mm 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 for a 100mm cavity have a Duplex corrosion protection system to improve durability in situ. Once fitted into a wall, no ongoing maintenance is required. However, suitable pre-installation checks are needed.

Inspect the lintel for damage before fitting, and make sure the cavity is clear of debris. Prepare the opening by checking for signs of damp, repointing mortar where necessary, and confirming the insulation is correctly positioned.

Be sure to:
●    Ensure the insulation does not bridge the cavity.
●    Check that the residual cavity remains unobstructed.
●    Confirm DPC trays and stop ends have been fitted correctly.

The main difference between these two lintel ranges is the size of the cavity they stretch. Both 100mm and 150mm 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 of what size cavity wall lintel you need, please consult our lintel selector tool. 

To ensure you have the right lintel, get in touch with our technical team on 029 2033 7900 or use our lintel selector to quickly identify the correct product for your project using defined search parameters. 

Catnic manufactures cavity wall lintels across cavity widths spanning 50mm to 225mm, with safe working loads ranging from standard through heavy duty to extra heavy duty.

Popular searches include:

150m cavity lintels  

50mm cavity lintels  

●    We are the UK's leading manufacturer.
●    We were the first to achieve BES 6001 certification. 
●    All our lintels are BBA certified.
●    Our steel lintels are responsibly sourced and fully recyclable. 
●    All our 100mm cavity wall lintels have Duplex Corrosion Protection System.
●    We've been manufacturing since 1969. 
●    Our customer service team is just a phone call away. 
●    We offer a free scheduling service.
●    You can buy a wide selection of our lintels right away. Buy direct from Catnic here. 

  • Book a CPD

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Download Lintel Whitepaper

Unlock practical, up‑to‑date guidance on modern lintel specification. Three expert whitepapers cover thermal breaks, Part L & Future Homes Standard compliance, and best‑practice lintel design for today’s residential builds, giving you the clarity you need to specify with confidence

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What our customers think

  • “We have found the thermally broken lintels well-made, easy to work with and durable. Using thermally broken lintels on site has helped us to comply with the Building Regulation Part L requirements in a simple, straightforward manner”

    George Sowerby
    T.G Sowerby Developments Ltd

  • “I recently placed two orders with Catnic and I can honestly say from speaking to the rep Toby, all the way to transport their service and communication regarding the orders was superb!.”

    Dave Daniels
    Travis Perkins PLC

  • "Catnic has always been very quick and prompt in getting back to us when we ask for quotes and any problems we may come across. Very useful and easy to deal with! Excellent!"

    George Atkins
    Turnbull

  • “Catnic is a leader in its field, and the high quality of its TBL is testament to that. The team has been on hand at every stage of this project so far, offering technical support during the planning stages and now into the early stages of installation"

    Matt Taylor
    RBLI

  • "We have been using Catnic Lintels for over 10 years, they are by far the best. A superbly well organised company who offer exemplary service, their lintels are extremely capable and well suited to our high quality homes."

    Chris Dodge
    County and Coast Homes

  • “Catnic worked with our drawings and outlined exactly what we needed - including the structural loading measurements. Catnic is the only manufacturer that provides such a comprehensive scheduling service for free. It really is invaluable."

    Mike Parkinson
    Keyworker Homes

  • "Catnic is able to provide quality products according to the demands of the project at a competitive price"

    Steve Blythe
    Skanska

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.

Catnic thermally broken lintel installation

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.

Builder installed Catnic CG90/100 lintel

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.

Catnic TS90/100 lifted into position by builders

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.

Catnic balcony installation at kingsdown gate

Lintel Resources

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