Internal Wall Lintels

An internal wall or door lintel is an affordable and high-performance way of supporting interior masonry constructions. Designed for the optimum blend of weight bearing and durability, these internal lintels are suitable for walls measuring 75mm to 140mm in width.

There is no need for the insulation of the internal steel lintel since heat cannot escape from inside the building’s thermal envelope.

From extra light to heavy-duty internal lintels, Catnic has your needs covered.

Catnic heavy duty box lintel for 100mm interior solid wall

Support & FAQs

Lintels for internal walls, as their name implies, are a type of structural component designed to be used within internal walls. They support the loads, such as masonry, floors, roofs and point loads above the openings on the inside of buildings.

Yes, absolutely. Catnic offers a range of internal wall lintels suitable for loadbearing walls for standard, heavy duty and extra heavy duty applications.

The lintel should have a 150 mm bearing on each end and be fully bedded on bricklaying mortar. The lintel should be levelled along the length and width. Floor or roof load should not be applied until the masonry cures.

Read more: From start to finish: How to install a Catnic lintel

The size of lintel you need is mainly determined by the structural opening span you have to cover, plus an additional 300 mm. This can vary from project to project, meaning accurate measurements are key to a successful installation.

Read more:Lintel size guide: How to specify lintel dimensions

Calculating the load imposed on lintels depends on a variety of factors, including the wall type in which the lintel is installed, and whether floor or roof loads need to be accounted for in addition to masonry loads.

Lintels are primarily designed to support uniformly distributed loads (UDLs), but on occasion, when point loads occur, they also need to be considered. This guide only provides an overview of how the loads on the lintel are established and should not be used as a substitute for obtaining loading calculations directly from the lintel manufacturer or a qualified structural engineer.

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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