Group of steel cavity lintels

Lintels: The new starter’s ultimate glossary

MarketingALL, Concrete Lintels, Steel Lintels Leave a Comment

Most builders and specifiers will be familiar with the terminology we use in the lintel trade. However, for anyone getting started within the housebuilding and construction industry this is our ultimate glossary of the terms, acronyms and general buzzwords we use so you if you are starting a new job, you can go in sounding like an expert!

Arch former

Stressline arch former 3D image

Arch formers are designed for use over openings in external walls.

Arch formers are used over openings in external walls and provide a low-cost solution to help form low rise brick arches.

Arch lintel

These come under our ‘specials’ category of lintels and arch lintels specifically are tailor-made steel lintels in an arch shape – designed to the provided specification.

Bay lintel

Like arch lintels, these are classed as ‘specials.’ These are specifically designed for bay windows.

Box Lintel

Box lintels are lintels where the metalwork forms a box shape. These include some of our internal solid wall lintels and external solid wall lintels. In most cases the box shape provides increased lintel strength.


Cavity walls are building walls made with two layers or skins. The skins are separated by a cavity in between. Cavity lintels are designed with a section of the lintel to fill the cavity, and in our case lintels have cavity sizes of between 50mm and 150mm to accommodate the different cavities in modern buildings.


This is a short term for what is called a channel lintel. These are ‘C’ shaped lintels that will take masonry within the channel.

Clear span

This refers to the width of an opening of a window or door. A clear span of 900mm is the gap in the wall. You will need a 1200mm lintel to accommodate for a 150mm bearing each side of the clear span.

Compressive strength

The Wikipedia definition is the “capacity of a material or structure to withstand loads tending to reduce size”. Find out more.


Stressline CXHD steel lintel

XHD lintels are among the strongest on the market. They can withstand extreme loading conditions.

This stands for ‘Composite Extra Heavy Duty’ and relates to our strongest type of cavity lintels.


A damp proof course or DPC is a layer of waterproof material used with lintels to prevent dampness and excessive moisture occurring.

Fair faced

Our fair faced concrete lintel is specifically designed with a smooth finish so that it can be applied in a highly visible area.

Fire rating

A fire rating is basically a fire resistance test result as output in a period of time. In context; our concrete lintels have a fire rating of 30 minutes.


Galvanised steel is a type of steel that has been prepared in a zinc coating to prevent rusting. Stressline’s steel lintels are pre-galvanised meaning they are galvanised before we bend and shape the steel.


This simply refers to a ‘heavy duty’ style lintel.


This is a type of ‘extra heavy duty’ lintel. See also XHD.


High-strength concrete lintels are designed for larger load bearing situations.


Hybrid lintels are speciality lintels with high thermal efficiencies but are generally very expensive and not as robust as standard steel lintels.

Inner leaf

This refers to the leaf of a steel lintel which will bear the weight of the inner part of the wall construction.


INT light duty internal solid wall lintel

SL100 INT and SL75 INT lintels are light-duty internal solid wall lintels.

This is a short code used for our light-duty internal solid wall lintels.


kN is KiloNewtons; a measurement of force used in lintel selection, and incidentally named after Sir Isaac Newton.


KiloNewtons per metre is the measurement of force not to be confused with kNm (see below). kN/m is what we use to measure the UDL.


This refers to kiloNewtons by metre or kN x m, also a measurement of force. This is what we use to measure the resistance moment.

Load ratio

Load ratios refer to the ratio of weight on each leaf of a steel lintel. You can find out more in our blog post about load span tables.

Load span

Lintel load span tables

Load span tables are used to calculate which lintel should be used for certain applications.

Load spans are the figures within the tables that help specifiers and those selecting lintels gather the information they need to choose the correct lintel.


This refers to a meter box style lintel, which is one of our single leaf lintels.

Outer leaf

The outer leaf refers to the section of a lintel which will bear the weight of the outside of the building, usually masonry.

Plaster key

This is a perforated base plate to help render the wall so the lintel is not seen.


This is a process that allows us to put strengthening wires within concrete lintels to improve their load bearing capabilities. All of our concrete lintels are prestressed.


Stressline R15 prestressed concrete lintel

The R15 is one of our most common lintels. It measures 100 x 140mm.

This is a common type of standard prestressed concrete lintel.


This is another common type of concrete lintel.


Red-oxide is the red paint finish used on our rolled steel lintels.


RM stands for resistance moment and relates to the amount of force a lintel can withstand without failure.


This is a short term for our rolled steel lintels; our strongest lintels in production.


This is a channel type of RS lintel. See channel for further information.

Serviceable load

This refers to the load that a lintel can safely bear. See also SWL.

Single leaf

This refers to a type of lintel with only one leaf like our single leaf external solid wall and our timber frame lintels.


Short outer leaf (SOL) lintels have an outer leaf of 75-100mm to accommodate decorative head detail or cant brick on the outside.


This refers to safe working load which is similar to serviceable load.

‘T’ Type

Stressline inverted 'T' style lintel

The inverted ‘T’ shape lintel is an external solid wall lintel.

This is the ‘T’ style or inverted ‘T’ style lintels within our external solid wall range of products.


TF is the short code for our timber frame lintels; specifically designed for timber frame wall construction.

Thermal break

This is a lintel with a physical break in the middle to enhance the thermal efficiency.


TR lintels are also known as tray lintels. These are part of our single leaf products.


This stands for uniform distributed load. This is similar to the SWL but is used for concrete lintels and refers to a load across an area i.e. kN/m as opposed to an SWL measure in kN.


Stressline 3D WIL lintel 3D image

This 3D image of a wide inner leaf shows the extended inner leaf holding blockwork

WIL lintels are wide inner leaf lintels which feature a wider leaf on the inner side – typically to support an inner load of 125-150mm of blockwork.


WOLs or wide outer leaf lintels have an outer leaf designed to support 125-150mm of stonework or blockwork.


This stands for extra heavy duty and refers to some of our strongest load-bearing lintels.

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