Do I need a lintel? A guide to lintel installation

Do I need a lintel? A guide to lintel installation

What is a lintel?

A lintel is a structural support over an opening, allowing loads to be transferred to the foundations without unnecessary stress placed upon frames such as windows or doors. A lintel should have sufficient strength and stiffness and be made of a material that is compatible with the masonry it supports. Commonly, lintels are made from the following materials:

  • Galvanised or stainless steel
  • Reinforced or prestressed concrete
  • Reinforced or prestressed masonry stone

Do I need a lintel?

Lintels are required for all openings over timber frames greater than 600mm in width, & for all openings over steel frames greater than 900mm. Often the specifications on the building plans will also state additional reinforcing measures such as steel rod through bed joints in subsequent courses of masonry above openings. This is to ensure that the masonry above becomes a solid mass, and adequately transfers load either side of the opening.

How are lintels installed?

Lintels are lifted into position whilst constructing brickwork, which may be done manually or by assistance of a crane. Usually a small gap is left above a window or door frame, to ensure that the lintel is supporting the load, as well as allowing for minor movements such as settlement of foundations or swelling of the frame itself. This is particularly applicable if timber frames are installed, as timber tends to swell or contract depending upon environmental factors such as moisture content or temperature.

When installing a lintel it is important to adhere to the following good practices:

  • Be careful not to chip the lintels coating – Corrosion protection is an essential component in ensuring that the lintel installed does not cause structural damage in the future. Moisture needs only the smallest of exposed area to penetrate, creating areas of rust and causing the lintel to expand.
  • The vertical leg of a steel lintel should always be the highest – Careful calculations are made off-site to ensure that the lintel provided is adequate to support the load above it. If the lintel is incorrectly installed, the lintel may no longer be able to support the load and may visibly deflect over time, causing loads to be place upon frames.
  • Brickwork should not overhang steel lintels by more than the allowable distance – Brickwork should not overhang lintels by more than 25mm, as a greater overhang may cause horizontal cracking to the brickwork above.
  • Brickwork should have mortar packing between brick & steel lintel – A mortar packing between the brick and the lintel ensures that the lintel does not twist whilst in service.
  • Adequate bearing should be achieved at either side of the lintel – A lintel will need a certain amount of cover or bearing either side of the opening that it supports. This is to ensure that the lintel does not deflect under the load that it is supporting.

Will my building inspector check that lintels are adequately installed?

Cap-It-All Building Inspections will check compliance of lintel installation at every plate height inspection.

Unfortunately at practical completion it is not possible to check all of the items above, as a building inspector will be unable to look down the cavity once the roof cover has been installed. Additionally, lintels are also required internally over certain openings, which will be unable to be assessed if all of your internal walls have already been plastered.

We have witnessed lintel non-compliance both internally and externally, so it is important to consider inspections at every stage of the building process. To view our building inspection prices as well as the savings that you can make by combining inspections, please visit our building inspection prices page.

Author: Lewis Flatt of Cap-It-All Building Inspections – Servicing the Perth Metro Area

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