How To Install A Lintel Above a Window

In the case of a window, a lintel is extremely important since it distributes the weight of anything above the window onto the surrounding wall instead of placing the weight onto the window frame.  Without a lintel above a window there is a danger of structural damage to a property.

The reasons for installing a lintel are to replace a bad lintel or when installing a new window in a wall to provide additional support to the load above.

The first signs of a problem with a lintel are usually cracks in the masonry above the windows and doors.  Spotting a problem such as hairline or more serious cracks in concrete lintels are normally a sign the lintel should be replaced.

Whether you are replacing an existing lintel or starting from scratch when fitting a new lintel, care must be taken to prevent damage to the existing structure above and to the sides of the opening.

Today, lintels are made of several different materials that are appropriate to the different compositions of walls in old as well as modern buildings. The materials which make up lintels include timber, concrete and steel.  The material chosen for the lintel may depend on the load which the lintel will support.

• cavity
• timber frame
• exterior solid
• internal partition
• load bearing

It is also necessary when fitting a lintel to consider the type of load:

• roof trusses
• masonry
• floor joists

When deciding which material you should choose for your lintel consider the following points:

• A wood lintel is usually found in older homes and can be susceptible to dry rot and insects.
• Brick should never be used alone as a lintel, they are usually supported with flat steel.
• Stone is sufficient for a small span but is poor under tension.
• Concrete with steel rods running through for strength is a better choice than stone or brick.
• One of the easiest lintels to work with is pressed and galvanized steel, which is good for both brick and wood frame walls.
• If steel lintels are being installed they should have a minimum end bearing of 150mm.  Steel lintels should be levelled and then bedded on mortar.  Levelling should be carried out along both the length and the width of the lintel.

Image Attribution: Wikimedia Commons.

It is important, prior to the start of lintel installation work, to discover if the wall in question is a load-bearing wall.

This determination is done either by pulling up the floorboards to discover which way the joists run, or by consulting with a structural engineer.

Note that it is important to check the direction of the joists along the whole wall, since a common refurbishment includes trimmer joists, which distribute a new load such as a stairway.

Step-by-step

1. To install a new lintel, determine the size of the structural opening and add a minimum of 150mm to each end.
2. Above the area of the lintel, install anchors and use acrow props to support wall as you remove masonry for the lintel.
3. Use a hammer and chisel to remove mortar around the bricks to be removed.
4. Once the mortar is removed, remove the bricks to make room for the new lintel.
5. A bed of mortar should be laid and the lintel installed.
6. The mortar needs to cure for at least two days before any other work can be done in the area of the new lintel.

Lintels are tough so if you need to drill into them you should consider using an SDS drill and drillbits.

It is important to note that installing a lintel involves structural work that may need approval from the building authority.

Your local planning portal will likely be able to advise you on regulations around installation of lintels to window and door frames.

The circumstances, weight of the load and whether the wall is a load bearing wall in the first place may all have a bearing on the restrictions and the need for authorisation required.

Moreover, determining whether a wall is load bearing can be tricky and it is certainly worth getting a professional opinion.