Replace a failed lintel or design a new one over your opening

Blueprint of a brick wall with two windows, a cracked old lintel on the left and a new steel lintel on the right

For homeowners with cracks or sagging above a door or window, or a new opening to support. Describe the problem and compare quotes from structural engineers who diagnose, design and specify the repair.

A lintel is the beam over a door or window that carries the brickwork above it. Older homes may have timber, stone or brick arches, and later ones have concrete or steel lintels. They fail in different ways: timber rots, steel rusts and can swell, and concrete can crack where its reinforcement corrodes. Cracks above an opening do point to the lintel in some cases, but not all, because other movement can cause them too. A structural engineer finds out which it is, specifies the replacement or new lintel, and sets out how the wall is held up while the old one comes out.

How a professional can help

Telling a failed lintel from other cracks: They look at the cracks around the opening, the line of the brickwork and the lintel itself where it can be seen, and judge whether it has failed or the cracks come from other movement.
Spotting rust, rot and decay: They check for rusting steel, rotten timber and cracked concrete, and for signs such as stepped cracks running from the corners of the opening or brickwork that has dropped above it.
Specifying the new lintel: They choose the lintel type and size, steel, concrete or a made-to-measure steel section, based on the span, the load above and the type of wall, instead of simply copying the old one.
Support while the old one comes out: They design the temporary support, such as props and needles through the wall, that holds up the brickwork while the failed lintel is cut out and the new one fitted.
Bearings, cavity trays and damp: They detail how far the lintel rests on the wall at each end, and the cavity tray and weep holes (small gaps that let water out) that keep damp from reaching it, since damp is a common cause of lintel decay.
New openings and heavy loads: For a new or wider opening, they check that a standard lintel suits the load, because a floor, beam or chimney bearing on it may call for something stronger.

Is this right for you?

You’ve noticed cracks or dropped brickwork above a door or window and want to know whether the lintel is the cause.
A survey or buyer’s report has flagged a corroded, cracked or missing lintel.
You’re cutting a new window or door into a wall and need the lintel specified for building control.
You’re replacing windows in an older house and have found timber or a rusting steel angle over the opening.

How the project usually runs

Inspection: The engineer looks at the opening inside and out, records the cracks and the condition of the brickwork, and uncovers the lintel in a small area if its type and condition aren’t visible.
Findings and options: You’re told whether the lintel is the cause, how serious it is and what the options are: repair, replacement, or leaving it and monitoring the cracks for a while.
Design and specification: The new lintel, its bearings, the temporary support and the damp-proofing details are specified, with a drawing and calculations if building control needs them.
Notices and approvals: Where the work is structural, building control is told. If the wall is shared with a neighbour, a party wall surveyor can say whether notices are needed, in England and Wales.
Replacement on site: The builder props the wall, takes out the old lintel in sections and fits the new one on proper bearings with a cavity tray. The engineer can check the bearings and tray before the brickwork is rebuilt around them.

What affects the cost

The number of openings affected and how wide they are.
Whether the old lintel is easy to reach, or hidden behind plaster, render or a bay.
The type of lintel chosen, and any made-to-fit sections for wide or heavy openings.
How much temporary support and brickwork rebuilding the job needs.
Whether the cracking has other causes, such as movement in the walls, that need to be investigated first.
Making good brickwork, plaster, render and windows after the replacement.

Building control and lintel work

Replacing a lintel is repair work, but it is structural, so ask building control whether it needs notice or approval where you live. The answer can differ between England, Scotland, Wales and Northern Ireland, and structural engineers work across the UK.
A new opening in a wall needs Building Regulations approval, or a building warrant in Scotland, and building control normally expects the lintel to be specified.
In a listed building, replacing historic lintels can need listed building consent, because they are part of its character.
In England and Wales, the Party Wall etc. Act 1996 can apply if the lintel is in a wall shared with a neighbour.

Questions people ask

Are cracks above my window a sign that the lintel has failed?

Sometimes, but not always. Stepped cracks rising from the corners, brickwork that has dipped above the opening, or visible rust or rot can point to the lintel. Other cracks come from movement elsewhere in the wall or the building. An engineer can look at the pattern and tell you which it is before you spend money on replacement.

Why do steel lintels rust?

Steel lintels that were not galvanised (coated in zinc) or otherwise protected can rust if damp reaches them. As steel rusts it swells, which can push the brickwork apart and crack the mortar joints above the opening. Replacing it with a protected lintel and a proper cavity tray to keep water away is a common repair.

Can I replace a lintel with a general builder?

A lintel carries the brickwork, and sometimes floors, above it, so the wall must be properly propped while it is out. A builder experienced in this work can do it, but the new lintel and the propping should be specified by an engineer, particularly where a floor, beam or chimney sits above.

Do I need a lintel for every new window?

Every opening in a masonry wall needs something to carry the wall above it, whether a lintel, a beam or a brick arch. Standard lintels are made for common spans and loads. An engineer can confirm yours suits what bears on it, and specify something stronger where it doesn’t.

Will replacing a lintel stop the cracks coming back?

If the lintel was the cause, replacing it usually deals with the problem, but cracks that came from other movement can reappear. That is why diagnosis comes first. Your engineer may suggest monitoring the cracks for a while before deciding on repair, and cosmetic repairs should wait until the movement has stopped.

Available across the UK

Professionals cover the whole of the UK: England, Scotland, Wales and Northern Ireland. Planning and Building Regulations differ between the four nations, and your professional will work to the rules that apply where your property is.