Lintel replacement above windows and doors
A lintel carries the wall above a window or door. When it fails, the signs show up as cracks above the opening, sagging brickwork or windows that stick. Lintel replacement removes the failing beam and installs a correctly sized new one while the wall above is supported. ADB SW carries out structural repairs across South Devon. Send photographs of the cracking inside and out so we can discuss the repair.
Signs a lintel is failing
Common signs include stepped or diagonal cracks rising from the corners of an opening, a visible dip in the brick courses above a window, cracked render or plaster above the frame, and windows or doors that have started to bind. Rust staining or spalling on concrete lintels can indicate corroded reinforcement inside.
Older houses often have timber lintels hidden behind render or plaster. These can rot where moisture gets in, particularly on exposed walls. Some cracks above openings are minor and seasonal, so an inspection should establish whether the lintel has actually failed before replacement is agreed.
Window lintel replacement step by step
Window lintel replacement starts with supporting the masonry above. Temporary props and needles are installed, and the window may be removed or protected depending on the frame. The old lintel is cut out carefully, the bearings at each end are checked, and padstones are added where the masonry needs them.
The new lintel is bedded at the correct bearing length, packed tight to the wall above and the masonry made good. Props are removed only once the mortar has gained enough strength. On cavity walls, a cavity tray and weep holes help manage moisture over the opening, and insulation is maintained to avoid a cold spot.
Choosing the right lintel
Galvanised steel cavity lintels are common in modern cavity walls, while concrete lintels suit many solid walls and inner leaves. On period properties, a replacement may need to match the original appearance outside, using a steel or concrete lintel behind a stone or brick face. Timber may still be appropriate in some traditional buildings where it suits the construction.
The size and type depend on the span, the load above and the wall construction. Larger spans, or openings carrying floor joists or roof loads, may need an engineer’s design. Replacement lintels are usually treated as repairs, but building regulations can apply where an opening is altered or widened.
Making good and arranging the work
Once the lintel is in, the brickwork or render outside is repaired to match as closely as possible, and the plaster and decoration inside are made good. If a window has been removed, it is refitted or replaced and sealed. Where several lintels have failed across one elevation, it can be economical to deal with them together.
For an enquiry, send photographs of the cracking inside and out, the opening width and the wall type if you know it. ADB SW can discuss the repair and provide a written quote. If you want to widen an opening rather than repair it, our structural alterations page explains that work.
Common questions
How do I know if a lintel needs replacing?
Look for diagonal or stepped cracks from the corners of an opening, sagging brick courses above a window, cracked render or plaster, and windows or doors that stick.
How long does lintel replacement take?
A single window lintel is often replaced in a short visit, though mortar needs time to gain strength before props are removed, and making good follows.
Does the window have to come out?
Not always. It depends on the frame and how the lintel is accessed. Sometimes the window is protected in place; sometimes it is removed and refitted.
What affects the cost of lintel replacement?
The span and load, wall type, access, whether the window must be removed, the lintel type and the amount of brickwork, render and plaster to make good.
Tell us about your project
Send the property details and the work you have in mind so the scope can be discussed before a quote is agreed.