When Lintels Go Wrong and What Actually Needs Doing About It
Lintels hold up the brickwork above windows and doors. When they fail, you get anything from annoying cracks to walls that are genuinely dangerous. Most people don’t think about lintels until there’s a problem, by which point working out whether it needs urgent attention or just monitoring isn’t straightforward.
Lintel repairs sort out lintels that have corroded, rotted, or were never big enough for the job in the first place.
What Lintel Failure Looks Like
Diagonal cracks running upward from the corners of windows or doors are the giveaway. The crack pattern forms a rough triangle above the opening as the brickwork tries to support itself without a working lintel underneath.
If the masonry directly above a window or door has sagged, the lintel has deflected. Rust stains on external walls near openings mean steel corrosion. The frame itself might have twisted, sticking when opened.
Why They Fail
Steel lintels rust when damp gets to them. This happens a lot where cavity walls don’t have proper damp-proof courses or where wall ties have failed and let moisture through. Steel expands as it corrodes, cracking the surrounding brickwork and eventually losing the strength to hold anything up.
Timber lintels rot when damp gets to them. Victorian and Edwardian houses often have timber lintels that have deteriorated over decades.
Some lintels were just too small from the start. Older buildings often used lintels sized by guesswork rather than calculation. They bend gradually over years until something gives.
Getting It Looked at Properly
Structural engineers assess lintels by looking at them, sometimes opening up the brickwork to see the full extent of what’s going on. How much corrosion or rot there is determines whether repair is possible or whether replacement is the only sensible option.
Repair or Replacement
Minor rust on a steel lintel can sometimes be dealt with by cleaning back to sound metal, treating it against further corrosion, and rebuilding the brickwork around it. This only works if there’s enough solid metal left to do the job.
Heavy corrosion or rotten timber means replacement. The brickwork above gets temporarily propped, the failed lintel comes out, a new one goes in that’s actually up to the job, and the disturbed brickwork gets rebuilt.
What Goes In
Replacement lintels are usually steel, galvanised or powder-coated against rust. For cavity walls, cavity lintels with built-in damp-proof course are standard. Concrete lintels suit situations where fire resistance matters.
Holding Things Up Whilst You Work
Replacing a lintel means temporarily supporting the wall above it. This usually involves needling, pushing steel beams horizontally through the wall above the opening and propping them from either side. This takes the load off whilst the old lintel comes out and the new one goes in.
Getting the temporary support right is critical. Bodging this bit has caused serious collapses.
What It Costs
A straightforward lintel replacement for a standard window opening typically runs £1,500-3,000 including temporary works, the new lintel, and making good afterwards. Bigger openings or awkward access push costs up considerably.
If you’re replacing multiple lintels across a property, you’re looking at £10,000-20,000+ depending on how many there are and how difficult they are to get to. Scaffolding for upper floors adds a fair bit.
Stopping It Happening Again
New cavity walls should have proper damp-proofing over lintels. Cavity trays and weep holes stop water building up and causing corrosion. Regular maintenance, clearing blocked weep holes and fixing failed pointing, keeps moisture out.
For existing buildings, catching lintel problems early means you can intervene before failure is advanced. Sorting out minor cracking early prevents expensive emergency work later.
Professional lintel work operating across the UK covers assessment, engineering design, and installation for buildings where lintels have failed or weren’t adequate to start with.
