A crack running up from the corner of a window is one of the most common things homeowners call us about. Sometimes it is cosmetic. Often it is a lintel that has started to fail, and that is worth dealing with before it gets worse.
This guide explains what a lintel does, how to tell if yours is failing, and what replacement typically costs in Sussex.
What does a lintel do?
A lintel is the beam that sits above a window or door opening and carries the weight of the brickwork above it. In older Sussex homes it might be timber, stone or a brick arch. In homes built from the 1960s onwards it is usually concrete or galvanised steel.
When a lintel weakens, the brickwork above it loses support and starts to drop. That movement shows up as cracking.
Warning signs of a failing lintel
- Stepped cracks running diagonally up from the top corners of a window or door
- A sagging or dipping line in the brick courses directly above the opening
- Windows or doors that stick or no longer close properly
- Rust staining or bulging on the face of a steel lintel
- Spalling or cracking across a concrete lintel, often with exposed rusty reinforcement
- Rotten or soft timber where an older wooden lintel is visible
- Internal cracks in the plaster above the window
A hairline crack that has not changed in years is often just settlement. Cracks that are widening, wider than about 3mm, or paired with a sticking window should be looked at promptly.
What causes lintels to fail?
- Steel lintels corroding when water gets in through failed mortar or a missing cavity tray
- Concrete lintels cracking as the steel inside rusts and expands
- Timber lintels rotting after years of damp
- Too small a lintel being fitted originally, or none at all
- Openings widened during past renovations without proper support
What does the job involve?
- The brickwork above the opening is propped with steel props and strongboys so nothing moves.
- The bricks over the old lintel are carefully removed and set aside for reuse where possible.
- The failed lintel is taken out and the bearings at each end are checked and made good.
- A new lintel of the correct size and type is bedded in, with a cavity tray and weep vents where needed.
- The brickwork is rebuilt to match, using reclaimed or matched bricks and mortar.
- Props are removed once the mortar has cured.
Most single window lintels are completed in a day, and in many cases the window itself can stay in place.
Do I need Building Control approval?
Replacing a lintel is classed as structural work, so it generally needs Building Regulations approval. We can advise on the right route for your job, and for larger openings we work to an engineer’s design.
Get the crack checked
If you have cracking above a window or door, we will come and take a look for free. We will tell you whether it is the lintel, settlement or something else, and give you a written estimate with no obligation. Bradford Brickwork is based in Maresfield and covers East and West Sussex and Tunbridge Wells.
Call 07771 393494 or book a free site visit.
