Lintel Failure: Identification and Replacement

Lintels carry the wall above window and door openings. When they fail, cracks appear in the brickwork above and below, doors stick, and rain finds its way in. The diagnosis is usually quick; the replacement is invasive but well-rehearsed.

Signs of lintel failure

• Diagonal cracks above the opening, often stepping out from corners
• Sagging brickwork course directly above
• Door or window frame distorting
• Cracks in plaster above the opening internally
• Visible rust staining (steel lintels) or rot (timber lintels)

Common lintel types and failure modes

Stone or concrete lintels (old buildings)

Cracking from overload or inadequate end bearing. Sometimes carbonation and reinforcement corrosion.

Timber lintels (pre-1900)

Rot at ends (where moisture wicks in), beetle infestation, or simple decay.

Mid-century steel angles

Galvanising fails, steel corrodes, expanding rust splits brickwork above. Common in 1950s–1980s houses.

Modern proprietary lintels (Catnic, IG, Birtley)

Generally robust but failures occur from overload (kitchen extension without lintel upgrade), water ingress, or galvanic corrosion.

Replacement process

1. Engineer specifies replacement lintel size and type
2. Temporary props install above and below opening
3. Brickwork above lintel cut out
4. Old lintel removed
5. New lintel inserted, padstones if needed
6. Brickwork rebuilt above
7. Make good internally and externally

Cost

• Single window lintel replacement: R24,000–R56,000
• Front door lintel (with brickwork rebuild): R40,000–R90,000
• Large opening (bay window, French doors): R70,000–R150,000
• Structural calculations: R7,000–R14,000

When you can defer

Hairline cracks above an opening that don't grow over 12 months are usually not urgent. Active cracking, sagging brickwork, or visible distortion warrant action.

MCFAR specifies lintel replacement on residential and commercial buildings.

Frequently Asked Questions