Lintel replacement & repair

Lintel failure has a recognisable signature. The classic signs are:

• Horizontal cracking directly above a window or door , often running along the mortar bed just above the opening.
• Stepped diagonal cracking Rising from the corners of the opening.
• Rust staining Bleeding out of the mortar joint above the opening.
• Brickwork lifting or bulging Above the window, sometimes with the course visibly pushed out of line.
• Visible rusted or flaking steel Where the lintel is exposed at the head of the opening.
• Windows and doors sticking Or going out of square as load transfers onto the frame.

The expansion of rusting steel is powerful enough to lift masonry, which is why this problem gets worse rather than stabilising. It is worth acting on when you first see rust staining, not when the brickwork starts moving.

Water is always the cause. It reaches the lintel through failed or missing flashing over the opening, perished mortar joints in the brickwork above, blocked weep holes that stop the cavity draining, defective sills or window head detailing, or simply a lintel that had inadequate protection or cover from the start.

Replacing a lintel without correcting the water path means the new one will go the same way, so the flashing and drainage are part of the repair, not an optional extra.

Traditional lintel replacement

The brickwork above the opening is temporarily supported, the corroded lintel is removed, a new appropriately protected lintel is installed with correct bearing and flashing, and the brickwork is rebuilt and repointed. This is the right approach where the lintel has failed badly, where the opening needs to be reworked, or where the brickwork above is already substantially damaged.

HeliFix masonry beam repair

As a licensed HeliFix applicator, we can often form a reinforced masonry beam within the brickwork itself. Helical stainless steel bars are bonded into the mortar beds above the opening so the brickwork spans the opening as a beam in its own right, taking the load off the corroded lintel.

Where it is suitable, this approach is significantly less invasive: no dismantling of the brickwork above the window, far less disruption, a shorter programme, and no visible evidence once the joints are repointed. It is particularly valuable on period and heritage brickwork where taking an opening apart risks damaging bricks that cannot be matched.

Which approach is appropriate depends on the extent of the corrosion, the condition of the surrounding masonry and the loads involved. We assess and tell you which one your opening needs.

1. Inspection of the opening, the crack pattern and the water path causing the corrosion.
2. A written scope and quote setting out the recommended repair method and why.
3. Temporary support where required, and correction of flashing, weep holes and drainage.
4. Lintel replacement or HeliFix masonry beam installation.
5. Rebuilding, repointing and making good so the finished opening matches the surrounding wall.

The wider the opening, the more load the lintel carries and the more dramatic the failure. Garage door lintels are the ones we replace most after windows. They are long, they are low to the ground where they get splashed, and the brickwork above them is often a full storey high. Signs are a sag in the brick course above the door, cracking at the corners, rust bleeding from the joint and a door that has started to bind at the top. Repairing a garage lintel involves propping the brickwork above, removing the corroded steel and fitting a new lintel with correct bearing at each end, or forming a HeliFix masonry beam where the brickwork allows it. Either way the door frame and the flashing above it are checked and corrected at the same time.

Not every lintel is a steel angle. Pre-war homes often have a flat arch of bricks on edge over the opening, sometimes supported on a thin steel arch bar that has since rusted. Some mid-century homes have precast concrete lintels that crack or spall when the reinforcement inside corrodes. Heritage openings with segmental or semi-circular brick arches can drop when the abutments spread.

These are exactly the openings where HeliFix masonry beam repair is at its best. Reinforcing the brickwork above the opening with bonded helical bars restores the span without dismantling an arch that could never be rebuilt to match. Where a concrete lintel has spalled, we treat it as a concrete cancer repair: break out, treat the steel, reinstate and protect.

Usually not. With traditional replacement the brickwork above the opening is propped and the lintel is removed and replaced from the outside, with the window frame protected in place. Where the frame has been distorted by the lifting brickwork it may need re-fixing or adjusting afterwards, and occasionally a timber frame that has rotted from the same water needs repair, which we can do in-house alongside our heritage window timber repairs. With a HeliFix masonry beam the window is not disturbed at all.

A new lintel that is left in the same wet conditions as the old one will rust the same way. Every lintel repair we do includes checking and correcting the head flashing above the opening, clearing or forming weep holes so the cavity can drain over the lintel, checking the sill and window head sealant, and repointing any perished joints in the brickwork above. On cavity walls we make sure the flashing is dressed over the lintel and turned up inside the cavity, which is what many original installations skipped.

Lintel repairs are priced on the width of the opening and the load above it, whether it is a traditional replacement or a HeliFix beam, how much brickwork has to be rebuilt or repointed, the access (ground floor or upper floor, and whether a scaffold is needed) and whether the flashing and window frame need work. A single ground-floor window lintel with sound brickwork is a small job; a garage lintel under a storey of cracked brickwork is not.

The inspection and written quote are free, and the quote sets out which repair method we recommend and why. Where an engineer’s design is required for a HeliFix warranty, that is included in the process.

• What are the signs of a failed lintel? A horizontal crack in the mortar directly above a window or door, stepped cracks rising from the corners of the opening, rust stains bleeding out of the joint above it, brickwork lifting or bulging above the opening, and windows or doors that have started to stick or go out of square.
• Why do steel lintels rust? Water reaches them through failed or missing head flashing, perished mortar joints above the opening, blocked weep holes that stop the cavity draining, or poor sill and window head detailing. As the steel rusts it expands and lifts the brickwork above, which is what causes the cracking.
• Can a rusted lintel be repaired without replacing it? Often, yes. As a licensed HeliFix applicator we can bond helical stainless steel bars into the mortar beds above the opening so the brickwork spans the opening as a reinforced beam in its own right, taking the load off the corroded lintel without dismantling the wall. Where corrosion is severe or the brickwork is badly damaged, traditional replacement is the right repair.
• Does the window have to be removed to replace a lintel? Usually not. The brickwork is propped and the lintel is replaced from the outside with the frame protected in place. With a HeliFix masonry beam the window is not disturbed at all.
• How long does lintel replacement take? A single window lintel is typically one to two days on site, including rebuilding and repointing the brickwork. A garage lintel or an opening with extensive brickwork damage takes longer. HeliFix beam repairs are usually quicker than traditional replacement because no brickwork is dismantled.
• Do you repair concrete lintels and brick arches? Yes. Spalled precast concrete lintels are repaired as a concrete cancer repair, and brick arches and flat arches on period homes are reinforced with HeliFix masonry beams so the arch does not have to be taken apart.
• Is the repair visible afterwards? With a HeliFix beam, no: the bars are inside the mortar joints and the joints are repointed with matched mortar. With traditional replacement the rebuilt brickwork is repointed to match and the new lintel is only visible as a clean edge at the head of the opening.

Lintel failure usually appears with other masonry problems. We also carry out HeliFix crack stitching, brick repointing and render crack repairs.

• HeliFix crack stitching
• Leaking balcony repairs
• Render crack repairs
• Concrete crack repairs