Lintel Failure Signs: When to Repair or Replace a Cracked Lintel

Lintels are key structural elements in the construction of any building and are used over doors, window openings and service exits and entryways. When a lintel fails, for whatever reason, the results can be catastrophic.

Being able to spot the early signs that a lintel is failing and may require replacement can stop a problem from becoming a crisis.

Here’s our guide to recognising when a lintel is in trouble, and what to do about it.

Lintel Failure: Early Warning Signs

Your house doesn’t have a dashboard with lights that come on telling you to top up the insulation or any other home maintenance issue, so how do you know when there might be a problem?

Sticky Doors

One of the first early warning signs that a portal lintel (a window or door lintel) may be failing is when a door or a window becomes difficult to use. Problems around window lintels are often first noticed through sticking frames or cracking around the opening.

• Compression of a door or window from additional loads can distort the frame and make it harder to open and close.
•  If the door or window has been adjusted, and the problem has returned, it is likely that it is the lintel and not the fitting that is at fault.
• Has the glass cracked in a window for no clear reason? Pressure from an overhead load can cause glass to crack or chip, or double-glazed sealed units to fail.

Cracking Joints

Another early warning is cracking at brick joints at the corners of the opening where the mortar has come away from the edge of the brick.

• A small crack, at most the length of a brick, could be general movement, settlement, or it could be the start of a bigger problem.
•  If there is cracking at both ends, and the cracks travel in a diagonal direction away from the corner, it is likely that the lintel is on its way out.

Gaps and Bows

A bowing, or distorted wall is a sure sign that all is not well. Displacement and brick misalignment will end up allowing moisture to penetrate a masonry wall and add to the loading over the lintel.

•  A lintel that is having problems may have bricks pushed out of alignment due to excessive pressure.
• There may be a gap visible between the bottom of a steel lintel and the first brick course above it.

Rusty Render

Rust stains on a render or a brick reveal may point to a serious corrosion issue.

•  Steel lintels are usually galvanised these days for enhanced protection, however, dents and scratches during handling or installation can make them vulnerable.
•  If a reinforced concrete lintel is failing and the steel rebar has become exposed to water ingress, rust staining will be an early indicator that all is not well.

These early warnings should not be ignored. Easing a door and repointing a crack may keep the issue at bay for a little while, but if the cracks return, and the door sticks again, it may be time to take action.

Why Do Lintels Fail?

There are several reasons why a lintel may fail. Here is a selection of the main reasons why.

Everything has a working lifetime, and while most lintels made today will most likely outlast us, circumstances may mean that they don’t last as long as they should.

Poor Installation

If a lintel has not been installed properly in the first place, then its lifespan will be foreshortened. A lintel that is not level, doesn’t have the required bearing or has been damaged while being put in position, will not last.

A lintel does not work alone these days either. Most modern cavity wall lintels will require a cavity tray installed correctly to protect them from moisture, and weep vents also need to be installed to take that water away to the outside of the wall.

Water and Steel

Steel lintels that are exposed to a sustained attack from a marine environment may not do as well as the same product inland.

Buildings constructed in the mid to late 20th Century may have been built with ungalvanised, painted lintels. Over the decades, moisture ingress can rust a steel lintel making it expand and force brickwork to separate.

The tell-tale will be a long, linear crack along a mortar joint, allowing more moisture into the cavity and speeding up the problem.

Water and Concrete

Concrete lintels are run through with reinforcing bars, which gives a concrete lintel its tensile strength. If these bars are exposed to damp, the steel will begin to rust and expand, which will lead to spalling and crumbling of the concrete.

Cracks and splits may be visible in the concrete lintel, which will eventually fail if the problem isn’t dealt with swiftly.

A Change in Duty

A building that has been refurbished, extended, or added to with a loft conversion may impose heavier loads upon existing lintels that were never designed for the additional forces.

In some late 20th Century housing developments, structural elements were also heavily value-engineered to reduce costs while still meeting the required standards of the time. This can leave little margin for additional loading decades later.

It may be necessary for a structural engineer to design alternative load paths or specify upgraded lintels where the building use has changed significantly.

UPVC Double Glazing

Many older properties relied upon their original timber window frames to provide additional structural support alongside the lintel itself.

When these windows are replaced with unreinforced uPVC frames, that support can sometimes be lost without the issue being recognised at the time. Over the years this may lead to movement, cracking and eventual lintel failure around the opening.

Where structural support from the original frame is suspected, it may be necessary to specify a replacement lintel or use reinforced window systems designed to carry additional loads.

Ground Movement

Sometimes the failure might not be above eye level at all, but simply be a symptom that all is not well underfoot. Any change to the water table, or ground conditions following local development, flooding events or subsidence can be evidenced in changes in a building’s walls.

Structural integrity can be affected by changes to the foundation that may present as cracking at lintel level, areas where loads meet and are transferred. Subsidence can impose greater loads on a lintel than it was designed to carry, leading to cracking and displacement of bricks and blockwork.

In these cases, there will be other signs such as vertical cracking, and perhaps cracks appearing through bricks. Contact a surveyor to assess the extent of the trouble, and to suggest possible remedies.

The Invisible Lintel Problem

Some older buildings relied entirely upon steel window or door frames for structural support above the opening, rather than using a separate visible lintel.

When these frames are removed during refurbishment or window replacement works, it can sometimes reveal that little or no additional support exists above.

Unless the replacement is genuinely like-for-like, new lintels may need to be installed before the old frames can safely come out. In most situations temporary propping will also be required.

When Is a Failed Lintel Dangerous?

Not every crack above a window or doorway means that a building is about to fall down, however, some warning signs should never be ignored.

A small amount of movement can occur naturally over time as buildings settle and materials expand and contract through the seasons. The concern begins when cracks continue to widen, brickwork starts to bow outward, or windows and doors become increasingly distorted.

If a section of wall appears to be dropping, or there are visible gaps forming around the lintel itself, then the structural load may no longer be transferring correctly to the supporting masonry.

One of the more serious warning signs is when diagonal cracking continues travelling away from the corners of an opening, especially if the cracks appear on both the internal and external wall faces. This can indicate that the lintel is no longer adequately supporting the weight above.

Bulging brickwork, loose masonry and severe rust staining should also be treated with caution. Corroding steel expands as it rusts, and this movement can force surrounding brickwork apart over time.

If there is any doubt regarding structural movement, particularly following a loft conversion, extension, flooding event or signs of subsidence, then a structural engineer or experienced surveyor should inspect the building before further deterioration occurs.

Should I Repair or Replace a Failed Lintel?

Whether or not a lintel requires replacement is dependent upon the level of damage and sensitivity of the building. There are repair options to consider that are less extensive than a complete rebuild, but it can often be worth calling for an expert opinion if you have any doubts.

In all cases the load above the lintel will require stabilisation before any extensive remedial work takes place.

Any lintel repair is also only as good as the associated remedial works that should be addressed, such as moisture protection and proper weep venting.

How Much Does Lintel Repair or Replacement Cost?

The cost of repairing or replacing a lintel can vary considerably depending upon the extent of the damage, the type of wall construction and how accessible the opening is.

Minor remedial repairs using stainless-steel reinforcement bars may be relatively straightforward where movement has been limited and the surrounding masonry remains stable. Once extensive cracking, corrosion or displacement has occurred, replacement is often the more sensible long-term option.

The majority of the expense is often found in the labour and access requirements rather than the lintel itself. Brickwork may need to be removed carefully above the opening, temporary supports installed and scaffolding erected before the failed lintel can safely come out.

Modern cavity wall construction can also make replacement more involved than many people expect, particularly if cavity trays, insulation and damp protection measures require reinstatement afterwards.

Where the failure has been caused by excess loading, such as following an extension or loft conversion, a larger or higher duty lintel may also need to be specified during the replacement process.

In older properties there can occasionally be further hidden complications once work begins, especially where previous alterations have removed structural support that was never intended to be disturbed in the first place.

Can a Cracked Lintel Be Repaired Without Replacement?

In some situations, yes. A cracked lintel does not always mean that the entire structure requires replacement.

If the movement has been minor, and the lintel still retains most of its structural capacity, then remedial repair systems may be used to strengthen the surrounding masonry and stabilise the opening.

Small areas of concrete spalling can often be repaired, and localised cracking above doors and windows may sometimes be reinforced using stainless-steel bar systems bedded into the mortar joints.

The difficulty is that repairing the visible crack doesn’t necessarily deal with what caused the movement in the first place. Moisture ingress, corrosion or additional structural loading may still continue behind the scenes if the wider issue is not addressed.

There does come a point where carrying out repairs stops becoming practical. Severely rusted steel lintels, badly displaced masonry or significant structural movement will often require the existing lintel to be removed entirely.

Where there is uncertainty, particularly in older buildings or where structural alterations have taken place previously, it is generally advisable to seek professional guidance before carrying out remedial works.

Lintel Repair

When you need to repair a brick lintel there is a stainless-steel bar remedial lintel repair system that can be used to reinforce the structure. The mortar pointing to the linear joints is removed to a prescribed depth and the bars are then inserted right across the length of the lintel.

Most systems use two stainless-steel bars grouted in together within the mortar bed to form a new, high-tensile concrete beam that runs within the mortar bed, supplementing the existing support structure.

The mortar joints are then repointed to hide the new steel inserts. This is a good method to use if the movement has been slight, and if it is used alongside other preventive methods that disperse damp or address the root cause of the issue.

Steel Lintel Repair

Steel lintels can remain in place if their supporting capacity is augmented by either steel bars as above, or it may be expedient to simply replace the entire thing, especially if it is well rusted. Steel lintels can be recycled regardless of the condition that they are in when removed from service, however, rust thins steel and reduces its load-carrying capability.

If the lintel comes out of the wall in good condition, and the brick and blockwork are simply displaced, it is likely that the lintel is not the correct duty and will have to be upgraded.

The work required to remove an old lintel is quite extensive. The load above the lintel will require propping (by using acrow props or similar), and there will likely be a need for an access scaffold to reach all areas. When circumstances require that you go to these lengths, then it's worth making sure you don’t ever have to do the job again!

Concrete Lintel Repair

Concrete lintels that are spalling or cracking can be made good if the damage is not too extensive. Using a fast-curing concrete material can be messy, but it is an effective method of repair.

Remove any loose concrete material and take a grinder to the exposed, rusty, steel rebar rods. Once the lintel is back to sound material you can remake the missing parts of the lintel with a rapid-set concrete mix.

Timber and Stone Lintel Repair

Timber and stone lintels sometimes feature in older buildings and can often require specialist repair. Timber can be repaired by inserting steel rods into grooves cut in somewhere out of sight and fixed into position with resin.

A broken stone lintel can be removed and repaired in a similar way. Steel rods should be inserted into chases in the back of the stone and the entire lintel should be bonded together with a proprietary agent.

Next Steps

If you require a new lintel, or the business to repair an existing lintel, at Wade we have the products and expertise to help you sort it out. Get in touch with our team today for helpful, friendly, professional advice.