Lintel Failure Signs: Repair or Replacement Guide

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 lintel may be failing is when a door or a window becomes difficult to use.

• 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 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 or extension may impose heavier loads upon existing lintels not rated for the additional forces.

Additional imposed and live loads must be taken into account when planning a loft conversion. It may be that a structural engineer will be able to detail steel beams so that the load path avoids windows and doorways.

Value Engineering

In late 20th Century and early this century construction, a lot of the specification will have been ‘value-engineered’, or in plain English, designed to maximise cost savings and performance. 

It also means that the lintels are likely not up to the job of supporting a roof and living space at the same time following a loft conversion.

A structural engineer should be able to advise the best way forward in this case.

UPVC Double Glazing

In the 1980s came the rise of the double-glazing salesperson and all across the country old wooden windows were traded out for the new uPVC, energy-saving, sound-deadening modern alternative.

Many homes were improved with lower heating costs, lighter maintenance bills and better security. However, it was common for houses built before the 1930s to rely on their window frames as well as lintels for support.

Most of the time this issue isn’t taken into consideration when the old sturdy timber frames are swapped out and replaced with unreinforced uPVC. Eventually, this will lead to a lintel failure, and they will require replacement.

If window frames are required for support alongside lintels then it is probably a less expensive option to specify steel-framed uPVC or identical timber replacement windows.

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

The mid-twentieth Century was a fantastic time for innovation in construction, and like those older buildings that relied on window and door frames for support alongside lintels, this support was sometimes taken on exclusively by steel doors and windows.

When these doors and windows require an upgrade it is likely that you will find they were made with larger or elongated headers on the frames. There will be little to let you know what’s happening until you start removing them.

Unless you are swapping out like-for-like, its likely that new lintels will need to be specified above the new windows and doors. In both situations, propping will be required.

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.

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.

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