Written and reviewed by the Apolodor LTD concrete repair team

Precast concrete cladding panels were widely used on UK buildings from the 1960s onwards. They gave designers a fast, flexible way to clad offices, housing blocks, universities, hospitals and civic buildings, and many of those facades are still in service today.

Decades later, many panels are showing their age. Cracking, spalling, staining and failing joints are common, and behind the panel face, the fixings that hold everything in place may also be deteriorating. This guide explains how precast cladding panels should be inspected and repaired. It also sets out how we approach facade projects at Apolodor LTD, where safety and appearance both matter.

Quick answer: Precast concrete cladding panels are repaired by inspecting both the panels and their fixings, removing loose concrete, treating corroded reinforcement, reinstating damaged areas with repair mortars matched to the panel finish, replacing failed joint sealants and applying protective coatings. Corroded or inadequate fixings must be assessed by an engineer and remedied, as they are critical to safety.

Why Do Precast Panels Deteriorate?

• Low cover. Thin panels often have limited concrete over the reinforcement, so carbonation reaches the steel sooner
• Exposed aggregate finishes. Decorative finishes can reduce the effective cover further
• Joint failure. Sealants between panels have a limited life, and once they fail, water reaches fixings and panel edges
• Corroding fixings. Older fixings were not always stainless steel and may corrode where water gets in
• Thermal movement. Daily and seasonal movement stresses panels and fixings

Why Do the Fixings Matter Most?

The most visible defects on a cladding panel are cracks and spalls on the face. The most important ones are often hidden. Fixings connect each panel to the building frame, and if they corrode, loosen or were never installed correctly, a panel can become unstable.

Any inspection of a precast facade should include the fixings, usually by opening up a representative sample, using borescopes or removing joint sealant to look behind panels. Our guide to inspecting concrete for hidden damage explains the general approach.

Step 1: Survey the Facade

A facade survey, carried out from access equipment or by rope access, records:

• Cracking, spalling and delamination on each panel
• Rust staining indicating corroding reinforcement or fixings
• The condition of joint sealants
• Panel movement, displacement or misalignment
• Results of hammer testing, cover measurement and carbonation testing

Loose concrete that could fall is removed during the survey.

Step 2: Assess the Fixings

An engineer reviews the fixing design and condition. Remedial options for deficient fixings include installing supplementary fixings, typically stainless steel, through the panel into the structure behind, or in extreme cases removing and replacing panels.

Step 3: Repair the Panels

Damaged concrete is removed back to sound material, corroded reinforcement is cleaned and treated, and the profile is reinstated. The approach follows the same principles as repairing spalled concrete on external surfaces, with extra attention to appearance because facade repairs are highly visible. Repair mortars can be selected or tinted to suit the original finish, and exposed aggregate effects can be recreated. Where appearance matters, we recommend trial repairs so the finish can be agreed before work continues across the facade.

Step 4: Replace Joint Sealants

Old sealant is cut out, joint faces are cleaned and primed, and new sealant is installed with the correct backing rod and dimensions. Good joint sealing is one of the most effective ways to protect panel edges and fixings from water. Our guide to filling and sealing expansion joints in concrete covers sealant selection.

Step 5: Protect the Facade

An anti-carbonation coating slows further carbonation, reduces water uptake and evens out the appearance of repaired panels. Where the original finish needs to stay visible, clear water-repellent impregnations may be preferred. Our guide to applying anti-carbonation coatings explains the process.

How Are Facade Repairs Planned on Occupied Buildings?

Most cladding repairs take place on occupied buildings. Planning should cover access, protection of windows and entrances, noise and dust, and safety zones beneath the work area. Rope access can reduce cost and disruption on suitable buildings. Our guide to planning a concrete repair project from start to finish sets out the wider process.

How Apolodor LTD Repairs Precast Facades

On a cladding project, we treat the fixings as the priority and the panel faces as the visible part of the job. We make loose concrete safe first, support the engineer’s assessment of the fixings, and then repair panels, replace sealants and protect the facade.

Because these buildings are almost always occupied, we plan access, protection and working hours around residents, staff or students, and keep the client informed as each elevation is completed.

Our Coverage Across England and Wales

We inspect and repair precast facades through our specialist concrete repair services in:

• London
• Manchester
• Birmingham
• Liverpool
• Leeds
• Nottingham
• Bristol
• Brighton
• Cardiff
• Plymouth
• Luton
• Reading
• Norwich
• Swindon
• Portsmouth
• Oxford
• Ipswich
• Maidstone
• Cambridge
• Southampton
• Slough
• Warrington
• Sheffield
• Leicester
• Coventry
• Milton Keynes
• Northampton
• Derby
• Stoke-on-Trent
• Wolverhampton
• Hull
• Exeter
• Gloucester
• Sunderland
• York
• Peterborough
• Chelmsford
• Newcastle
• Bradford
• Bournemouth
• Swansea
• Newport
• Middlesbrough
• Preston
• Blackpool
• Bolton
• Stockport
• Huddersfield
• Lincoln
• Worcester
• Colchester
• Canterbury

Key Takeaways

• Many UK precast facades date from the 1960s onwards and are reaching the age where repairs are needed
• Panel fixings are safety-critical and must be inspected, not just the panel faces
• Repairs should match the panel finish as closely as possible
• Replacing joint sealants is essential to keep water out
• Protective coatings extend the life of repaired facades

Frequently Asked Questions

How do I know if cladding fixings are corroded?

Rust staining at joints, displaced panels and cracking at panel corners can all suggest fixing problems, but opening-up works are usually needed to confirm their condition.

Can damaged precast panels be repaired rather than replaced?

In most cases, yes. Replacement is usually only needed where panels are severely damaged or the fixings cannot be remedied.

How often should panel joints be resealed?

Sealant life varies with the product and exposure, so joints should be inspected regularly and replaced when they show cracking, loss of adhesion or hardening.

Arrange a Facade Inspection

Apolodor LTD inspects and repairs precast concrete facades across the UK. Call 07808 709670 or contact us here.