Building safety · Façade defects

Façade defects library. Causes, risks and repair.

The façade and cladding defects we find most often on residential and commercial buildings: how to recognise them, why they matter and how they are put right.

18 defectsReal MTC investigationsUpdated November 2026

Most façade problems show themselves in small ways first: a stain below a window, a panel that rattles in the wind, a fire risk assessment that cannot confirm what is behind the cladding. Every page here is based on our own site work. Examples are anonymised, and no client or building is identified.

Fire risk in external walls

Defects that affect how a wall behaves in a fire, and that a FRAEW to PAS 9980 looks for.

Missing or defective cavity barriersFire-stopping behind cladding that is missing, broken or fitted wrongly.Combustible insulation behind claddingFoam boards where mineral wool was expected.ACM and HPL cladding panelsHow to recognise them and what happens next.Combustible balconies and attachmentsTimber decking, screens and stacked balconies.Over-cladding hiding the original wallNew cladding over an older façade, with no records.As-built walls that differ from the drawingsWhen what was built is not what was designed.

Water ingress

Leaks that damage interiors, structure and insulation, and that are often blamed on the wrong part of the façade.

Curtain walling leaksGlazed façades that let water in, and why resealing often fails.Water ingress at windows and wall junctionsCavity trays, membranes and seals.Failed sealant jointsCracked, hardened or missing mastic.Roof and parapet leaksMembranes, slates, upstands and outlets.

Cladding, render and fixings

Defects that can let panels or render come away from the building.

Loose or damaged rainscreen panelsFixings, impact damage and movement.Corroded brackets and fixingsRust behind the panels, and why it matters.Render cracking and debondingCracks, hollow areas and bulging.Timber cladding and screen decayRot, splitting and loose boards.

Masonry, stone and glass

Age-related and material defects in traditional and glazed façades.

Stone and cast-stone decayCracking, spalling and erosion, and when it becomes a safety risk.Brickwork cracking and wall tie corrosionStepped cracks, bulging and failed ties.Glass breakage and toughened glassSpontaneous breakage and nickel sulphide.Thermal bridging and missing insulationCold spots found by thermography.

Not sure what the problem is?

Many façades have more than one defect, and the visible symptom is often some distance from the cause. A façade defect investigation traces the problem to its source, and a façade condition survey records the condition of the whole envelope.

Our in-house contracting team provides the access and opening-up, so you have one point of contact. Send us the address, what you have seen and any photos, and we typically respond within one working day.

Talk to us

Seen something on your façade?

We investigate façade and cladding defects across the UK, with our own access and opening-up team.

0800 048 5229 enquiries@mtconsult.co.uk See our case studies