By Sandra Sint, senior associate at built environment consultancy Hollis.

Many of the curtain wall-style office building façades that have shaped the UK’s commercial landscape since the 1980s are approaching, or have exceeded, their original design life. This is typically considered to be between 25 and 40 years.

As a façade consultant working across commercial portfolios, I’m increasingly asked the same question: how should ageing glazing systems be managed before they develop into more complex problems?

In some cases, limited investigation or assumptions based primarily on age can result in façades being prematurely categorised as requiring full replacement, causing significant implications for cost, operational disruption and asset value. Understanding the true condition of the façade is therefore critical to making informed decisions.

The gradual deterioration of curtain wall systems

Although many façades continue to perform reasonably well beyond their intended service life, the components that keep the systems weathertight and structurally reliable naturally degrade.

Insulated glass units rely on edge seals (the perimeter seals that maintain the airtight cavity), which may fail over time. Sealants exposed to decades of UV radiation, heat and pollution can shrink or crack. Gaskets harden and lose the elasticity needed to maintain airtightness and prevent water ingress.

These are typical age-related behaviours rather than unexpected defects, so while they’re not necessarily significant in isolation, their cumulative presence can indicate that the façade is entering the later stages of its service life and warrants further investigation.

Early warning signs

The first indicators of deterioration often appear inside the building.

For example, tenants may report cold spots, inconsistent temperatures, fogging of the glazing or draughts, while facilities teams may notice unexplained spikes in energy use or recurring incidents of water ingress.

These clues usually suggest that the façade is no longer performing as originally intended and that further assessment is needed.

What a structured façade assessment involves

Typically, a façade assessment begins with a review of available information – including original design documentation, previous inspection reports and maintenance records – to understand how the façade was constructed and maintained throughout its life.

Façade engineers then carry out a visual inspection to identify any issues and signs of deterioration.

In some cases, intrusive investigations may be required to examine concealed elements, such as drainage channels and other critical façade components. This helps determine whether defects are isolated issues or part of a wider pattern of ageing across the façade.

Consider the most appropriate intervention

The right response depends on the extent of the deterioration and the building’s wider strategy.

Sometimes, localised repairs – like replacing failed glazing units or renewing specific sealant joints – can extend the life of the façade at relatively low cost.

In many cases, targeted refurbishment can provide a practical alternative to wholesale replacement, extending service life while reducing cost, disruption and embodied carbon.

Well-planned refurbishment strategies can often significantly improve façade performance and delay the need for more extensive interventions.

Many owners are now choosing to upgrade façades to meet higher energy performance expectations and align with broader ESG goals. In such cases, full façade replacement may represent the most effective long-term solution.

Repair and refurbishment interventions can often be delivered on a phased basis, so buildings can remain operational.

Ageing façades and the wider asset strategy

Façade condition is closely linked to building performance, energy efficiency, occupier comfort and overall asset value. Managing deterioration early helps prevent unplanned failures and allows owners to plan interventions in a coordinated and cost-effective manner.

A robust, evidence-led assessment can help ensure decisions are proportionate, avoiding both premature capital expenditure on full replacements and the risks associated with underestimating underlying issues.

Looking ahead

As more commercial buildings age, managing their glazing systems will become an increasingly important consideration for owners, asset managers and investors.

The challenge is not simply in identifying deterioration but understanding its significance and selecting the most appropriate response. Through robust, evidence-led assessments and timely intervention, owners can make informed decisions that balance safety, performance, sustainability and long-term investment objectives.