The growing need to refurbish metal box gutters on industrial buildings

Traditionally, refurbishing these gutters has been labour-intensive, often involving hot works such as torch-on membranes or welding, both of which carry a fire risk. With stricter health and safety regulations, and insurers increasingly wary of such on-site fire hazards, it is understandable why cold-applied waterproofing systems are rapidly becoming the preferred systems of choice. 

Box gutters have been a staple of industrial building design for over half a century. Stretching across factories, warehouses and large retail units, these gutters manage the enormous volumes of rainwater that such expansive roofs collect. Based on anecdotal evidence, it’s estimated that the UK has tens of thousands of miles of box guttering on commercial and industrial properties alone, much of which is made from galvanised steel or aluminium. These systems are often concealed between roof slopes, which means there’s a risk they can be easily neglected during routine maintenance, even as corrosion and joint failure begin to compromise their integrity.

As a result, after decades in service, many of these systems are approaching or have surpassed their original design life. Corrosion, thermal movement, joint fatigue, standing water and build-up of debris all take their toll. 
While it is difficult to quantify the exact length of metal box guttering installed across the UK, estimates suggest that there are tens of thousands of industrial buildings using such systems. If we conservatively estimate just 100 linear metres of guttering per building and multiply this by approximately 250,000 industrial units nationwide, the figure quickly rises to over 25,000 km of metal box gutters, an immense network that requires consistent upkeep.

Common problems with ageing box gutters

One of the challenges associated with ageing metal box gutters is corrosion, caused by exposure to water and pollutants, which in turn causes rust and eventual perforation, particularly around joints and fixings. There’s also thermal movement from repeated heating and cooling cycles that leads to expansion and contraction, which can crack joints or distort the metal. Add on the problem of poor design or blockages that frequently result in ponding, and this further increases the amount of stress on the structure and accelerates corrosion. Other problems include leaves, dirt and other materials, which can clog drainage paths and add weight to the system. 
All this means that over time, mechanical joints and mastic seals degrade, leading to drips and potential ingress. When metal box gutters are left to deteriorate, the implications can be far-reaching. Leaks can cause damage to commercial stock, equipment and interior finishes. Persistent moisture can degrade roof structures and load-bearing elements.

Damp interiors can also lead to mould growth, posing health risks to occupants, while ongoing water ingress can lead to expensive claims and increased insurance premiums. In addition, water damage or emergency repairs can result in business downtime and productivity losses.
For many building owners and facility managers, the prospect of full gutter replacement is daunting. It often involves intrusive works, hot processes like welding or torching, and can be prohibitively expensive. Moreover, the associated risks - such as fire hazards, business disruption and long project timelines - make refurbishment an attractive alternative.

Refurbishment using cold-applied liquid waterproofing systems provides a viable long-lasting solution. These systems are designed to fully encapsulate the gutter, sealing all joints, laps and perforations while providing a monolithic watertight barrier. Solutions like Proteus Pro-Cold® provide full waterproofing protection without the need for heat, offering a modern answer to an ageing infrastructure challenge - and doing so in a way that is cost-effective, efficient and compliant with today’s stringent safety standards.

Advantages of cold-applied systems

As already mentioned, traditional methods of refurbishment often involve heat application, which introduces fire hazards - a serious concern on buildings which are housing sensitive operations or high-value stock. Cold-applied systems eliminate this risk, making them safer to install in operational environments.
Cold-applied refurbishment is also significantly more cost-effective than full replacement. Labour and materials are less intensive, scaffolding can often be avoided, and the process can be undertaken without needing to strip out the existing system. Even better -  given that the system is installed without heat or major structural work, operations inside the building can usually continue uninterrupted, preserving productivity and avoiding costly downtime.
Modern cold-applied membranes offer excellent UV stability, flexibility and adhesion to various substrates. Systems like Proteus Pro-Cold® are also BBA certified and can deliver up to 20 years of additional life with minimal maintenance, offering a long-term solution. In addition, cold-applied liquid systems can be used on complex profiles, around outlets and in narrow or restricted areas where other materials might struggle. 

Prevention, of course, is always better than cure. Regular inspections, cleaning and planned maintenance go a long way in extending the life of a box gutter system. Facility managers should schedule annual checks, particularly before and after winter months when freeze-thaw cycles and increased rainfall can exacerbate existing weaknesses. When signs of wear start to appear, such as rust staining, internal leaks or sagging, it is critical to act quickly. Early intervention with a cold-applied waterproofing system can prevent minor issues turning into major problems.
Sadly, the vast network of metal box gutters across the UK's industrial landscape largely goes unnoticed until they fail. But by recognising the importance of these systems and embracing modern cold-applied refurbishment methods, building owners and operators can protect their investments, minimise risk and extend the life of their properties.

Solutions such as Pro-Cold® from Proteus provide a reliable, cost-effective and environmentally friendly way to renew failing box gutters without the upheaval of full replacement. As pressures mount to reduce operational costs, enhance safety and meet environmental targets, such innovations in waterproofing technology will play an ever-growing role in the future of industrial building maintenance.