Failing pitched metal roofs and the case for cold-applied solutions

Across the UK, the scale of the problem is immense. Tens of thousands of metal-clad buildings erected during the post-war expansion and late 20th century now show signs of wear, leaks, corrosion and thermal inefficiency. Full roof replacement is often costly and disruptive, prompting a growing movement toward refurbishment using modern cold-applied waterproof solutions. 

Corrosion is one of the most common threats to metal roofs, particularly in the UK where high humidity, frequent rainfall and coastal environments contribute significantly. When metal surfaces are exposed to moisture and pollutants over time, especially salt in coastal areas, it accelerates oxidation. 

Corrosion often starts in cut edges or fastener points, overlapping seams and damaged protective coatings or poorly maintained finishes. If left untreated, corrosion can eat through the panels, leading to leaks, weakened load-bearing capacity and potentially the need for a panel or full roof replacement.

Another major issue is leaks from failed seals at panel joints, damaged or shrinking gaskets around fasteners or cracks in the flashing - and around detailed areas such as vents or skylights. Even the smallest leaks can lead to interior issues, such as damp insulation reducing thermal efficiency, mould and mildew growth – and most alarming - electrical hazards or damage to stock in industrial units.

Metal roofs are highly reactive to temperature changes. As they expand and contract fixings can become loose, panels can warp or develop stress fractures and seams can separate over time. This is particularly problematic on older roofs with fewer expansion joints or less flexible fixing systems. 

We also have to consider the overall look of the building. Apart from structural issues, visual deterioration can impact a building's value and its tenant appeal. Common forms include UV fading of paint or coatings, staining from water runoff or pollutants, moss, lichen and algae growth in shaded or wet areas.

When prompt action is needed

All of these factors demand prompt action. Delaying repairs or refurbishment of pitched metal roofs can lead to accelerated deterioration and higher costs in the long term from repeated emergency repairs, or even full replacement and potential business interruption if leaks cause damage and disruption to operations.

A proactive approach - especially using a cold-applied system such as Pro-Cold® from Proteus Waterproofing® - that is non-disruptive, can restore performance, protect the structure and extend the roof sheets life.

Refurbishment can cost 30–60% less than full replacement. Refurbishment, in the case of Pro-Cold®, involves applying a protective, waterproofing overlay system rather than removing and disposing of existing panels. Without the need to strip out old materials, labour costs are reduced. This makes refurbishment particularly attractive for large-scale industrial buildings where roofing areas frequently span thousands of square metres.

Another of the most overlooked advantages of refurbishment is how it minimises disruption to ongoing business activities, when opting to use cold-applied solutions. There is rarely the need to stop work inside the building, there is a reduced health and safety risk with no hot works. Phased work plans can allow for “business as usual.” This is vital for logistics hubs, warehouses, manufacturing plants and retail spaces where downtime can be costly or impractical.

Avoiding the removal and disposal of existing roof materials also prevents waste from reaching landfills. Furthermore, there is less embodied energy used in manufacturing, transporting and installing new materials. Refurbishment extends the lifespan of an existing asset, aligning with circular economy principles.

Enhanced roof performance

Refurbishment is not just about patching up the past.  Modern systems such as Pro-Cold®, when used in refurbishment can provide insulation upgrades to reduce heat and cooling costs. Also deliver seamless water protection even on difficult pitched geometries with BBA certification and a potential additional lifespan of up to 20 years.

Refurbishment is often the best option when the metal panels are structurally sound, but showing signs of surface wear, leaks and corrosion or when there are minor-to-moderate performance issues without widespread structural damage. The same applies if there is a need to keep costs down or to avoid operational downtime.

In many cases, roof refurbishment is not just a cost-saving measure, it’s a strategic investment in the building’s future. By restoring protection and improving performance without the burden of full-scale roof replacement works, refurbishment may provides both financially and environmentally savings.

Cold-applied roofing systems such as Pro-Cold® from Proteus Waterproofing®, have emerged as a preferred method for refurbishing pitched metal roofs. These systems offer several benefits, such as eliminating the need for open flames or hot equipment, which reduces fire risks during installation. Cold-applied systems can adhere to a variety of substrates making them suitable for a range of roofing applications. They also create a continuous, waterproof membrane that effectively seals joints and other penetrations. Once cured, such systems offer resistance to UV radiation, temperature extremes and environmental pollutants.

Refurbishing pitched metal roofs using cold-applied systems like Pro-Cold®, presents a compelling solution for extending the life of industrial and commercial buildings in the UK. This approach effectively addresses common roofing issues, offers cost and environmental benefits and aligns with the evolving needs of modern businesses. By choosing refurbishment over replacement, building owners can ensure the life their properties roofs while contributing to a more sustainable built environment.