The critical role of protective coatings in modular construction

Published 18 September 2024

Modular construction continues to gain traction as the construction industry continues to recover post-COVID. Building prefabricated components offsite and transporting them to the construction site for assembly has several advantages, including faster construction times, lower costs, predictability and increased sustainability, according to Fortune Business Insights.

The research firm projects the North American modular construction market to grow from $21 billion in 2023 to $34 billion by 2030 across various sectors, including residential, commercial and industrial construction. However, this construction approach brings new challenges, particularly in protecting steel components during transport and installation. Coatings have emerged as a critical solution, ensuring durability and safety from fabrication to onsite assembly.

Innovative Coatings 101

Modular construction requires protected steel components that can withstand the rigors of transportation from the fabrication shop to the construction site—sometimes from one continent to another—and stresses resulting from environmental exposures and steel-erection practices. High-performance coatings offer flexibility and toughness for greater protection against the demanding conditions imposed on steel components during modular construction.

Durable coating solutions bond to the substrate, designed to be applied before arriving at the construction site, providing a protective layer that can accommodate the coefficient of thermal expansion and compressive, flexural or tensile strain without compromise. This prevents stress cracking, brittle fracture and delamination, all common issues in transporting long-span beams or assembled truss components for large-scale projects such as semiconductor or electric-vehicle battery facilities. This adaptability reduces the need for unquantifiable onsite repairs that can drive up costs and contribute to project slippages.

Safety First

One key advantage of modular construction remains safety, and specialized coatings significantly complement this aspect. An innovative intumescent epoxy coating, for instance, provides ductile and robust cellulosic fire protection for up to four hours, helping to ensure the structural integrity of steel in the event of a fire.

Upon exposure to high temperatures, the coating expands from a thin layer to a thick insulating barrier, preserving the steel's stability. For a finite period, coated steelwork inherently resists fire, offering a strong line of defense in case of a fire during construction. This preemptive measure helps ensure that the structure can withstand the fire event, rather than undergoing a total loss, and be restored relatively easily. Its design helps steel structures remain intact in high-temperature situations and provides substantial corrosion resistance, fulfilling the International Organization of Standardization 12944 C5 standard without needing an extra topcoat.

Economic Benefits

Applying steel coatings in the fabrication shop provides a degree of predictability, contributing to efficiency improvements that add value and lower project costs and timelines. Steel components that arrive onsite already coated eliminate unnecessary downtime, integrating smoothly into the construction schedule by reducing the volatility around trade stacking and environmental constraints for optimum application and curing. These coatings, which can be applied using sprays, are ideal for use in both modular yards and onsite.

This approach also reduces labor and material costs by decreasing the need for extensive repairs and downtime. Durable coatings result in fewer replacements and repairs after being transported from the fabrication shop to the construction site. The coatings can be painted within a day and are ready to be moved to the site the following day. Their easy application boosts efficiency, whether in modular yards or onsite.

Sustainability benefits

Amid a growing commitment to a reduced environmental footprint, the construction industry turns to modular construction and coatings for more sustainably advantaged solutions. For example, shipping precoated steelwork can cut down on logistical expenses and environmental impacts. Unlike the onsite application of bulky, lightweight sprayed fire-resistant material that demands several inches depending on fire-resistance ratings, in addition to large volumes of disposable, single-use polyethylene rolls used to protect adjacent areas, the slender yet robust layer of protective coatings—measuring 1-3 millimeters—allows for more steel per transport, reducing costs and potentially carbon-dioxide equivalent emissions.

Case study

A leading German biotechnology company known for developing active immunotherapies partnered with one of Portugal's largest steel constructors to address the need for robust fire protection at their new manufacturing facility in Kigali, Rwanda. The project faced significant logistical and environmental challenges, requiring a fire-protection solution that could endure a 90-minute standard fire scenario and withstand transportation from Portugal to Rwanda.

The team applied a cellulosic passive fire protection coating, recognized by ISO standards and known for flexibility and high performance in C3 and C5 corrosivity environments. The application of this coating was vital for meeting the project's demanding needs, allowing for efficient application and damage-free transportation. Not only was the project completed on schedule in four months with 60,000 kg of the coating efficiently applied, but the durability of the coating also ensured that the structures could be transported without damage, arriving in Rwanda ready for quick construction and assembly. This case serves as a prime example of how coatings can enhance the integrity and safety of large steel structures.

Specialized coatings offer greater protection and efficiency for modular construction. By investing in these protective technologies, construction executives have a greater opportunity to deliver successful projects on budget and ahead of schedule.

By Stuart Bradbury
Stuart Bradbury is the business development manager of fire protection, protective and marine coatings at PPG. He has more than 20 years of experience dedicated to the design, management, testing and implementation of mitigation measures for fire, explosion, and cryogenic spill hazards.