A Guide to Restoring Structural Steel at Building Envelopes

Structural steel plays a crucial role in the longevity and functionality of commercial and industrial buildings. Unfortunately, over time, steel deteriorates due to exposure to the elements and other environmental factors. That’s where WCP Building Renewal comes in. In this blog post, we will explore the process of restoring structural steel, from preparation to finish, using a “good, better, best” approach. We will also look at a few coating systems for steel from both Sherwin-Williams and PPG, two trusted names in the industry.

A Guide to Restoring Structural Steel at Building Envelopes

Restoring Structural Steel

Surface Preparation

  • Good: Hand scraping and sanding the surface to remove loose and peeling paint. This method is labour intensive and not recommended in commercial or industrial settings but it is a baseline, it’s a starting point.
  • Better: Removing loose rust and paint using a wire wheel, and / or a grinder. Various blades and tooling can be used to provide different profiles, depending on how deep the rust has penetrated. 
  • Best: For optimal results, sandblasting, vapor blasting or abrasive blasting is recommended to remove all rust, mill scale, and existing coatings. This ensures a sound surface for priming. It is imperative that a “profile” is introduced to the metal for optimal adhesion of any coating system.

Keep in mind as the methods of rust and coatings removal become more aggressive additional steps and costs will be added to the process like site containment or clean up by industrial vacuum. Also, remember appropriate personal protective equipment (PPE) including respirators, gloves, and safety glasses, are necessary when working with metal or using grinders or abrasive blasting.

Cleaning After Prep

  • Regardless of the method you choose, after the preparation is complete, thoroughly clean the steel surface to remove any dust, debris, or contaminants. Power and hand washing is typical but in some instances, commercial cleaners will be required. This step is crucial to remove dust particulates and to ensure for proper adhesion of the primer.


  • Good: Rust-inhibitive red oxide primers. This “old school” rust primer can is manufactured by many coating companies and can be easily sourced.
  • Better: PPG’s PITT-GRIP® Interior/Exterior DTM Industrial Primer is a high-performance primer that offers superior adhesion and corrosion resistance.
  • Best: For the best results, use PPG’s Amerlock 400, a high-performance epoxy primer that provides superior adhesion and corrosion resistance and is regularly used in commercial and industrial settings. This primer is best applied by airless sprayer.

 Finish Coats

  • Good: As a starting point, general-purpose enamel like Sherwin-Williams’ Pro Industrial™ DTM Acrylic. This will provide good aesthetic appeal, durability and protection.
  • Better: Opt for Sherwin-Williams’ Macropoxy® 646 Fast Cure Epoxy for better durability and color retention.
  • Best: PPG’s PSX 805, siloxane topcoat, offers the best long-term protection, color retention, and durability for steel and various metals. This product comes is a variety of sheens. PSX 805 is applied via arieles sprayer and by trained professionals for optimal finish and performance.

Restoring structural steel is crucial to the longevity and functionality of commercial and industrial buildings. Depending on your specific needs and budget, you can choose a “good, better, best” approach to achieve the desired level of protection and aesthetics. 

WCP Building Renewal is here to assist you in every step of the process, ensuring that your structural steel and building envelope are restored to their optimal condition, and ready to withstand the test of time. If you have any questions about your next Building Renewal project we can be reached at [email protected] or 604.420.5552.

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