Our cement coated EPS (expanded polystyrene) from our team here at Patterson Whittaker Architectural Profiles is quickly becoming a widely used product in architectural design, not only for commercial properties but for residential ones as well.
It’s combination of lightweight foam with durable cement coating means that it’s a product that is easier to install, easier to design, resistant to most elements, AND durable. It is often an architect’s favorite product to work with.
Still, like any exterior surface, cement coated EPS can be damaged due to impact, weathering, or improper handling during construction.
Fortunately, in most cases, repairs can be made without full replacement of the component. The process requires attention to detail and correct material matching to ensure that the repaired section maintains both its appearance and its performance characteristics.
Step-by-Step Repair Process
Repairing damage to cement coated architectural EPS requires more than just cosmetic patching. The process must ensure that the structural integrity of the component is restored and that water cannot penetrate through the surface. The following steps are generally recommended:
Assess the Extent of the Damage
Examine whether the damage is superficial (limited to the cement coating) or structural (penetrating through to the EPS core). If water intrusion has occurred, confirm that the underlying foam is dry and free of mold or deterioration.
Remove Loose or Damaged Material
Use a utility knife or margin trowel to remove any loose or crumbling cement coating. For deeper punctures, carefully cut away the damaged foam and square the edges to allow for a proper patch.
Replace EPS Material if Necessary
For structural voids, cut a replacement EPS insert that fits snugly into the removed section. Use compatible adhesive to secure the foam in place. Avoid gaps between the original and replacement foam that could weaken the repair or allow moisture ingress.
Reapply Cementitious Coating
Once the EPS is repaired, recoat the surface using the same type of polymer-modified base coat originally used during manufacturing. Apply it in thin, even layers using a trowel, feathering the edges to blend with the surrounding surface. In some cases, embedded fiberglass mesh may be required for additional reinforcement.
Allow Proper Curing Time
Cement coatings require a full cure to harden effectively. Avoid painting or sealing the area until the manufacturer-recommended cure time has passed. Curing conditions—such as temperature and humidity—can affect the final strength and durability of the patch.
Touch Up Finish or Paint if Applicable
If the surface was painted or textured, use compatible products to restore visual consistency. Ensure color matching and test small areas before applying to the entire repair site.
Best Practices for Long-Term Durability
While EPS products are designed to be resilient, proper repair technique can determine how long the component continues to perform effectively. Keep the following considerations in mind:
- Only use materials that are compatible with the original cement coating and EPS formulation.
- Avoid sealing the surface too early, which can trap moisture and weaken the repair.
- Inspect repaired areas seasonally for new signs of cracking or detachment.
- Use high-quality paint or coatings with UV protection if the surface is exposed to direct sunlight.
For widespread damage or repeated failures in the same area, it may be appropriate to evaluate whether installation conditions or drainage issues are contributing to premature wear.
Targeted Repairs Preserve Architectural Integrity
Cement coated architectural EPS is engineered to be a long-lasting and visually impactful exterior solution. When damage occurs, targeted repairs using correct materials and techniques can restore both function and appearance without the need for full replacement. Proper assessment, material compatibility, and surface preparation are critical to maintaining the integrity of the system over time.
