Preventing Composites from Warping

Wood has long been susceptible to warping due to its natural tendency to absorb moisture and expand with temperature changes. Traditional wood siding, decking, and trim can warp overtime leading to costly repairs and ongoing maintenance headaches.

Composite building materials offer a superior solution to wood’s inherent warping problems. Made from engineered materials that resist moisture absorption and thermal movement, composites can provide your project with enhanced dimensional stability. However, like all building materials, composites require proper installation and finishing to maximize their performance and prevent warping. In the blog below, we’ll cover the steps to take to prevent your composite materials from warping.

Why Do Composites Warp?

Wood’s cellular structure naturally absorbs and releases moisture, causing it to expand and contract significantly. This movement, combined with wood’s grain patterns and natural defects, makes warping almost inevitable over time. Even pressure-treated lumber can twist and bow as it dries and ages.

Composites are engineered to minimize these issues. By combining plastic resins with stable fillers, composite materials resist moisture absorption and maintain more consistent dimensions across temperature fluctuations. Like nearly all building materials, some composites can also warp under extreme temperature or if not properly installed or coated. These issues are largely preventable and with the right preparation and installation. 

Choosing Stable Composite Materials

Not all composites are created equal. Materials that blend organic fillers like wood flour with plastic are more likely to absorb water or fluctuate in heat. Newer-generation materials—especially those made from non-absorbent, sustainable fillers—offer much greater dimensional stability.

ACRE by Modern Mill, a composite made from upcycled rice hulls, is a great example. Rice hulls are naturally moisture-resistant and is a natural protector to rice grains. As a result, ACRE maintains its shape and appearance better than traditional wood composites, even in challenging climates.

Ensuring Optimal Composite Performance

While composites outperform wood in dimensional stability, proper installation and finishing are essential for preventing any warping:

Installation Best Practices

• Follow manufacturer guidelines – Each composite product has specific fastener spacing and gap requirements. Visit Modern Mill’s Tech and Training page for full guidelines when working with ACRE.
• Leave expansion gaps – Allow for natural thermal movement at board ends and joints
• Use proper fasteners – Choose manufacturer-recommended screws and avoid over-tightening
• Approved paints & stains – Use manufacturer approved finishes, for composites this often means water based finishes with a specific light reflective value (LRV) to combat heat build up

Why Builders Prefer ACRE for Dimensional Stability

ACRE’s resistance to warping stems from its innovative makeup. Unlike wood composites that can wick moisture, ACRE is naturally moisture-resistant and maintains its shape better. Rice hulls don’t absorb water like wood fibers, resulting in exceptional resistance to swelling, shrinking, and warping.

This innovative composition, combined with proper installation techniques, makes ACRE ideal for applications where long-term dimensional stability is critical—from sustainable trim, siding, decking and other applications.

Conclusion

Wood’s susceptibility to warping makes it a challenging choice for many building applications. Composite materials provide a reliable alternative that resists warping while delivering the aesthetic appeal of natural wood. When properly installed and finished according to manufacturer specifications, composites like ACRE offer decades of stable performance with minimal maintenance.Ready to build smarter with stable composite materials? Order samples or contact our team below to explore how ACRE can elevate your next project.