Why Some SPC Planks Warp While Others Stay Flat for Years 2025
SPC flooring is known for dimensional stability. The stone plastic composite core resists expansion and contraction better than other flooring types. But some planks can warp or cup after installation. Here is why it happens.
Cooling Process at the Factory
After SPC planks are extruded, they must cool evenly to room temperature before packaging. If planks are stacked too quickly or stacked while still warm, the weight of the stack can cause slight warping. The bottom planks in a stack cool slower than the top planks. This temperature difference creates internal stress that shows up as warping later.
Good factories control the cooling process carefully. They use cooling racks that allow air circulation around each plank. They wait sufficient time before stacking. The cooling time varies by season. Summer cooling takes longer because ambient temperature is higher.
Raw Material Moisture Content
Limestone powder and PVC resin both have moisture content specifications. If raw materials arrive at the factory with higher than specified moisture, the moisture can cause issues during extrusion. The water turns to steam at high temperature and creates micro voids in the core. These voids weaken the structure and can cause uneven expansion later.
Factories that test incoming raw materials for moisture content avoid this problem. Factories that skip incoming inspection may produce planks with hidden weaknesses.
Uneven Core Density
During extrusion, the core material should have consistent density across the entire plank width. If the extrusion parameters are not correctly set, the center of the plank may have different density than the edges. This density difference causes the plank to expand and contract unevenly when temperature changes. Over time, the plank develops a slight curve.
Storage Conditions Before Installation
If SPC planks are stored in a hot warehouse before installation, the planks can develop a temporary curve. This usually flattens after acclimation in the installation room. If planks are stored leaning against a wall instead of flat, they can take a permanent set. Always store SPC planks flat in a climate controlled area.
Subfloor Issues
Even a perfectly flat plank will warp if installed over an uneven subfloor. The plank follows the subfloor shape. If the subfloor has a high spot, the plank bends over it. This is not a product defect but an installation issue.
What to Do If You Receive Warped Planks
If you open a carton and find slightly warped planks, lay them flat in the installation room for 48 hours. Most planks flatten during acclimation. If planks do not flatten after 48 hours, they may have a permanent warp. Set these planks aside and request replacements from the factory. Keep photos and document the issue.
About PROLEADER
PROLEADER controls the cooling process carefully at our factory. We test raw material moisture and maintain consistent extrusion parameters. Our planks are stored flat before packaging. Contact us for quality specifications.
