Composite Siding Problems: What Can Go Wrong?

Composite siding offers many benefits over traditional wood siding. Made from a blend of wood fibers and plastic, composite resists rotting, cracking, and insect damage. It requires very little maintenance compared to natural wood.

However, composite siding is not invincible. There are several potential problems that can occur over time:


Like any exterior building material, composite siding is vulnerable to fading from exposure to sunlight. The plastic portion contains pigments that give the siding color. Over years in the sun, those pigments eventually break down.

Fading is especially noticeable on darker composite siding colors like browns and blues. Lighter shades hold up better. South or west facing walls get more sun exposure and will fade faster.

While fading does not compromise the siding’s performance, it can be an aesthetic concern. Faded siding may need to be cleaned, restored, or replaced to give your home a fresh look.


Chalking is similar to fading but affects the surface texture of composite siding. As plastic ingredients are degraded by UV rays, microscopically fine chalky powder begins to form on the surface. This gives the siding a dull, faded appearance.

Like fading, chalking is mainly a cosmetic issue. It does not directly affect the siding’s durability. But extensive chalking both looks bad and can make the surface harder to clean or repaint.


Unlike wood, composite siding does not absorb water. But it can still warp or bend over time under certain conditions:

  • Improper installation where underlying materials retain moisture
  • Inadequate expansion gaps during installation
  • Extreme temperature shifts causing contraction/expansion
  • Impact damage making the siding more malleable

Minor warping may be cosmetic. But severe warping can compromise the siding’s weatherproofing and structural integrity. Prevention with proper installation is key.


Composite siding is installed using nails, screws, or adhesive. Over many years and seasonal temperature changes, the siding can begin to detach and come loose. This leaves gaps vulnerable to wind, rain, and pests.

Loose siding must be re-secured. For large affected areas, full replacement may be needed. Using quality fasteners and maintaining the recommended expansion gaps helps prevent loosening.


Cracks can form in composite siding over time. Causes include:

  • Improper spacing between siding boards allowing too much expansion/contraction
  • Impact damage from objects hitting the siding
  • Deformation from underlying structural issues
  • Manufacturing defects present from installation

Small cracks may be purely cosmetic. But larger cracks require patching or siding replacement to avoid moisture intrusion and further damage.

Mold/Mildew Growth

Composite siding discourages mold growth thanks to its moisture-resistance. However, mold can still form under certain conditions:

  • Excessive moisture from leaks, rainwater runoff, or humidity
  • Areas of siding that don’t get direct sun
  • Debris buildup providing food for mold
  • Cracks or gaps allowing water intrusion

Mold is not just an aesthetic problem. It can damage siding and lead to structural issues. Proper moisture control and cleaning are key.

Damaged Sections

Sections of composite siding can become damaged by impacts, animals, severe weather, or improper handling during installation. Damage may involve:

  • Cracks
  • Gouges
  • Holes
  • Breaks
  • Punctures

Damaged areas allow water intrusion that can lead to larger issues. Small holes or cracks can be patched, but larger sections likely need complete replacement.


Delamination occurs when the layers of composite siding separate. It results in bubbles or ridges on the surface that compromise appearance and performance.

Causes include manufacturing defects, underlying structural issues, impact damage, and degradation of bonding agents over time.

Delaminated sections need replacement. Prevention involves using quality products and proper installation.

Preventing Composite Siding Problems

While composite siding is vulnerable to certain issues, you can minimize problems by:

  • Selecting quality products from reputable brands
  • Using experienced installers
  • Allowing proper expansion gaps during installation
  • Installing appropriate moisture barriers behind siding
  • Regular cleaning and maintenance
  • Avoiding impact damage from objects
  • Fixing underlying structural problems immediately

With proper installation, care, and maintenance, quality composite siding will provide decades of durable, low-maintenance performance. Address any issues promptly to get the most out of this innovative product.

Your home’s exterior protection and appearance depend on siding that stands up to the elements. Follow these composite siding guidelines, and you can enjoy beautiful, worry-free performance for years to come.

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