Protect Your Deck Substructure: Flashing & Joist Covers Made Simple

When building a composite deck, protecting the deck substructure from moisture is essential. Deck flashing and joist covers are two simple, affordable tools that keep your joists and ledger board safe, ensuring your deck remains strong, safe, and long-lasting.

In Part 3 of our How-To Composite Decking Video Series, we cover two essential products that make safeguarding your deck simple, affordable, and efficient: plastic joist covers and plastic flashing.

Plastic Joist Covers: Fast & Effective Protection

Derek installing black plastic joist covers to protect deck substructure from moisture

Wood joists are the backbone of your deck—but they’re also highly vulnerable to moisture damage. That’s where Armadillo’s 8-foot black plastic joist covers come in.

  • Shields joists from water exposure

  • Extends the lifespan of your deck’s frame

  • Up to 70% faster to install than traditional joist tape

Armadillo black plastic joist covers for protecting deck substructure from water damage

With Armadillo joist covers, you’ll save time without sacrificing quality or protection.

Deck Flashing & Ledger Board Protection

Armadillo black plastic deck flashing for protecting ledger boards from moisture

The ledger board—where your deck connects to the house—is one of the most critical (and at-risk) areas of your deck. Without proper protection, water can seep in, leading to:

  • Rot

  • Structural failure

  • The deck pulling away from your home

That’s why plastic flashing is a must. Armadillo’s flashing is:

  • Easy to install

  • Up to 50% less costly than competitor products

  • Corrosion-free compared to traditional metal flashing

Plus, most building codes require deck flashing at the ledger board—making this step essential for both safety and compliance.

Why Deck Flashing & Joist Covers Matter

Rotted wooden deck joists showing damage from moisture without flashing or joist covers

Taking just a few extra minutes during installation to add joist covers and ledger flashing can add years to your deck’s life. By keeping moisture out of the substructure, you’re protecting your investment and ensuring your deck remains safe, sturdy, and beautiful for decades to come.

Pro Tip: Pair joist covers and flashing with Armadillo Composite Decking for maximum protection and a deck that’s built to last.