DECKS + LEDGERS

Preventing Rot, Water Intrusion, and Structural Failure in the Pacific Northwest

What Homeowners Usually Think

“If the deck looks solid and the boards aren’t rotten, everything must be fine.”

What Actually Happens

In the Pacific Northwest, most deck failures don’t start at the boards — they start at the ledger.
The ledger is the structural board that connects the deck to the house, and if it isn’t flashed and detailed correctly, water will work its way behind it and into the home’s framing.
Many catastrophic deck failures begin with hidden rot at the ledger, rim joist, or wall sheathing.

The deck can look perfect while the wall behind it is rotting away.

Why Decks Fail in the PNW

1. Improper or Missing Ledger Flashing

This is the #1 cause of deck rot.
Common mistakes include:

  • No metal flashing

  • Improper lapping

  • Flashing placed behind the ledger instead of over it

  • Nails penetrating the flashing

  • Caulk used instead of proper weather detailing

Every one of these allows water to enter the wall.

2. Ledger Bolted to Rotten or Wet Rim Joists

If the rim joist is compromised, the deck cannot support load safely.

3. Siding Installed Over or Under the Ledger Wrong

If the ledger interrupts the drainage plane, water gets trapped behind it.

4. No Drainage Gap Behind the Ledger

Ledgers should never be tight to the house.
Without a drainage gap, water gets trapped and causes hidden rot.

5. Porch Roofs and Decks Dumping Water Onto the Ledger

Improper roof overhangs, gutters, or downspouts regularly saturate the ledger area.

6. Bare Joist Tops and Beam Tops

Horizontal surfaces soak up water unless protected, leading to premature rot.

7. Incorrect Fasteners

Using non-rated screws or bolts leads to corrosion and reduced load capacity in our wet climate.

Signs of Deck or Ledger Moisture Issues

  • Soft or spongy areas against the house

  • Water staining on siding below the deck

  • Rusting fasteners

  • Mold or fungal growth around the ledger

  • Bouncy, uneven, or sagging deck feel

  • Ants or insects nesting at the ledger

  • Rotting or peeling boards near the house

  • Visible gaps or separation between ledger and house

Most serious problems are hidden behind the ledger.

Best Practices for Decks + Ledgers in the PNW

1. Continuous Metal Ledger Flashing

A properly installed Z-flashing or custom bent flashing that:

  • Extends behind the siding

  • Slopes away from the house

  • Overlaps the ledger

  • Integrates with the WRB

  • Is never penetrated by nails or screws

This is non-negotiable in our climate.

2. Rainscreen Gap or Stand-Off Ledger

The ledger must be spaced away from the house using:

  • ½" spacers

  • EPDM washers

  • Stand-off brackets

  • Rain-screen design

This prevents water from getting trapped and allows drying.

3. Flashing Tape or Liquid Membrane Behind Ledger

We prep the wall with high-quality flashing tape or liquid membrane before installing the ledger.
This protects the sheathing and rim joist from incidental moisture.

4. Correct Fasteners and Structural Hardware

We use:

  • Hot-dip galvanized or stainless steel fasteners

  • Properly spaced ledger bolts or structural screws

  • Simpson Strong-Tie hardware (brackets, hangers, hold-downs)

  • Engineered connectors for uplift and lateral load

No drywall screws. No deck screws into the house.

5. Protected Joist Tops

We install joist cap tape or a sloped-top joist detail to shed water and prolong deck life.

6. Proper Siding Termination

Siding should never be sandwiched behind the ledger.
We cut the siding back and rebuild a proper drainage plane.

7. Gutters and Water Management

We ensure downspouts, roofing, and slope don't dump water onto the deck or ledger.

How Emerald State Contracting Builds Decks That Last

1. Evaluate the Existing Deck Structure

We inspect the ledger, fasteners, rim joist, sheathing, and WRB integration to determine if hidden moisture issues exist.

2. Remove the Ledger and Rebuild the Wall Interface (If Needed)

If the ledger is improperly installed or rot is present, we:

  • Remove siding around the ledger

  • Repair rim joists or sheathing

  • Rebuild the drainage plane

  • Install proper flashing

  • Reinstall or replace the ledger safely

3. Install a Stand-Off or Rainscreen Ledger System

This is the PNW building-science standard for preventing rot.

4. Use Full Simpson Strong-Tie Hardware

Proper joist hangers, lateral load connectors, and stainless-rated hardware ensure structural integrity.

5. Flash and Protect All Horizontal Surfaces

We protect joist tops, beam tops, and connection points with membranes or caps.

6. Rebuild the Deck with Modern, Durable Assemblies

We choose materials and details that maximize lifespan, drainage, and structural safety.

Why This Matters

Deck and ledger failures are:

  • hidden

  • dangerous

  • expensive

  • preventable

A PNW deck built with proper moisture management can last 30–50 years.
A poorly flashed ledger can rot out the house in less than 10.

When to Call a Professional

You should have your deck evaluated if:

  • The deck is more than 10–15 years old

  • You’re planning a deck replacement or expansion

  • You notice soft spots or sagging

  • You see stains or mold near the ledger

  • The deck is attached to stucco, brick, or fiber cement siding

  • You plan to enclose or roof the deck

  • You’re unsure how the ledger was installed