Deck Accessories
Drainage
Trex
$5-$12/sq ft installed

Under-Deck Drainage Systems for Dry Outdoor Living Space

Under-deck drainage systems install between deck joists to capture and redirect rainwater, transforming the space below an elevated deck into a dry, usable outdoor area. These trough-and-gutter systems collect water that drips between deck boards and channel it to a designated drainage point. Ideal for two-story decks where the lower level serves as a patio or storage area.

Key Features

  • Ceiling-mount trough panels
  • Integrated gutter system
  • Creates dry space below deck
  • Low-maintenance vinyl construction
  • Compatible with standard joist spacing
  • Optional ceiling finish panels

Specifications

Joist Spacing: 12 in or 16 in OC | Panel Width: 14.5 in or 22.5 in | Material: Vinyl/PVC | Color: White or tan | Slope: 1/8 in per foot minimum | Gutter Size: 3 in K-style

Best For

Elevated second-story decks where the area below is used as a patio
outdoor living room
or storage.

Compatible Materials

Pressure-treated joists
Engineered lumber joists
LVL beams
Composite decking
Wood decking
Metal joist hangers

Pros & Cons

Pros

  • ✓ Creates usable dry space below deck
  • ✓ Low maintenance
  • ✓ Protects patio furniture below
  • ✓ Adds home value
  • ✓ Professional finished appearance
  • ✓ Handles heavy rain

Cons

  • ✗ Requires proper slope for drainage
  • ✗ Professional installation recommended
  • ✗ Higher cost than lattice skirting
  • ✗ Difficult to retrofit on existing decks
  • ✗ Limits access to joist inspection

Installation Tips

Install during deck construction for easiest application. Ensure joists have a minimum 1/8-inch per foot slope toward the drainage gutter. Seal all panel seams with manufacturer-approved caulk. Route the gutter downspout away from the foundation to prevent water pooling near the house.

Frequently Asked Questions