How to install a drainage system under your composite deck
Technical note: Installation details vary by municipality, product line, board profile, fastening system, loads, and site conditions. Use this article as general guidance only; confirm the final design with your local building department, the manufacturer's current installation guide, and a qualified contractor or engineer when structural loads are involved.
Installing a composite deck from brands like Fiberon, Trex, TimberTech, or TruNorth is a top choice for a durable outdoor living space in Quebec. However, without proper drainage, rainwater can seep through and render the area under your deck unusable. Discover how an "over-the-joist" under-deck drainage system protects the structure and creates a dry patio.
Why choose over-the-joist drainage
Systems installed before the deck boards offer several advantages:
- Maximum Protection: Prevents water from touching the joists, avoiding rot and corrosion.
- Flexible Layout: Allows for the addition of a ceiling under the deck to install lights or a fan.
- Certified Compatibility: Designed to work with Fiberon, Trex, TimberTech, and TruNorth ranges.
"An over-the-joist system maximizes the longevity of your composite deck while providing a usable space underneath." - Michel Gagné, outdoor living expert
Materials and tools required
- Trex RainEscape Kit (drainage troughs, profiles, and butyl tape)
- PVC or aluminum gutter
- Butyl sealant
- Nailer or stapler and staples
- Jigsaw or hacksaw
- Cordless drill/driver and self-tapping screws
- Measuring tape and marking pencil
Installation steps
Follow these general guidelines to install an under-deck drainage system for your composite deck in Quebec:
- 1. Position the troughs: Install one trough per joist bay (12" or 16" OC spacing). Cut according to joist height and staple each trough to the perimeter beam.
- 2. Install the profiles: Slide the profile under the wall flashing and fasten it to the top of the joists.
- 3. Install the gutters: Unroll the V-shaped membrane to direct water towards the troughs. Staple it along the joists, maintaining a slight slope.
- 4. Seal the joints: Apply butyl tape over overlaps and around screws for perfect waterproofing.
- 5. Attach the main gutter: Align it under the troughs with a slope of approximately 1/8" per foot to ensure proper drainage.
- 6. Install composite deck boards: Use a hidden fastening system compatible with Fiberon, Trex, TimberTech, or TruNorth. The butyl tape protects fasteners against infiltration.
Benefits for your deck in Quebec
- Increased Durability: Eliminates water stagnation and extends the life of the structure.
- Optimal Comfort: Dry space to install a finished ceiling under the composite deck.
- Added Value: A well-designed patio increases the appeal and value of your property.
Ready to transform your outdoor space?
Our dedicated team at Magasin de Patio will help you choose the right drainage system and composite materials for your project. Benefit from our expertise for an outdoor living space that meets your expectations.