Key Takeaways
- Substructure Longevity: Protects timber joists from rot caused by Ontario’s severe freeze-thaw cycles.
- Timing is Critical: Must be installed during a new build or a major rebuild while joists are exposed.
- Precision Slope: Requires a minimum slope of 1/4″ per foot for effective water evacuation.
- Ontario Compliance: Concentrated water discharge must follow local municipal bylaws (e.g., Toronto’s downspout disconnection mandate).
Keeping the area under your deck dry isn’t just about creating a new living space; it’s about protecting your investment. In Ontario, where our deck substructures face extreme freeze-thaw cycles and heavy snow loads, a proper drainage system like Trex RainEscape is the difference between a 15-year frame and a 50-year frame.
This guide provides the technical roadmap for planning, sourcing, and installing Trex RainEscape specifically for the Ontario climate. For a broader look at all available drainage options, visit our Under-Deck Systems overview.
1. What Is Trex RainEscape and How Does It Work?
Trex RainEscape is an above-joist drainage system. Unlike “under-deck ceilings” that catch water after it has already soaked your wood, RainEscape uses a series of troughs and downspouts to intercept water before it touches your joists.
By creating a waterproof barrier on top of the framing, you can:
- Install finished ceilings with recessed lighting and fans (like the RainEscape Soffit Light).
- Keep outdoor furniture and electronics dry year-round.
- Prevent the microscopic wood fracturing caused by trapped moisture freezing inside your joists.
2. Is Trex RainEscape Right for My Project?
Before ordering parts, ensure your project fits the RainEscape profile:
- Ideal For: New deck constructions or “deck skinning” projects where you are removing all old deck boards to reveal the joists.
- Not Ideal For: Existing decks where you do not plan to remove the surface boards. For retrofits, consider an under-joist system like Underdeck Oasis.
- Ontario Living: Perfect for creating “three-season” rooms in the GTA and Ottawa, provided you plan for proper drainage of snowmelt.
3. Step 1: Planning & Measurements
A successful install starts with the “Drainage Map.”
- Measure Joist Spacing: Most decks are 12″ or 16″ on-center. RainEscape troughs are designed for these specific widths.
- Determine Exit Points: Where do you want the water to go? Usually, this is the “rim joist” (the far end of the deck).
- Calculate the Slope: You need a 1/4″ drop per linear foot. If your deck is 12 feet deep, your trough must be 3 inches lower at the downspout than at the ledger board.
- Check Property Lines: In Ontario, you cannot legally discharge concentrated water onto a neighbor’s property. Plan your downspouts to exit into a gutter system that leads to a permeable area of your own yard.
4. Step 2: Parts & Materials Checklist
Avoid the “mid-project hardware store run.” Use this checklist to secure everything from the DeckOutlet Trex RainEscape Collection.
| Component | Purpose | Product Link |
| Troughs | The “gutters” that sit between joists. | Shop Troughs |
| Downspouts | Funnels that transition water to a gutter. | Shop Downspouts |
| Butyl Tape | Seals troughs to the top of joists. | Shop Tape |
| Wall Flashing | Seals the system to your house ledger. | Shop Flashing |
| Butyl Caulk | For sealing complex corners/post gaps. | Shop Caulk |
| Post Flash | Specialized boots for 4×4 posts. | Shop Post Flash |
Pro Tip: For a standard 12′ x 16′ deck, you typically need 13 troughs and 13 downspouts. Always order 5-10% extra tape for overlaps.
5. Step 3: High-Level Installation Steps
Phase 1: Prep & Downspouts
Install the downspout funnels first. Cut them to fit your joist spacing (12″ or 16″) and secure them at the low end of your deck. Ensure the spout extends into your lateral gutter.
Phase 2: The Troughs
Unroll the trough material and let it acclimate to the Ontario air (this prevents “thermal memory” wrinkles). Staple the trough to the ledger board first, then work your way down the joists, establishing your 1/4″ per foot slope.
Phase 3: Sealing (The Most Critical Step)
Apply the RainEscape Butyl Tape over the staples and seams. This tape is self-healing; when you drive your decking screws through it, the butyl “grabs” the screw to maintain a watertight seal.
Phase 4: The Water Test
Never install your decking until you test the system. Run a garden hose at the ledger board for 10 minutes. Check for pooling or leaks. If water stands still, your slope is insufficient.
6. Common Mistakes to Avoid in Ontario
- Failing to Acclimate: Installing cold trough material on a warm day (or vice-versa) leads to wrinkles. Wrinkles trap water. Trapped water breeds mosquitoes in July and creates ice dams in January.
- The “Splicing” Error: Never use two short pieces of trough to cover one long bay. Use a single continuous roll.
- Improper Slope: Gravity is the only thing moving water out of your system. If the slope is too flat, snowmelt will refreeze inside the trough, potentially bursting the seals.
7. DIY vs. Professional Installation
The DIY Path
If you have a single-level rectangular deck and are comfortable with a staple gun and a level, Trex RainEscape is a very manageable DIY project. It requires patience and attention to detail rather than heavy machinery.
The Professional Path (The Deck Store)
We strongly recommend a professional installation for:
- Multi-level decks with complex “picture frame” borders.
- Projects involving under-deck gas heaters or complex electrical.
- Decks where the under-space will be a fully finished “dry room.”
Book a RainEscape Design Consultation with The Deck Store.
8. Where to Buy
The Deck Store’s retail partner, DeckOutlet, stocks the full suite of Trex RainEscape components with fast shipping across Ontario.