If you’ve started researching how to keep the space under your deck dry, two names come up constantly: Trex RainEscape and Admiral SpaceMaker. Both solve the same underlying problem – water passing through deck boards and damaging the structure below – but they take fundamentally different approaches to get there. Understanding that difference is the key to choosing the right system for your project.
Two Different Approaches to the Same Problem
Trex RainEscape is an under-deck drainage system. It installs as a network of troughs that sit above the joists, beneath standard deck boards, catching water as it passes through the gaps between boards and channeling it to gutters and downspouts at the deck’s edge. The deck surface itself – typically Trex composite decking or similar gapped boards – still lets water through; RainEscape’s job is to manage that water once it’s already below the decking.
SpaceMaker takes the opposite approach. Instead of managing water after it passes through the deck, the boards themselves are solid-core PVC with a continuous Super Seal gasket running the length of every joint. Water never gets past the surface to begin with, so there’s no troughs, no downspouts, and no separate drainage layer to install or maintain.
Same goal – a dry space underneath your deck. Different point of attack.
How They Compare
Where the water is stopped RainEscape stops water above the joists but below the deck boards, using a poly trough system, butyl tape, and caulked seams to manage the water once it’s already through the decking. SpaceMaker stops water at the deck surface itself, using a single mechanical gasket seal between boards, so there’s nothing for water to reach below the deck in the first place.
Installation RainEscape is genuinely the easier system to retrofit onto an existing deck without major demolition when installed as an undermount system below the joists – though Trex’s own documentation notes that an overmount installation (the version with the 25-year warranty) requires removing the existing deck boards, railings, and any structures like pergolas first. Trex estimates a drainage system installation at $6–$8 per square foot and 1–2 days of labor. SpaceMaker, by contrast, replaces the deck boards themselves, so it’s most efficient on new builds or full deck replacements – and because the boards are solid PVC rather than open composite, installers note it requires more attention to ledger flashing and slope than typical decking.
What’s underneath when you’re done With RainEscape, the underside of the deck is the trough-and-gutter system itself – functional, but it’s still a drainage apparatus, and Trex’s own materials note the sloped channels remain visible unless a separate finished ceiling is added. With SpaceMaker, the underside of the deck boards is the finished ceiling. There’s no separate system to look at, though many homeowners still choose to add a dedicated ceiling product purely for aesthetic reasons, not because the structure needs one.
Long-term maintenance RainEscape’s troughs depend on staying clear of debris and properly sloped to keep draining correctly over time – a faulty installation or trapped debris can accelerate water damage rather than prevent it. SpaceMaker’s seal has no moving parts and nothing to clean or re-slope; the boards either seal correctly at installation or they don’t, with no ongoing drainage system to maintain.
Cost This is where RainEscape has a real advantage, and it’s worth saying plainly: a drainage system added to an existing gapped deck is generally less expensive than replacing the deck surface entirely with solid-core watertight boards. SpaceMaker is a premium decking product, and the upfront cost reflects that. The tradeoff is what each dollar is buying – a system that manages water after the fact, versus a deck surface where rot, mold, and joist moisture from water infiltration simply aren’t a factor.
Which One Fits Your Project?
If you already have a deck you’re happy with and just want to dry out the space underneath without replacing the decking, an under-deck drainage system like Trex RainEscape is a reasonable, well-established option – particularly for budget-conscious retrofits.
If you’re building new or planning a full deck replacement, and you want the water problem solved at the source rather than managed after the fact, that’s where a watertight deck system like SpaceMaker earns its place – especially for second-story decks, enclosed outdoor living spaces, or any project where you don’t want long-term reliance on a drainage system staying clear and properly sloped.
See the Difference for Yourself
The clearest way to understand how SpaceMaker’s sealed-board approach differs from a trough-and-gutter system is to see and feel it in person. Request a free SpaceMaker sample and take a close look at the Super Seal gasket, the solid-core construction, and the finish – no cost, no obligation, just a firsthand comparison before you decide which approach is right for your deck.
Trex® and Trex® RainEscape® are registered trademarks of their respective owners. This comparison reflects publicly available product information at the time of writing and is intended to help homeowners and builders understand the structural differences between drainage-based and surface-sealed deck systems.