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Fill Out Deck Packages with Under-Deck Drainage

Sometimes it’s what clients don’t see that they appreciate most. An under-deck drainage system is a perfect example. While not something homeowners typically know to ask for, these systems add tremendous value to any deck project and...

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Sometimes it’s what clients don’t see that they appreciate most. An under-deck drainage system is a perfect example. While not something homeowners typically know to ask for, these systems add tremendous value to any deck project and practically sell themselves once their benefits have been explained.

Advantages of Adding an Under-Deck Drainage System

Using a network of troughs and downspouts, a deck drainage system captures and diverts water away from a deck to protect the substructure from moisture and to a create dry, usable space beneath an elevated deck. These systems act like shingles on a roof to shield the wooden foundation from moisture penetration and damage. Without protection, an average wood substructure can begin to deteriorate after just 10 years, while a deck drainage system can extend the life of a deck and its framing for decades.

Once protected, the area below the deck surface can be used like any room inside a house. Homeowners can add electricity, water and gas lines, as well as furniture, lighting, ceiling fans and entertainment components to create additional outdoor living space.

This area also is ideal for use as bonus storage space for stowing everything from lawn and garden equipment, pool supplies and off-season patio furniture to bicycles, boats and ATVs. With a drainage system in place, the possibilities are limitless for how the space below a deck can be used.

Under-Deck Drainage Systems Options & Differences

While there are numerous options for under-deck drainage systems with various configurations, components and price points, these systems largely fall into one of two categories—those that are installed beneath the substructure framing, and those that are applied above the joists.

Below-the-joist systems consist of metal or vinyl panels retrofitted to the underside of deck’s joists with the panels sloping to a gutter installed at the deck beam for drainage.

Advocates of this type of system will tout that installation does not require the dismantling of an existing deck. However, these systems are best installed by specialized contractors so dismantling shouldn’t ever be an issue.

A disadvantage of systems that install below the joists is that they leave wood and metal exposed to the elements and more susceptible to water damage and corrosion. This type of system can also trap moisture in the core supports of the substructure, which can accelerate rotting and deterioration.

For optimal protection and aesthetics, most contractors prefer drainage systems that install above the joists between the substructure and the deck boards. This method uses poly or rubberized membranes that drape over the joists and down into each joist bay from above the substructure, ensuring that the entire substructure is shielded from moisture penetration. Furthermore, the membrane material (vs. metal, vinyl or PVC) accommodates a broader range of ceiling options for homeowners seeking a finished aesthetic.

In both cases, deck drainage systems are relatively simple to install and require minimal tools. Trex RainEscape, for instance, is an above-the-joist system that includes just five SKUs and can be installed using just a stapler, utility knife and caulk. Each trough is clearly labeled with staple markers to expedite the process, which takes no more than a few hours to complete, depending on the size of the deck.

An Upgrade to Drive Customer Satisfaction, Revenue and Referrals

An under-deck drainage system is an upgrade that allows builders to drive increase profit potential without having to hire additional employees. Assuming a margin of 20% on a 325-sq. ft. deck, a builder can potentially earn a few thousand dollars more by adding an under-deck drainage system to a project. Over the course of a year, these minor increases can have a major impact on the bottom line.

The best part is an under-deck drainage system is an upgrade that builders can feel confident selling. While it may increase the cost of a deck project, most homeowners feel it is well worth the investment—especially after the first rainfall when they experience firsthand the value of having a dry outdoor living space they can enjoy even in inclement weather. Additionally, protecting the structural integrity of their deck’s substructure affords homeowners peace of mind and satisfaction that can lead to referrals and more business.

– Dave Kile is founder of and national sales manager for Trex RainEscape (