How Much Does Under-Deck Drainage Cost? [2025 Data]

Under-Deck Drainage Cost Factors

Several factors impact the cost of under-deck drainage, including your deck’s size, the materials used, and labor prices in your location. Here’s an overview of the main factors.

Deck Size

Your deck’s size greatly affects the cost of under-deck drainage. For materials and labor, installing this type of drainage system runs between $21 and $43 per square foot. Here’s how much it would cost to add under-deck drainage for various deck sizes.

Materials

Prices also depend on the materials you choose. For example, Trex RainEscape is a well-known under-deck drainage system. It includes a range of products, such as trough panels, downspouts, caulk, and tape. According to the company, the Trex under-deck drainage system costs $6 to $8 per square foot.

However, prices will vary if you buy your own materials instead of purchasing a kit. The cost to build a DIY under-deck drainage system depends on the specific materials you choose. Fiberglass, galvanized steel, and plastic are a few options to consider, all of which vary in price.

Prep

While some people choose to install drainage when building a second-story deck, you can also add a drainage system to an existing deck—either above or below your deck joists. 

Installing a drainage system above the joists is more complicated and time-consuming. Your pro will first need to remove the deck boards and railings, which requires additional time and increases your costs.

Labor

Labor accounts for a significant chunk of the cost to install under-deck drainage. On average, a local deck builder will charge between $15 and $35 per square foot for their services. 

Under-Deck Drainage Ongoing Costs

An under-deck drainage system doesn’t require much upkeep, but there are a couple of ongoing costs you could face after installation.

Maintenance

After installing your drainage system, it’s important to take care of it as part of your routine deck maintenance. You can perform annual deck inspections on your own, but if you notice any leaks or backed-up water, bring in a pro to fix the drainage system.

Repairs

Like the other parts of your deck, your under-deck drainage system may require repairs from time to time. The price depends on the specific issue, but on average, deck repairs cost $870 to $3,470.

Why You Should Hire a Drainage Pro

A local drainage pro charges $21 to $43 per square foot for labor and material for underdeck drainage systems. Most homeowners find that hiring a drainage installation company can ensure proper and efficient under-deck drainage.

Here’s why it’s ideal to hire a drainage installation pro

Underdeck drainage is best installed by a pro for many reasons, including:

• Above-the-joist installation is complex and time-consuming.

• Local drainage pros with insurance can protect you from any errors that may happen during the installation.

• Many pros offer discounted services for the first year of maintenance after installation.

• Combining drainage installation with new patio construction will save time and money.

If you want to DIY an underdeck drainage

If you have deck-building experience, you can try to install underdeck drainage yourself:

• Choose under-the-joist installation since it is easier to install

• Use prefabricated drainage kits.

• Find a handy friend to help you with the installation.

• When building a new deck, plan your underdeck drainage system well in advance.

Cost of Common Under-Deck Drainage Add-Ons

If you’re adding a drainage system to an existing deck, it’s a good opportunity to tackle other deck-related projects, too. Here are a few common add-ons to consider: 

• Staining a deck costs $550–$1,250

• Sealing or waterproofing a deck costs $500–$1,400

• Deck refinishing costs $900–$2,720

• Deck painting costs $500–$2,000

• Installing outdoor lighting costs $2,000–$6,000

• Building an outdoor kitchen costs $6,300–$26,900

How to Save Money While Installing Under-Deck Drainage

Adding an under-deck drainage system can get pricey—especially when you hire a professional. However, there are a few possible ways to cut costs on this project, including: 

• Doing your own prep work: You could reduce labor costs by preparing the deck for installation before your contractor arrives. For example, you could clean up leaves and debris from the deck or move any outdoor furniture so that they can get straight to work. If you’re comfortable with it, you could even remove the deck boards and railings, but be careful not to damage them.

• Planning your project for the off-season: For decking pros, work often slows down in winter, and contractors may offer lower prices then. By scheduling your project during the slower season, you could get a better deal.

• Shopping around: It’s a good idea to request quotes from at least three professionals before hiring someone. This helps you compare pricing and ensures you’re paying a fair rate.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

Want to help us improve our cost data? Send us a recent project quote to [email protected]. Quotes and personal information will not be shared publicly.