How Much Does Under-Deck Drainage Cost? [2026 Data]

In 2026, the national average cost for under-deck drainage installation is $7,700. Most homeowners pay between $5,100 and $8,000, with the spread driven by deck size, drainage system type, and labor in your area.

Under-Deck Drainage Cost Factors: What Determines the Price?

The cost of under-deck drainage depends on your deck's size, the materials you choose, and labor rates in your area. Here's how each of these factors breaks down.

Deck Size

Your deck's size is the primary driver of under-deck drainage costs, with installation running $21 to $43 per square foot for combined materials and labor. The table below shows how costs vary by deck dimensions

Materials

Your material choice significantly affects the overall project cost, with prefabricated kits like Trex RainEscape, which includes trough panels, downspouts, caulk, and tape, priced at $6 to $8 per square foot. If you source materials independently instead of buying a kit, your cost will depend on which material you select, with options including fiberglass, galvanized steel, and plastic, each carrying a different price point.

Prep

You can install an under-deck drainage system on a new second-story deck or add one to an existing deck, with placement either above or below the joists. Above-the-joist installation is more complex because your pro must first remove the deck boards and railings, which adds time and increases your total cost.

Labor

Labor makes up a significant portion of your under-deck drainage budget, with a local deck builder typically charging $15 to $35 per square foot for their services.

Under-Deck Drainage Ongoing Costs: What to Budget For

An under-deck drainage system is relatively low-maintenance, but you should still budget for a couple of ongoing costs once installation is complete.

Maintenance

Caring for your drainage system as part of routine deck maintenance will help it perform well over time. You can handle annual inspections yourself, but leaks or backed-up water are signs you should call a pro.

Repairs

Like other parts of your deck, your drainage system may need repairs over time, and deck repairs cost $870 to $3,470 on average depending on the specific issue.

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.

Under-Deck Drainage Additional Costs: What Else Should You Budget For?

Adding a drainage system to an existing deck is a smart time to bundle other deck-related projects, since your pro is already on-site and the work can often be coordinated efficiently. Here are a few common add-ons and their costs to factor into your budget.

• Staining a deck costs $550 to $1,250

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

• Deck refinishing costs $900 to $2,720

• Deck painting costs $500 to $2,000

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

• Building an outdoor kitchen costs $6,300 to $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. 

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