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The Ultimate Guide to Under-Decking Drainage Systems

August 24th, 2023 | 5 min read

By Josh Baynes

under decking drainage systems outdoor living space custom built michigan

Are you tired of seeing your outdoor living space go to waste every time it rains? Are you frustrated with the constant dampness and limited use of the area beneath your deck? If so, you're not alone.

Many homeowners face the challenge of wanting to maximize their outdoor living space while dealing with rainwater runoff, which often renders the area below the deck unusable. The inconvenience of a soggy and underutilized space can be a significant pain point for homeowners who wish to enjoy their outdoor oasis in all weather conditions.

At Custom Built, we understand the struggle of optimizing your outdoor space while facing the limitations caused by rainwater. With over 15 years of expertise in outdoor living space remodeling, we have installed 35 under-decking drainage systems, providing long-lasting solutions to homeowners.

In this comprehensive guide, we will explore the world of under-decking drainage systems, offering insights into various types and their benefits:

What are Under-Decking Drainage Systems?

Under-decking drainage systems are innovative solutions designed to transform the unused space beneath your deck into a dry and functional area. These systems, like gutters, effectively capture and direct rainwater away from the deck, preventing it from seeping through the gaps in the deck boards and causing water damage.

By implementing under-decking drainage systems, homeowners can create an additional outdoor living space that remains usable even during inclement weather. Brands such as Trex RainEscape and DEK Drain have led the way, developing reliable systems that are easily installable.

Disclaimer: Under-decking drainage systems are typically used for raised decks, not ground-floor decks.

Pros of Under Decking Drainage Systems

Under-decking drainage systems offer homeowners a range of advantages, making them a popular choice for transforming underutilized spaces beneath decks into functional and appealing areas. Here are some of the key benefits:

1. Waterproofing and Moisture Control

trex rainescape under decking drainage systems diagram installation guide custom built michigan

PC: Trex RainEscape

One of the primary advantages of under-decking drainage systems is their ability to channel water away from the deck above effectively. By capturing rainwater and melting snow, these systems prevent water from seeping through the deck boards and protect the area underneath from moisture-related issues such as rot, mold, and mildew.

2. Expanded Usable Space

under decking drainage systems outdoor living space with dining table and chairs custom built

With an under-decking drainage system, homeowners gain valuable additional square footage. This newfound space can be utilized in various ways, including creating a sheltered outdoor living area, a play space for children, or a storage area for gardening equipment and outdoor furniture.

3. Enhanced Aesthetics

under decking drainage systems with stairs and firepit outdoor living space custom built

Under-decking drainage systems contribute to a cleaner and more polished look for your outdoor area. By concealing the structural elements and unsightly posts, these systems create a seamless and attractive finish that complements the deck's overall design.

4. Improved Property Value

Investing in an under-decking drainage system can boost your property's value by increasing its usable living space and overall appeal. Homebuyers appreciate the versatility and functionality of a transformed under-deck area, which can positively impact the resale value of your home.

5. Year-Round Enjoyment

Thanks to the moisture protection provided by under-decking drainage systems, homeowners can make the most of their outdoor spaces year-round. Whether it's enjoying summer barbecues without rain interruption or savoring the serene ambiance during rainy autumn days, the under-deck area becomes a versatile retreat for all seasons.

6. Reduced Maintenance

Under-decking drainage systems not only protect the under-deck area from water damage but also minimize debris accumulation. This reduction in debris means less time spent on cleaning and maintenance, allowing homeowners to focus on enjoying their outdoor living space.

By investing in an under-decking drainage system, homeowners can turn what was once a wasted space into an inviting extension of their living area. Whether it's for entertaining guests, spending quality time with family, or simply relaxing in a tranquil environment, under-decking drainage systems offer many benefits that enhance both the functionality and aesthetics of outdoor living spaces.

Cons of Under-Decking Drainage Systems

While under-decking drainage systems offer a range of benefits, there are also some considerations to keep in mind. Understanding the potential downsides can help you make an informed decision about whether an under-decking system is right for your outdoor space.

1. Cost

One of the primary drawbacks of under-decking drainage systems is their cost. Installing these systems typically involves a significant investment, which can vary depending on factors such as the size of your deck and the complexity of the installation.

While creating a dry and usable space beneath your deck can be appealing, the upfront expense might deter some homeowners.

2. Installation Complexity

Installing an under-decking drainage system can be more complex than traditional deck construction. It requires careful planning, precise measurements, and skilled installation to ensure that the system effectively channels water away from the space below. This complexity can also lead to longer installation times than standard decking projects.

Therefore, in many cases, it is better to hire professionals to install your under-decking systems. Their expertise will ensure your system is installed without any detrimental mistakes.

3. Limited Design Flexibility

Under-decking systems can limit the design options for the space beneath the deck. The presence of the drainage system and its components can impact the aesthetics and layout of the area. While some systems offer customizable finishes, there might still be limitations on using the space for various outdoor activities or storage.

4. Noise

Depending on the material used for the under-decking panels, the system might generate noise when rainwater falls on its surface. This noise can be particularly noticeable in heavy rainfall and might impact the tranquility of the space below the deck.

3 Types of Under-Decking Drainage Systems

The primary purpose of under-decking drainage systems is to keep the space below the deck dry and protected. They come in various styles and designs, each with unique features and benefits. Let's explore some of the most common types of under-decking drainage systems to help you better understand how they work and the advantages they offer:

1. Steel Siding Panels Underneath Joists

steel siding panels under decking drainage system outdoor living space

PC: Deck and Drive Solutions

One popular approach involves using steel siding panels placed underneath the deck joists, all supported by wood shims. This method not only effectively channels rainwater away from the deck but also provides a durable and cost-effective option. By strategically positioning steel panels, homeowners can create a seamless and reliable barrier against water intrusion. The steel siding panels are crafted to fit snugly between the joists, ensuring efficient water flow and drainage.

2. Aluminum Under-Decking Drainage Systems

aluminum under decking drainage systems installation outdoor living space

PC: Under Deck Oasis

Alternatively, under-deck aluminum systems like the renowned Under Deck Oasis system have gained significant popularity among homeowners seeking an elegant and practical drainage solution. This advanced system involves installing interlocking aluminum panels beneath the deck surface, creating a waterproof shield that redirects rainwater into a gutter system.

The panels are precision-engineered to seamlessly fit together, ensuring not only efficient drainage but also a sleek and sophisticated appearance. The Under Deck Oasis system offers a versatile and stylish way to transform the area beneath your deck into a functional and inviting outdoor living space while effectively keeping rainwater at bay.

3. Trex RainEscape

trex rainescape composite under decking drainage system diagram troughs and deck boards

PC: Trex RainEscape

Trex RainEscape is yet another innovative under-deck drainage system that has earned a reputation for reliability and performance. Explicitly designed for Trex decking, this system utilizes a network of troughs, downspouts, and trough covers to divert rainwater away from the deck, keeping the area below dry and usable.

Trex RainEscape offers homeowners a versatile solution for maximizing their outdoor living space, enabling them to create cozy seating areas, storage spaces, or even outdoor kitchens beneath their decks. This under-deck drainage system not only adds to the overall functionality of the space but also enhances the value and appeal of the entire property.

Next steps to installing your under-decking drainage system

As a homeowner seeking to transform your under-deck space into a dry, usable area, you understand the challenges of dealing with water intrusion and wasted outdoor space.

The search for the perfect under-decking drainage system has led you to explore various options to create a comfortable and enjoyable space beneath your deck.

After a comprehensive review of under-decking drainage systems, you now have a clear understanding of the different types available, how they work, and their unique benefits.

At Custom Built, we take pride in delivering tailored solutions to enhance your outdoor living experience. With over 15 years of expertise in home remodeling, we understand the importance of maximizing every square inch of your property.

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For more information on under-decking drainage systems and deck remodeling, we recommend the following articles:

Josh Baynes