How a Deck Rebuild in Ooltewah Added Usable Square Footage Without Adding a Single Room
A case study on the Trex RainEscape Under-Deck Drainage System and what it actually means for homeowners in East Tennessee
There is a space underneath a lot of elevated decks in the Chattanooga area that homeowners never think about. It is technically there. It is protected on three sides. It has potential. But the moment it rains, it becomes a wet, muddy, unusable patch of ground that nobody wants to be near.
That was exactly the situation for a homeowner in Ooltewah, Tennessee, who reached out to Armor Xteriors for a full deck rebuild. The existing deck had run its course structurally, and the space below it had never been anything more than a storage area for things the family did not really want to look at. When the weather turned, even that stopped being practical.
The solution was not just a new deck. It was a complete rethinking of what that space could be, using a product built specifically for this problem: the Trex RainEscape Under-Deck Drainage System.
The Problem? 51 Inches of Rain Per Year and a Deck That Ignored All of It
Ooltewah gets roughly 51 inches of rain per year, well above the U.S. average of 38 inches. Precipitation hits the area on approximately 99 days out of the year, which means that for more than a quarter of all days on the calendar, rain is a factor in whether or not an outdoor space is usable.
For a homeowner with an elevated deck, that math is brutal. Traditional deck construction channels water directly down through the decking, through the joists, and onto whatever is below. There is no redirection. No management. The space below the deck gets as wet as open ground, sometimes wetter because the deck above concentrates water flow in specific channels.
The result is a space that is unusable for a significant chunk of the year, contributes to moisture damage on the deck substructure over time, and sits as a wasted opportunity in the most-used part of the home’s outdoor square footage.
For this Ooltewah family, the area underneath their deck had never been anything. The rebuild was the chance to change that.
The Solution: Trex RainEscape Under-Deck Drainage System
The Trex RainEscape system is an under-deck drainage system installed between deck joists before the decking boards go down. It is made up of a network of troughs and gutters that captures water coming through the deck boards above and channels it to downspouts at the edge of the deck, directing it completely away from the space below.
The system provides 100% protection of the deck substructure from moisture. That is not marketing language. That is the product specification from Trex. The troughs are made from 20-mil material, installed between joists at a slight slope to move water efficiently toward the downspouts, and sealed with butyl tape at all overlaps and connections.
The product is tested to perform in temperatures ranging from -40 degrees to 165 degrees Fahrenheit, which means it handles Tennessee summers and the occasional ice event without issue. It comes backed by a 25-year warranty directly from Trex, and when installed by a certified Trex contractor, that warranty is further reinforced by the installer’s coverage.
For the Ooltewah project, Armor Xteriors installed the RainEscape system as part of a complete deck rebuild, meaning the substructure was fresh, the joists were clean and properly sloped, and the system was integrated from the ground up rather than retrofitted. That matters. A properly sloped installation with sealed overlaps performs significantly better than a system added after the fact to an existing structure.
What Changed: Square Footage Without Construction
This is the part of the Trex RainEscape story that does not get talked about enough.
Adding a room to a home costs, on average, between $80 and $200 per square foot in Tennessee, depending on the type of construction, finishes, and permitting involved. A 200-square-foot addition could run anywhere from $16,000 to $40,000 or more, and that does not account for the time, disruption, or permitting process.
The under-deck space in this Ooltewah project was approximately 200 square feet. Before the rebuild, it was a wet, underutilized area. After the Trex RainEscape installation, it became a fully protected, weather-independent outdoor living space capable of housing seating, lighting, ceiling fans, and entertainment equipment.
The family did not add square footage to their home in the traditional sense. But they gained functional, usable space that had never existed before. The cost of the RainEscape system itself runs roughly $2.50 to $4.00 per square foot installed, a fraction of what traditional square footage costs to add.
That is a meaningful financial equation for any homeowner evaluating how to expand their usable living space.
How the Installation Works
For anyone considering this system, it helps to understand what the installation actually involves, because it directly affects the quality of the outcome.
The troughs are installed between deck joists before the decking surface is laid. Each trough is 19-5/8 inches wide, sized to fit snugly between standard joist spacing. Butyl tape is applied at all overlaps and seams to prevent water from bypassing the trough. The troughs are stapled into place every few feet and maintain a slight downward slope toward the downspout locations at the deck’s edge.
The downspouts are positioned to move water away from the foundation and the space below. Once the decking is installed over the top, rain that comes through the boards above hits the trough surface, follows the slope, and exits through the downspouts cleanly. The space below stays dry.
On the Ooltewah project, the integration with a full deck rebuild meant the joists were set with the slight slope already accounted for, and the downspouts were positioned as part of the overall design rather than added as an afterthought. That kind of planning-forward approach is one of the advantages of doing a full rebuild versus attempting a retrofit.
The Broader Case for Under-Deck Drainage in East Tennessee
Ooltewah is not unique in this region. The entire Chattanooga metro, including surrounding communities in Hamilton County, gets weather patterns that make under-deck drainage genuinely practical rather than optional for elevated decks.
The area averages over 150 days per year with some form of precipitation. Summers are hot and humid, with afternoon thunderstorms that are common from June through August. The deck surface itself may dry quickly, but without a drainage system underneath, the substructure and the below-deck space absorb moisture repeatedly throughout the season.
Over time, that moisture exposure degrades wood substructures, creates conditions for mold and mildew growth, and turns a potentially useful outdoor space into a maintenance liability. A system like Trex RainEscape addresses all three of those problems simultaneously by removing moisture from the equation entirely.
The 25-year warranty on the system also means that for the life of the deck itself, the homeowner has coverage on the drainage performance. That is a long-term assurance that most home improvement products cannot offer.
The Result
The Ooltewah homeowners went from a worn deck and a useless, weather-exposed space below it to a new Trex deck above and a dry, functional outdoor area underneath that they can actually use year-round.
They did not build an addition. They did not add to the footprint of their home. They recovered square footage that was already there and had simply never been protected.
For homeowners in the Chattanooga area sitting on an elevated deck with unused space below it, this project is a practical illustration of what is possible. The combination of a quality deck rebuild and the right drainage system changes the math on what outdoor living space can look like.
Armor Xteriors is a Trex ProPlatinum certified contractor serving Chattanooga, Ooltewah, and surrounding communities in East Tennessee. To learn more about deck rebuilds and Trex RainEscape installations, visit ArmorXteriors.com.
