Indoor Pool Room that Mitigates Moisture Issues

Many homeowners go to to great lengths to keep water out of the home, but Abel and Laura Martinez of Hoover, Alabama, added a wing to bring the water inside.

The new room built onto the rear of their house was designed to contain a hot tub/infinity pool for a relaxing place to take a dip and get some exercise.

A massive concrete block foundation supported the pool. Heavy steel framing supported the house extension and its surrounding deck. The interior construction, however, is what caught the attention of the HIR staff. To manage the moisture of the indoor heated pool, the Canopy Construction crew employed a few techniques not often seen in residential remodeling.

Waterproof Walls

When it comes to building interiors, the choices are limited regarding which materials can withstand prolonged contact with moisture—airborne or otherwise. Most wood will swell, cup, or bow if it gets wet, while damp drywall will develop mold and mildew. For this reason, ceramic tile is a leading option for kitchens and bathrooms. Although it holds up to water, tile can be expensive to purchase and have installed, and the new wing addition had a lot of area to cover.

To prevent moisture problems inside the pool room, the builders installed fiber-cement HardiePanel siding over the ceiling joists and wall studs.

To balance cost with the need to mitigate any moisture problems, the Martinezes decided to cover the room's wall and ceiling framing with cement board. Often used as house siding or as tile backerboard, cement board is sold under brand names such as Hardie and Durock.

For any readers unfamiliar with the material, cement board is a combination of cement and reinforcing fibers formed into sheets, 1⁄4 to 1⁄2 inch thick. Cement board is stronger and more impact-resistant than water-resistant gypsum drywall. The boards can be nailed or screwed to wood or steel studs, and on this project the material was used as the finish system itself.

The boards are available as 4-by-8-ft. panels and also in trim boards of varying sizes. On this project, the rectangular Hardie trim boards were used to cover all the seams between panels, which gave the walls and ceiling the look of board-and-batten trim. Not only did this present an attractive option for the interior decor, but the cement board is 100-percent waterproof, resists cracking, rotting, swelling, damage from mold, and even comes primed for paint.

Any irregularities in the framing can mirror through the finished cement board, so correct any problems before installing the panels.

The fiber-cement siding is available in primed 4x8 panels which can be cut to size. Cement board may be cut with a carbide-tipped scoring knife, utility knife or cutting shears. If you use a grinder or circular saw, be sure to cut outside and use a Hardieblade intended for fiber cement.

The panels can be nailed into studs or solid framing with corrosion-resistant fasteners. James Hardie recommends the use of quality, hot-dipped galvanized nails.

The seams between panels were covered with 3-1/2-in. fiber-cement trim strips. The frame sections created by the trim boards gave the ceiling and walls a board-and-batten style pattern.

The caulk and paint selections for the pool room contain mildewcide to perform well in damp environments.

Waterproof Flooring

The floor of the Martinez extension was a major concern because in addition to contact with steam and condensation, it would collect all the splashes and drips that result from using the pool.

The first step in protection was to cover the subfloor with Ice & Water Shield, which is a waterproof underlayment membrane developed to protect vulnerable areas on a roof from water damage. The installers covered the entire subfloor with rolls of Ice & Water Shield, abutting the edges for a flat, continuous subsurface for the finished floor.

The subfloor was covered from wall to wall with a protective layer of Ice & Water Shield.

The next step called for installation of 100-percent waterproof flooring. Available exclusively from Floor & Decor, NuCore flooring looks and feels like wood but can be installed where real wood would fail. It comes ready to install right out of the box with no acclimation time needed. NuCore is a "luxury vinyl" product with a rigid core and cork bottom layer, which is soft underfoot and sound resistant.

The planks assemble into a floating floor and are easy to install even for a DIY'er. No nails or glue are required. Begin by laying the first plank on the left side of the wall, leaving a 1/2 inch expansion gap. Install the next plank at an angle, clicking the tongue-and-groove joint into place. Use a hammer and tapping block to tap the end joints closed and continue down the row. To fit the last plank in the row, measure and score with a utility knife, then snap the plank along the cut.

Pro-Tip: Jeremy Harris of Complete Quality Flooring (205-830-7392) custom-shapes his tapping block with a scraper so the block has the tightest fit against the flooring he will install.

Start the second row with a leftover plank at least one foot long. Insert the tongue into the groove of the first row, then tap it into place to close the joint and eliminate any gaps between the long sides. Stagger the planks and continue until you reach the last row.

The last row should be at least two inches wide and often needs to be cut to width. Measure and rip the last row to fit, then insert the cut planks against the wall.

The expansion gaps around the flooring can be concealed with molding or trim.

The block protects the boards as a hammer-tap closes the joints.

Begin each new row with the cut-off plank from the previous row so the joints are staggered between rows.

Dealing with Humidity

The Martinez pool room was designed with sliding patio doors and more windows than wall space. On warm days, the 72-in. windmill-style ceiling fan and the open windows create ample airflow to help dispel the room's humidity and keep the living space fresh and comfortable. The pool also stays covered when not in use.

But what about very cold days? To help manage humidity when the pool is uncovered and the windows are closed, the Martinezes use a commercial dehumidifier. To eliminate mold, mildew, and their associated odors, the Quest HI-E Dry 120 dehumidifier can be used stand-alone or in ducted installations for areas with heavy moisture loads.

Take a Dip

Once completed, the new pool room was a beautiful sight to behold. The centerpiece: The dual zone FX219s swim spa, which features a 5-seat hot tub and a spacious swim spa in one unit. You can operate both zones at once, or use only the hot tub or only the swim spa, depending on the season and your lifestyle.

It's powered by six jets and provides ample space for a full-stride swim routine, so Abel and Laura can kick back and relax, or put in a good workout.

Don't you want a pool room, too?