Restoring a Residential Balcony, Putting a Stop to Moisture Problems

Restored residential balcony using Cem-Rock and Stone Edge Surfaces Pro Stamp Mix
The restoration of a residential balcony completed showing textured finish with Stone Edge Surfaces, Pro Stamp Mix.

A waterproof balcony is a common amenity for custom homes, condominiums, and resort properties. Solid surface balconies are easy to maintain. They also ensure proper stormwater drainage away from the building while protecting outdoor patios below deck.

New home designs, including building renovation projects, may include a waterproof balcony. This is especially true if the building faces natural features such as a mountain range, a lake, river, or a coastline. It’s only natural to note that these surfaces catch the brunt of wind-driven rain and snow, and exposure to high humidity in many parts of the country. That said, the balcony remains one of the ultimate gathering places for
outdoor entertainment or that early morning coffee at sunrise.

Moisture Damage Hiding In Wait

Perched along Florida’s Atlantic coast is a residence that has seen its share of weather events and exposure to the elements. What was unexpected was a serious moisture-related problem hiding below the surface of the 5/4 decking laying atop rolled asphalt roofing. Water leakage appeared through the ceiling below.

After removing the wood decking, the problem was discovered when stepping on the balcony started feeling spongy. It wasn’t until the homeowner stepped onto one of those soft spots that his foot went through the deck, and he found himself standing between rafters on the ceiling of the patio below. In this way, dry rot was discovered.

The restoration of the residential balcony started with the removal of the dry rot plywood Moisture issues caused damage in the residential balcony project
The balcony required the removal of rolled roofing and plywood once dry rot was discovered. Much of the area of dry rot was a result of moisture intrusion.

Dry rot is commonly the result of improper ventilation or of moisture intrusion caused by poor construction methods, inferior building materials or deterioration of an existing building finish. Dry rot can lead to a host of health-related problems as well as the loss of a building’s structural integrity.

Fixing the Dry Rot Problem

In the case of this single-family residence, it was determined that the entire residential balcony subfloor would need to be replaced, including several of the supporting 2”10” floor joists.

Ralph Schoenherr, a retired public infrastructure professional with an affinity to restoring classic cars, gave special attention to this project, in part because it was his daughter’s home.

Determined to find a better building material, Ralph’s online search led to a building material known as Cem-Rock eXtrme Subfloor ¾”. The material is new to the US market, and more commonly referred to as MgO board, for magnesium oxide board. Unique to this material is its hydrophobic characteristics, which got immediate attention. The fact that Cem-Rock is also fireproof made it even more appealing.

Installation of Cem-Rock eXtreme Sub-floor installed and ready for waterproofing system.

As Ralph explains, over time moisture will find its way in, and it’s hard to identify a problem until it’s too late, especially with minimal slope. Even treated wood products, once the material is saw cut and perforated with fasteners like nails, screws or staples, create endless opportunities for moisture intrusion. CemRock eXtreme Floor ¾” MgO, on the other hand, will never deteriorate in the presence of moisture.

The plan for success

From the outset, Ralph was interested in using a cementitious waterproofing system for the residential balcony. That search led to the, where products by Stone Edge Surfaces were found, including the Cem-Rock eXtreme Subfloor product.

As Ralph explains, a phone conversation with the store’s owner, Bent Mikkelsen, involved a lengthy discussion about the benefits of using Cem-Rock in place of a plywood material. Among the aforementioned benefits of Cem-Rock, the need for a vapor barrier and diamond lathe when using plywood would not be required. Not using diamond lathe eliminated the need for staples to hold the lathe in place. In fact, code requires staples to be installed two inches apart. That’s a lot of staples! Ralph states that the beauty of using Cem-Rock and Stone Edge products is that it allows for scheduling flexibility of the project stages.

Application of Primer 100 following the application of Pro Bond Ultra.

Instead, Stone Edge Deck Resin was roller-applied to the surface of the Cem-Rock and fiberglass mesh embedded into the wet surface. A second, wet-on-wet coat of resin was then applied and followed with the broadcast of a 30-mesh silica sand to refusal. The use of silica sand creates a coarse sandpaper type of surface that gives a topical coating something to hold onto.

The next day, the excess sand was removed with a leaf blower before a 1/8” coat of the Stone Edge Pro Bond Ultra was applied. It rained that night, but had no effect on the curing of the Pro Bond Ultra. A gentle breeze the following morning dried the deck quickly so that a bond coat of Stone Edge Primer 100 could be applied.

The deck was now ready for a 3/8” layer of the Pro Stamp Mix. Christi Tamayo of Select Surfaces Solutions in Orlando provided support with the use of their texturing skins, used to create a natural stone finish before the Pro Stamp Mix hardened.

Spreading the Pro Stamp Mix along the surface of the residential balcony using a gauge rake to ensure a consistent 3/8″ material depth.
The Finishing Touch

With the balcony project nearly complete, the final step was the application of a water-based concrete sealer. Because the homeowner wanted the balcony color to closely match the color of their wood boat dock, they mixed Stone Edge Surfaces liquid color pigment (bronze) with Pro Seal and roller-applied. Two color-coats of Pro Seal, in addition to a coat of Pro Seal without color added, produced a natural matte
finish. The balcony renovation was now complete.

Ralph and Paul texturing the Pro Stamp Mix with slate texture embossing tools

As Ralph explains, once they installed the Cem-Rock eXtreme Floor, the deck felt like you were stepping onto a concrete surface. With the cementitious waterproofing system applied to the surface, it gave the residential balcony a really solid feel while adding aesthetically to the home.

“We feel we have eliminated the potential for moisture problems in the future, and my daughter’s family can now enjoy their balcony for years to come.”

Coming Soon: How Cem-Rock eXtreme ¾” MgO board is used on multi-family construction projects to minimize insurance claims associated with faulty washing machines and dishwashers. Cem-Rock eXtreme ¾” (MgO) boards include an added level of fire protection and sound proofing to multi-family residences.

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