When a deck or balcony sits above living space, a garage or a walkway, the walking surface has to do more than look good. It has to keep water out of the structure for years at a time. The Westcoat ALX Pro system is the waterproof deck coating we install on decks, balconies, landings and covered porches across Vancouver WA and the Portland metro.
This guide explains what ALX Pro is, how it is built, why it is waterproof and fire rated, and what the manufacturer warranty covers. The technical details come from Westcoat's published ALX Pro Standard Finish system specification.
What ALX Pro Is
ALX Pro is a bonded, waterproof walking deck system. It combines a reinforcing lath, a fiberlath-reinforced membrane and a series of polymer-modified cementitious coats, sealed with Westcoat's SC-10 acrylic topcoat. The finished system weighs approximately 2½ pounds per square foot and gives plywood the look and feel of concrete.
Westcoat designed ALX Pro for balconies, corridors and landings, and it is regularly specified for hotels, condominiums, apartments and office buildings. It is well suited to decks with spans of ten feet or more and to situations where extra crack resistance and flexibility are essential. On homes, the same system protects decks, balconies and covered porches.
The System, Layer by Layer
ALX Pro is installed in layers over plywood, and each layer has a specific job:
- Flashing. Sheet metal flashing at the wall-to-deck junction and the deck edge directs water off the deck and away from the structure.
- Sheet membrane. Westcoat requires sheet membrane on every plywood seam. For maximum protection, it can be applied across the entire deck.
- Lath. Reinforcing lath is stapled to the plywood to anchor the cementitious layers.
- Base coat. A polymer-modified cement base coat is troweled into the lath.
- Fiberlath-reinforced resin membrane. A reinforcing mesh embedded in waterproofing resin forms the waterproof layer of the system.
- Slurry coat. A smooth, uniform coat over the membrane.
- Texture coat. Sets the finished appearance and contributes to slip resistance.
- SC-10 acrylic topcoat. Two coats seal the system with a UV-resistant finish.
Why ALX Pro Is Waterproof
The waterproofing does not come from the topcoat alone. It comes from the way the layers work together. The fiberlath-reinforced resin membrane forms a continuous waterproof layer across the deck. Sheet membrane reinforces every plywood seam, where movement is most likely. Flashing at the walls and edges carries water off the deck, and a minimum slope of 1/4 inch per linear foot keeps it from collecting on the surface.
When sheet membrane is installed across the entire deck, Westcoat rates the system as a Class I vapor retarder under ASTM E96.
Fire Ratings and Code Compliance
According to Westcoat's specification, ALX Pro:
- Meets the Class A fire test (ASTM E-108)
- Meets a one-hour fire rating (ASTM E-119)
- Meets Wildland Urban Interface (WUI) requirements
- Is evaluated under IAPMO ER-587
For homes near wooded areas, or for decks attached to multi-story buildings, a fire-rated walking surface is a meaningful advantage.
Finish Options
The texture coat and topcoat allow a range of finishes, from a smooth concrete look to tile, slate, stone and paver patterns. Westcoat also offers slip-resistant additives for the topcoat, which it recommends for surfaces that may be exposed to wet conditions.
Over Plywood and Over Concrete
ALX Pro is designed for plywood. Westcoat calls for exterior-grade plywood at least 5/8 inch thick (3/4 inch preferred), joists spaced no more than 16 inches apart, and no OSB. The system can also be installed through most existing deck systems when the structure below is sound, which makes it a strong option for restoring problem decks.
We also apply the system over concrete, including entry steps, porches and patios. The concrete is prepared by diamond grinding or shot blasting before installation.
Manufacturer and Workmanship Warranties
360 Surfaces is a Westcoat Qualified Contractor Applicator (QCA). That status allows us to offer up to a 20-year Westcoat manufacturer warranty on ALX Pro installations. The warranty term depends on the system and the surface it is installed over. Every project also includes our own 5-year workmanship warranty.
Care and Maintenance
Routine care is simple: sweep the deck and rinse it with water. For grease or heavier dirt, Westcoat recommends a degreaser diluted 20:1 with water, a soft-bristle brush and a thorough rinse. Westcoat also recommends inspecting the system for wear every 2 to 4 years and resealing it every 3 to 5 years, depending on foot traffic and UV exposure.
Frequently Asked Questions
What is Westcoat ALX Pro?
ALX Pro is a bonded, waterproof walking deck system made by Westcoat. It combines a reinforcing lath, a fiberlath-reinforced resin membrane and a series of polymer-modified cementitious coats, sealed with an acrylic topcoat. It is designed for plywood decks, balconies, corridors and landings.
Is ALX Pro fire rated?
Yes. According to Westcoat's specification, ALX Pro meets the Class A fire test (ASTM E-108), meets the one-hour fire rating (ASTM E-119) and meets Wildland Urban Interface (WUI) requirements. It is evaluated under IAPMO ER-587.
How long is the warranty on an ALX Pro deck?
As a Westcoat Qualified Contractor Applicator, 360 Surfaces can offer up to a 20-year Westcoat manufacturer warranty, depending on the system and the surface it is installed over, plus our 5-year workmanship warranty.
How often does an ALX Pro deck need maintenance?
Westcoat recommends inspecting the system for wear every 2 to 4 years and resealing it every 3 to 5 years, depending on foot traffic and UV exposure. Routine care is sweeping and rinsing with water.
Request a Deck Coating Estimate in Vancouver WA and Portland OR
360 Surfaces installs Westcoat ALX Pro deck coatings and railing across Vancouver, Camas, Ridgefield, Battle Ground and the greater Portland metro. Call or text (360) 685-7222, email info@360surfaces.com, or request an estimate. To see the system, the warranty details and recent projects, visit our deck coating page.