Worked case: a three-car polyaspartic flake garage with cracks and a moisture primer in Bear Creek — what happens and what it costs

The scenario

Picture a three-car garage in a large home, about 32 by 22 feet, roughly 700 square feet. The slab has a handful of hairline cracks and two longer ones near the control joints. One bay has been used as a workshop, and a damp patch shows after the irrigation runs on the side yard. Two steps lead up to the house door. The doors face west, so the afternoon sun runs deep into the room.

The owners want one floor for three uses: cars, a workbench and a place to hose things down. They have heard that polyaspartic is quick and sun-tolerant. They also have a question about the damp patch, so the first step is a moisture test, not a color.

The starting conditions at a glance:

• Size: three-car garage, about 700 square feet
• Slab: sound but cracked in places, one damp patch, no old coating
• System: epoxy base with a polyaspartic top coat, over a moisture-vapor primer
• Setting: a gated community, west-facing doors and July and August mean highs near 91°F

What the job involves

1. The installer places calcium chloride kits or in-slab humidity probes, including one in the damp bay, and waits the time the test requires.
2. When the reading is above the limit of the chosen system, the plan adds a moisture-vapor barrier primer instead of coating over it.
3. A diamond grinder with a shroud and a vacuum opens the surface; the cracks are routed, filled and ground flush; the two steps get the same treatment with a hand grinder.
4. The primer goes down first; the pigmented epoxy base follows, with flake broadcast by hand until the base is covered.
5. The start is set for early morning, because a polyaspartic top coat has a short working time and a warm slab shortens it further; the installer checks the slab temperature and dew point before mixing.
6. The polyaspartic top coat is mixed in small batches and rolled quickly; the data sheet sets the day for foot traffic and the day the cars return.

Materials and prep

• Calcium chloride kits or drilled-hole humidity probes with their sleeves
• A walk-behind grinder fitted with diamond tooling and a vacuum, and a hand grinder for the two steps
• A moisture-vapor barrier primer, a tinted epoxy base, vinyl flake and a polyaspartic clear coat
• Squeegees, covers and a flake hopper, spiked shoes and fans for the open doors
• A surface thermometer and a dew point meter to pick the start

Add-ons often paired with this job

• Coat the stem wall (the low wall around the garage) — +$150–$400. The low curb at the doors can be wrapped in the same layers.
• Custom flake blend — +$100–$300. A blend chosen against the cabinets and the stucco is a small flat line.
• Move the garage contents out and back — +$150–$350. Emptying the workbench and shelves before the grind is a flat line an owner can take on.

Why it is done this way

The hybrid stack splits the work between layers. Epoxy bonds well to a ground slab and leaves time to broadcast the flake; a polyaspartic top coat is generally more UV-stable and cures faster, which fits a garage whose doors face the afternoon sun. That is the reason to pay $7–$11 per square foot instead of $6–$9.

The cracks add $1–$2 per square foot, which across 700 square feet is $700–$1,400 on top of the base. A crack is filled and ground flush; a moving crack can show again, and that is a conversation to have before signing, not after.

The moisture primer is a flat $400–$1,000. It is not a promise that the slab will stay dry; it is a layer many installers use when readings are high, and the alternative is waiting or reconsidering the job.

The heat shapes the day. A polyaspartic top coat can be installed in one day on a dry, workable slab, but vehicles return only after the time on the data sheet, often 24 hours to several days, so the cars park outside until then.

The alternatives that were weighed and set aside:

• Epoxy throughout at $6–$9 per square foot would cost less but can amber in sunlight at an open door.
• Waiting longer before coating costs nothing but time and is the right answer if the reading is far above the limit.

What would change the price

• A reading over the system's limit brings in the primer line of $400–$1,000, or a longer wait for the slab to dry.
• Beyond a handful of cracks, the crack line of $1–$2 per square foot grows or a flat extra-crack item appears.
• Two bays instead of three shrink the area to about 400 square feet, and each per-square-foot line shrinks with it.
• Coating late in a hot afternoon calls for smaller batches and an extra pair of hands on the top coat.
• The entry steps, a stem wall and clearing the room remain flat items.