Worked case: a one-car garage floor in solid-color epoxy near the Village — what happens and what it costs

The scenario

Picture a one-car garage behind an older house a few blocks from the Village. The room measures about 12 by 20 feet, which is 240 square feet, and it holds two surfboards, a bike rack and a workbench. The slab is decades old, with a few hairline cracks near the door, a dark oil stain from a former car and a smooth, slightly chalky surface where an old sealer wore thin. The owner wants one clean color and a floor that sweeps easily.

The house sits close enough to the ocean that mornings are gray and humid through early summer. That matters more than the cracks. Damp air slows curing, and an older slab that has never had a vapor barrier under it can hold moisture that a coating will not forgive. The first question is therefore the moisture reading, not the color.

The starting conditions at a glance:

• Size: 12 by 20 feet, 240 square feet
• Slab: decades old, hairline cracks and spots of pitting, an oil stain, a worn sealer
• System: solid-color epoxy with fine grit in the top coat
• Climate: close to the ocean, gray damp mornings in late spring and early summer

What the job involves

1. The installer measures the room, checks the door and the threshold, and tapes a plastic sheet to the slab for a first look at moisture; a calcium chloride test or in-slab humidity probes follow if the sheet shows condensation.
2. A diamond grinder with a dust shroud and a vacuum cuts the old sealer and the oil-affected surface away and opens the slab to a profile the coating can grip; the garage door stays open for ventilation.
3. Hairline cracks are routed slightly, filled with a flexible repair material and ground flush, and the pitted spots are patched and sanded smooth.
4. The oil stain is degreased and ground again; where it keeps rising through the surface, the installer adds a spot of primer before the base coat.
5. A primer goes on, followed by a pigmented 100%-solids epoxy coat in one even color, rolled in sections with spiked shoes on the wet film.
6. A clear top coat with fine grit is rolled over the color for texture, and the cure time on the data sheet sets the date for foot traffic and for parking.

Materials and prep

• Diamond grinder with a dust shroud and a vacuum
• Flexible crack filler and a small patch mortar
• Moisture test supplies: plastic sheet, calcium chloride kit or humidity probes
• Epoxy primer, pigmented 100%-solids epoxy and a clear top coat with fine grit
• Rollers, squeegee, spiked shoes and masking tape

Add-ons often paired with this job

• Coat the entry steps or landing — +$100–$300. An entry step from the house into the garage is coated in the same color, as a flat add-on, so the edge matches the floor.
• Extra crack or joint repair (many cracks) — +$150–$450. If the cracks are more than a few hairlines, a separate crack and joint line covers the extra repair.
• Move the garage contents out and back — +$150–$400. Moving the bikes and the surfboards out and back is a flat line the owner can take on.

Why it is done this way

Solid color works here because the budget is small and the room is a workshop. It also demands the most from the prep. A single smooth color shows every pit, patch and trowel mark, so the repairs are ground flush before the first coat goes down.

The moisture check comes first because the garage is close to the water. A slab near the coast can hold moisture that rises through a coating over time. A plastic-sheet check is a first look, and a number from a calcium chloride test or in-slab probes decides whether a vapor-barrier primer is needed.

Grit in the top coat is a trade-off, not a safety promise. No floor is non-slip, and a coated floor can be slippery when wet or oily. A fine grit adds texture, and the owner chooses how much against how easy the floor is to sweep.

The alternatives that were weighed and set aside:

• Flake would hide the pits better and cost $5–$8 per square foot instead of $3–$6, a reasonable upgrade for a visible garage.
• A DIY kit would save money on materials and ask the owner for a rented grinder, a damp-slab decision and a long day; the solid-color page compares the two.

What would change the price

• A moisture reading above the primer threshold adds the damp-slab line of $2–$4 per square foot.
• A larger crack that moves rather than a hairline needs a flexible repair and may show through the coating.
• A garage that is 14 by 24 feet instead of 12 by 20 changes the area to 336 square feet, and every line scales with it.
• Stepping up to flake adds material and a second pass.
• Entry steps and the stem wall are flat add-ons.