New garage floors
A garage floor is a slab with a few specific requirements: a smooth troweled finish that is easy to sweep, a slope toward the door so meltwater runs out, and a joint plan that suits the room. For an attached garage the floor is part of the house's permitted construction. For a new detached garage, Boise policy requires a frost-depth foundation once a building passes 400 square feet (or 600 square feet for light-frame construction), and Boise's frost depth is 24 inches. See concrete foundations and concrete slabs.
Winter salt and the garage floor
Idaho road crews use salt brine and magnesium chloride among other deicers. Whatever sticks to the car melts off on the garage floor, soaks into the surface and freezes again on cold nights if the garage is unheated. Over a few winters that can scale the top layer, especially near the door. A penetrating silane or siloxane sealer is the common cold-climate defense, and squeegeeing slush out after storms helps more than people expect.
Replace, resurface or coat?
| Problem | Usually |
|---|---|
| Hairline shrinkage cracks | Fill and seal, or coat |
| Surface scaling or pitting, slab sound | Resurfacing overlay, then seal or coat |
| A section sunk at a joint | Leveling or partial replacement |
| Heaved, broken, oil-soaked throughout | Tear-out and new floor |
Garage floor coatings (epoxy, polyaspartic, polyurea) are the most searched garage topic around Boise, but they are mostly installed by coating specialists rather than concrete contractors. A coating needs a sound, dry, prepared slab underneath. If the slab itself is failing, fix the concrete first; a coating will not hold a broken floor together. National guides put epoxy at about $3 to $7 per square foot.
What to tell a contractor
- Garage size, and whether it is attached or detached.
- Whether the floor has to come out first, and what's on it (cabinets, a water heater, a lift).
- Whether you want to coat it later, so the finish and curing suit a coating.
- Where the floor meets the driveway, since a new apron may be part of the job.
Back to the main guide: Boise concrete contractors.