Coating floors in Spokane
Spokane's winters are long and snowy, and a garage floor here spends months taking wet tires, slush and road treatment. NOAA's engineering weather data for Spokane lists a 50-year ground snow load of 42 pounds per square foot and an average of about 72 freeze-thaw cycles a year. That combination makes winter durability, and winter installation, the main things to plan for.
Deicer comes home on the tires
The City of Spokane puts down a lot of material in a snow event: during one December 2021 storm, crews used 544 tons of granular deicer, sand and salt and 173,709 gallons of liquid deicer. Whatever is on the roads ends up in the garage. Deicer residue can dull a coating and leave a slippery film, sand acts as an abrasive, and salty meltwater sitting on bare concrete through repeated freezing and thawing can scale the surface. A well-bonded coating with a durable, chemical-resistant topcoat protects the slab; texture keeps a wet floor from getting slick. Plan on a walk-off area at the door and rinsing the floor during the winter.
Repair before coating
Many Spokane garage slabs already show scaling or spalling near the door. That damage has to be ground back to sound concrete and repaired before coating, or the coating will fail where the concrete underneath is weak. Ask the specialist how they'll assess and repair damaged areas, and get it in the proposal.
Cold slabs and cure times
Cold slows the cure of most coatings, and every product has minimum slab and air temperatures on its data sheet. A garage slab can be much colder than the air through most of the winter. If work is done in the cold months, ask whether the crew will heat the space and the slab, which products tolerate cold, and how long the floor will need before you can park on it, since cold can stretch cure times well beyond the warm-weather numbers. Many owners schedule garage work for late spring through early fall.
Moisture
A joint City of Spokane and Spokane County policy sets frost depth at 24 inches below finished grade for footings, a reminder of how deep cold reaches in the ground here. Snowmelt and spring thaw also put a lot of water against foundations and slabs. Test the slab before coating, with ASTM F1869 or ASTM F2170, and use a moisture-mitigating primer if the results are higher than the coating tolerates.
Studded tires
Studded tires are legal in Washington for part of the year, and studs are hard on coatings, especially thin ones. If someone in the household drives on studs, mention it: the specialist may recommend a thicker system or a harder topcoat in the parking area.
Checking a contractor in Washington
Washington's Department of Labor & Industries publishes a free contractor registration lookup. Check the business's registration, and the bond and insurance information L&I lists, before you sign.