Designed for heavy snow
NOAA's engineering weather data for Spokane lists a 50-year ground snow load of 42 pounds per square foot, and the design load for a deck comes from the local building code. Heavy snow on a deck, especially snow that slides off a roof and piles up, puts large loads on joists, beams, posts and footings. A deck in Spokane must be designed for the local snow load, with joist and beam sizes, post sizes and footings to match. A permit and inspection help confirm it.
Footings below the frost
A joint City of Spokane and Spokane County codes policy sets frost depth at 24 inches below finished grade unless a soils investigation supports a different depth. Deck footings should bear below the frost line. NOAA's data records about 72 freeze-thaw cycles in an average year; shallow footings heave and twist the frame.
Ledger flashing and moisture
Snowmelt runs down walls and finds its way behind poorly flashed ledgers, rotting both the ledger and the house framing. A properly flashed ledger, fastened with through-bolts or structural screws, is essential. Joist tape slows moisture damage under the boards.
Winter care
Use a plastic shovel on composite decks, avoid deicing salts that damage surfaces and corrode fasteners, and clear heavy snow from decks after big storms.
Railings and stairs
Icy stairs are a hazard. Build consistent risers, strong handrails and good lighting, and consider covered stairs.
Wildfire considerations
Homes near forested land should consider fire-resistant decking and keep the area under decks clear of debris.
Before you hire
Ask Spokane deck builders what snow load they'll design for, how deep footings will go, how they'll flash the ledger, and whether a permit is needed. Use L&I's contractor lookup to check their Washington registration, bond and insurance.
Composite or wood
Composite and PVC handle snow, ice and freeze-thaw without stain, and many homeowners in snowy climates prefer them for low maintenance. Wood costs less and is repairable but needs regular cleaning and refinishing. In either case, the frame and footings determine how long the deck lasts.
Covered decks and roofs
Covering part of a deck keeps snow off stairs and creates usable space in shoulder seasons. Any roof over a deck must be built for Spokane's snow load, with proper flashing where it meets the house.
Annual check
Each spring, after snowmelt, inspect the ledger, footings, posts, railings and stairs for movement, rot and loose or corroded fasteners. Clean the deck and clear debris from board gaps so water drains.
Lighting
Short winter days make good lighting on stairs and railings important. Plan low-voltage wiring before the decking goes down.
Hot tubs
A filled hot tub plus winter snow adds a heavy load. Design the frame and footings for both, or set the tub on its own slab.
Fasteners
Check fasteners and connectors each spring for corrosion and looseness after the winter.