Deck builders in Sammamish, WA

The median home in Sammamish was built around 1995. A deck built with a house of that age is now about 31 years old — the stage where first-generation pressure-treated decks commonly need major repair or replacement.

Decks built before 2004 were very likely made with CCA-treated lumber, which was phased out of most residential uses at the end of 2003. That doesn't make an existing deck unsafe, but old boards shouldn't be burned, and demolition debris should be disposed of according to local rules.

That makes Sammamish's housing 12 years newer than King County as a whole, where the median home was built in 1983. Statewide, the median Washington home was built in 1985. Among the 34 covered Washington communities with Census data, Sammamish ranks #28 for oldest housing. In these ZIP codes, 2% of homes were built before 1960, 14% between 1960 and 1979, 45% between 1980 and 1999, and 39% since 2000 — the single largest group dates to the 2000s.

The nearest NOAA climate station with 1991–2020 normals is Seattle Sand Pt Wsfo, about 11 miles away. It records an average of 25 days a year with a low at or below 32°F — relatively few freezing nights. On roughly 24 of those days the temperature climbs back above freezing, so water in wood, soil and gaps between boards repeatedly freezes and thaws.

Frost is less severe in Sammamish than in northern states, but footings still have to meet the local frost-depth requirement, and freeze-thaw cycles are enough to work loose nails and open checks in unsealed wood.

Snowfall is light — about 3.8 inches in an average year at Seattle Sand Pt Wsfo — so occasional ice is a bigger concern than snow load. Textured boards and good drainage on stairs help on icy mornings.

Sammamish sees about 37.8 inches of precipitation a year, with measurable rain or snow (0.1 inch or more) on about 95 days. Good drainage between boards, clean gaps and a ledger that is properly flashed keep that water from rotting the frame.

Summer heat is mild by comparison — average summer highs near 75°F and only about 2 days a year at 90°F or above — so board color can be chosen mostly on looks.

Budget, upkeep tolerance and sun exposure on your particular lot still decide the final choice between these options.

Sammamish has about 18,822 housing units across its covered ZIP codes. 85% are single-family detached homes, 4% are attached homes such as townhouses and rowhouses, and about 11% are in buildings with two or more units. Roughly 85% of occupied homes are owner-occupied.

Detached single-family homes dominate in Sammamish, so most decks are backyard decks attached to the rear of the house. That gives more freedom on size, layout and stairs, and makes a well-planned deck one of the most-used rooms of the home.

• Replacement and major repair: about 10,496 homes (56%) were built between 1970 and 1999, the age group whose original or early add-on decks are most likely to have worn-out framing, connectors and boards.
• Upgrades and expansions: about 2,835 homes (15%) were built since 2010. Their decks are usually sound but small or builder-grade, so enlarging the deck, adding stairs and switching to composite or upgraded railings are common.
• Retrofit decks on older homes: about 935 homes (5%) predate 1970. Here the priority is confirming that add-on decks are properly attached — or rebuilding them freestanding — before any cosmetic work.

Sammamish's milder winters — about 25 freezing nights a year — allow construction through most of the year. Spring and fall are still the busiest seasons, so booking early helps.

For Sammamish, WA, ask the permit office whether your deck needs a permit based on its size, height and attachment to the house, which drawings and inspections are required. Statewide code background for Washington is on our state page; local rules change, so the building department remains the authority.

The closest covered area is Issaquah, about 5.2 miles from the center of Sammamish's covered ZIPs. Its median home was built in 1997, 2 years later than in Sammamish. Sammamish has 38 percentage points more detached single-family homes (85% vs. 47%), which changes how many projects are backyard decks versus compact townhouse decks. Owner-occupancy is 85% in Sammamish compared with 65% in Issaquah. Sammamish's covered ZIP codes span about 20.1 square miles of land with roughly 18,822 homes — about 936 per square mile, a typical suburban density where most homes have usable backyards.