Deck Installation in Mercer Island

The homes along East Mercer Way sit within feet of Lake Washington. Lake humidity stacked on Seattle's 37 inches of annual rain accelerates wood decay faster than most homeowners expect. Cedar decking on a 1960s split-level here can look rough in five years without proper ledger board flashing. That's why more Mercer Island owners are specifying TimberTech or Trex composite — and why the structural attachment to the rim joist matters as much as the surface choice. Composite doesn't rot. Cedar does.

Most of the housing stock in zip code 98040 was built between 1955 and 1980 — ranchers, split-levels, and mid-century contemporaries that step down the hillsides toward the waterfront. The North End along NE 24th Street and Island Crest Way tends to run slightly newer, 1970s–80s. The South End near SE 68th Street and the Roanoke Passage shoreline skews older — post-and-pier foundations, galvanized plumbing still common, original cedar siding on houses that haven't been touched since the Carter administration. Those rim joists are 50–60 years old. Before attaching any ledger board, we probe for rot, check the blocking, and sister any compromised framing. Lots near Luther Burbank Park on the northeast shore often feature post-and-pier foundations that need careful load calculations before adding a cantilevered deck above a slope. The same is true for waterfront parcels off West Mercer Way, where the grade drops sharply toward the East Channel. The downhill edge on a sloped Mercer Island lot can sit 10 feet off grade. That changes the structural conversation entirely — LVL beam sizing, post-to-beam connections, guardrail post embedment. None of it is off-the-shelf. Mercer Island runs its own building division out of City Hall on SE 36th Street — separate from King County DPER, which handles unincorporated parcels elsewhere in the county. Two different permit tracks, two different plan review timelines. The city's online portal has improved, but structural deck submittals still typically take 4–8 weeks to move through plan review. We handle the application and track it directly. The island's microclimate also matters. Sitting between the east and west channels of Lake Washington, north-facing surfaces accumulate moss faster than anywhere on the Eastside — composite decking with a ventilated substructure stays cleaner year to year compared to cedar, which needs stripping and sealing every 2–3 seasons just to hold its look.