Engineered Hardwood in Larkspur

What Larkspur's Humidity Asks of Engineered Hardwood

In Larkspur the case for engineered hardwood rests more on plank width and slab than on climate, and the measurements show why. Hourly dewpoint readings from Gnoss Field, Novato, 14 miles away, put that air at a median 40.1% relative humidity once it is heated to 70°F over winter — 15% of those hours under NWFA's 30% minimum — rising to 56% in summer. A solid 5-inch white oak board living through that, at roughly 7.7% to 10.3% equilibrium moisture content, changes width by about 0.049 inch between seasons. A cross-laminated core exists to restrain that movement; how much it restrains depends on the product's construction, so we go by the manufacturer's stated humidity range for the specific floor rather than a general rule.

Source: Hourly ASOS dewpoint observations 2015–2025, Iowa Environmental Mesonet (Iowa State University); equilibrium moisture content from USDA Wood Handbook FPL-GTR-190 Eq. 4-5; movement from FPL-GTR-282 Eq. 13-3 and Table 13-5

Subfloor and Foundation Work

The City's Planning Department lists slope use permits among the development applications it processes.

Regionally, crawl space use in Pacific-division construction has declined long-term and dropped sharply only in the past decade, against 89.9% slab in new 2024 builds — so raised floors turn up more often in Larkspur's 1950s, 1960s, and 1970s stock than in anything recent. We confirm on site.

Over a crawlspace, engineered goes down by nail, staple, glue, or float, so the method follows the subfloor rather than the other way round. We flatten the subfloor first — engineered plank is stiff, and it bridges dips instead of following them, which is what produces hollow spots underfoot.

Source: NAHB analysis of the Census Bureau Survey of Construction, foundation type by region (2024)

Larkspur Homes We Work In

Larkspur sits at about 10 feet in Marin County. ACS 2020-2024 5-year estimates put 59.4% of Larkspur's 6,431 housing units in the 1950-1979 range: 23.2% from the 1970s, 23.1% from the 1960s and 13.1% from the 1950s, with a further 9.6% predating 1940. In Larkspur's 1950s, 1960s, and 1970s housing, engineered often wins on height as much as on moisture: a thinner assembly clears existing door jambs, appliance toe-kicks, and the transitions to rooms that aren't being redone, which matters when only part of the house is getting new floor.