Luxury Vinyl Plank in Mill Valley

Subfloor Prep

The City's Single-Family Residential Design Guidelines direct that buildings on sloped lots be designed to relate to existing landforms — 'for example, step with the slope' — and minimize earthwork cut, fill, and offhaul. Single-plane retaining or foundation walls visible from a public right-of-way are capped at six feet, with stepped retaining walls required above that height.

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 Mill Valley's Pre-1940, 1940s, 1950s, and 1960s stock than in anything recent. We confirm on site.

Over a crawlspace the plank is still waterproof, but "waterproof floor" is not "waterproof house" — moisture coming up through an open crawlspace ends up in the subfloor and the framing regardless of what's on top. We look underneath first. Where the subfloor has soft spots or movement, it gets fixed before anything floats over it.

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

Mill Valley Homes We Work In

ACS 2020-2024 5-year estimates show 28.2% of Mill Valley's 6,418 housing units predate 1940 — the oldest stock among the Marin markets covered here — with a further 11.5% built in the 1940s, 13.7% in the 1950s, and 16.6% in the 1960s. Roughly seven in ten units predate 1970. Mill Valley's Pre-1940, 1940s, 1950s, and 1960s homes are where LVP most often replaces carpet or sheet vinyl, and the subfloor under both is frequently uneven in ways nobody has seen for decades. The prep — not the plank — is the majority of the work in those houses, and it is the part that gets skipped by whoever installed the floor you're now replacing.