Warmer floors on cold mornings
Crawl Space & Raised Floor Insulation in Santa Rosa, CA
Insulation under the floor, done right for a wet winter and a dry summer.
- Free on-site estimates
- Itemized written quote: material, thickness or depth, and R-value per area
- Air leaks, wiring and moisture checked before anything gets covered
Cold Floors Start Underneath
Crawl Space & Raised Floor Insulation matters in Santa Rosa because winter nights are colder than people expect. The city averages 30.2 mornings a year at freezing, and the coldest on record was 9°F in 1924. In a house on a raised foundation with nothing under the floor, the floor sits right above that cold, damp air, and drafts come up around pipes and wiring.
What we install
ENERGY STAR recommends R-19 for floors in zone 3, and OpenEI lists Sonoma County in zone 3C. For most raised floors that means batts held tight against the subfloor with proper supports, or closed-cell foam sprayed to the underside of the floor. Foam costs more but seals at the same time and does not sag or hold moisture, which helps in crawl spaces that stay damp through the rainy season.
Moisture first
Santa Rosa gets about 32 inches of rain a year, almost all of it from fall to spring. Before insulating, we check for standing water, wet soil, plumbing leaks and blocked vents. A ground vapor barrier over bare soil is often the first step. If water is coming in, that gets fixed before insulation goes in.
Crawl space walls
In a sealed crawl space, insulation goes on the walls instead of the floor. ENERGY STAR suggests R-5 sheathing or R-13 batts on crawl space walls in zone 3. This approach suits houses with ducts or plumbing in the crawl space.
Pests and debris
Rodents often get into old crawl space insulation. We remove fallen or soiled material before installing new.
Which houses have crawl spaces
Many older Santa Rosa, Petaluma, Sebastopol and Napa homes sit on raised wood floors over crawl spaces with vents in the foundation. Later subdivisions are a mix of raised floors and slabs. If you can see small vents along the bottom of your exterior walls, you probably have a crawl space we can insulate.
What This Covers
Floor and crawl space work we quote:
Underfloor batts
R-19 batts supported tight to the subfloor.
Underfloor spray foam
Closed-cell sprayed to the subfloor where damp air or limited access makes batts a poor fit.
Vapor barrier
Polyethylene over bare soil to cut ground moisture.
Crawl space wall insulation
Foam or rigid board on the walls of a sealed crawl space.
Rim joist sealing
Foam along the perimeter framing where outside air leaks in.
Old material removal
Fallen, wet or rodent-soiled insulation cleared out first.
Published Crawl Space Insulation Costs
| Job | Range and source |
|---|---|
| Crawl space, spray foam | $2,000 to $4,000 (HomeGuide); $1,000 to $5,900 (Fixr) |
| Closed-cell, installed | $3.00 to $5.00 per sq ft (HomeGuide) |
| Closed-cell on crawl space walls | $2 to $5 per sq ft (HomeGuide) |
| Crawl space vapor barrier | $1,200 to $4,000 (HomeGuide) |
| Crawl space encapsulation | $3 to $10 per sq ft, $3,000 to $15,000 (HomeGuide) |
| Crawl space vent sealing | $150 to $450 (HomeGuide) |
| Rim joists, spray foam | $2,000 to $2,500 (HomeGuide) |
From Fixr (2025) and HomeGuide's 2026 spray foam and crawl space guides. Floor area, clearance, moisture and any cleanup drive the cost. After we look under your house, the written estimate we give you is the price.
How It Works
1. Crawl space inspection
We check clearance, moisture, vents, plumbing, ducts and any old insulation.
2. Written quote
Floor or wall approach, material, R-value, vapor barrier and cleanup.
3. Clean and fix moisture
Old material removed; vapor barrier laid where needed.
4. Insulate
Batts supported or foam sprayed to the underside of the floor, with rim areas sealed.
5. Photos and walk through
We show you photos of the finished crawl space.
Crawl Space & Raised Floor Insulation Questions
What R-value goes under my floor?
ENERGY STAR recommends R-19 for floors in zone 3, which includes Sonoma County.
Should I seal my crawl space or keep it vented?
Most raised-floor houses here stay vented with insulation under the floor. Sealing and insulating the walls can make sense when ducts or plumbing run through the crawl space.
Can you insulate a very low crawl space?
Often, yes. Very tight spaces may be easier to do with foam than batts. We check clearance first.
Do I need a vapor barrier?
If the floor of the crawl space is bare soil, a vapor barrier usually helps keep moisture out of the insulation and framing.
Why do my floors feel cold even with a heater running?
Cold air moving through an open crawl space chills the subfloor, and gaps around pipes and wiring let that air into the room. Sealing those gaps and insulating under the floor usually fixes it.
Crawl Space & Raised Floor Insulation Service Areas
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Get a Crawl Space & Raised Floor Insulation Estimate
We go under the house and send a written price.