Spray Foam Insulation in San Francisco - Same-Day Service, Done Right the First Time

Fast, Reliable Spray Foam Insulation Across San Francisco

Spray foam insulation in San Francisco typically costs $3.50 to $7.00 per board foot for open-cell and $5.50 to $9.50 per board foot for closed-cell, with most whole-attic projects in the city landing between $4,200 and $9,800. You’ll have your exact written number before anyone picks up a tool. Thistledown Insulation San Francisco works in the Sunset, Richmond, Noe Valley, Bernal Heights, and every neighborhood between, with crews who understand that a 1920s Edwardian in the Outer Sunset behaves differently than a mid-century row house in the Mission. Call (341) 247-0222 and a live person answers, day or night, no voicemail tree.

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Why Thistledown Insulation San Francisco Is San Francisco’s Preferred Spray Foam Insulation Company

We’re an independently owned Cedarwell-family company, founded in 2003, and held to the Cedarwell Care Promise on every visit. That means shoe covers go on at the front door, drop cloths run down the hallway from the entry to the attic hatch, and you get a photo of the clean-up before our van pulls away. Our technicians are background-checked and uniformed, so you know exactly who’s walking upstairs while the baby naps.

We install Spray Foam Insulation using products from Icynene, Demilec, GreenFiber, and other trusted lines, matched to each home rather than whatever’s on the truck. San Francisco’s housing stock demands that level of care. A pre-1940 wood-frame Victorian with lath-and-plaster walls needs a different approach than a newer build near Glen Park. We walk you through the choice, write the number down, and stand behind it with our 365-Day Done Right Promise. If it’s not done right, we make it right. No debate, no fine print.

Our dispatch and scheduling are coordinated from the brand’s San Francisco Reflectix service office, with crews serving San Francisco locally. When you call, you get a person who knows the difference between fog-belt moisture in the Avenues and the drier air over Potrero Hill. That local knowledge shapes every recommendation we make.

Spray Foam Wall Insulation in San Francisco

Spray Foam Wall Insulation in San Francisco means working with homes where the walls are often uninsulated, the plaster is original, and the fog finds its way in by mid-afternoon. Spray foam wall insulation in San Francisco typically runs $3.50 to $7.00 per board foot depending on whether you choose open-cell or closed-cell product. For a typical 2-story wood-frame home with enclosed cavities, a full wall insulation project in San Francisco most often lands between $6,000 and $14,000. You’ll have your written price before we touch a rafter.

The job here is about air-sealing first. San Francisco’s persistent marine layer means the cold you feel inside isn’t just about missing insulation. It’s air moving through unsealed cavities, carrying damp salt air with it. We check for condensation inside wall cavities where the fog meets warm interior air, because sealing that moisture in behind lath and plaster is how hidden mold starts. This is the part generic insulation pages don’t tell you.

Vapor control for fog-belt walls

In the Sunset and Richmond districts, we pair spray foam with vapor control that accounts for the marine air pressing against the west-facing walls. Closed-cell foam can be a strong air and vapor barrier, but applied wrong on an old wood-frame wall, it traps condensation where you can’t see it. We assess each wall’s sheathing, age, and exposure before choosing the product. On a 1920s Edwardian with original shiplap, that often means open-cell foam with a smart vapor retarder, not just whatever sprays fastest.

Quiet, contained work in occupied homes

Wall insulation means working inside finished rooms, and that matters when there’s a toddler napping two doors down. We use quiet tools where possible, lay drop cloths across the hallway, and ask before we move anything. We choose pet-safe insulation products where a choice exists, so the dog can stay home during the job. Thistledown is the soft fluff of the thistle, one of nature’s lightest insulators. The name is a promise about how carefully we work.

Rim Joist Spray Foam in San Francisco

Rim Joist Spray Foam in San Francisco targets the band joist that runs around the perimeter of your basement or crawl space, a spot where cold marine air and fog-driven moisture sneak into pre-1940 foundations. Rim joist spray foam in San Francisco usually costs $2,800 to $5,600 for a typical single-family home, depending on linear footage, access, and the foam product you choose. Every quote is written down before work starts, and we never ask you to commit to a range.

In San Francisco’s older homes, the rim joist is often just a board with gaps around it, letting in the same damp air that chills your floors all afternoon. That’s not just uncomfortable. It pulls moisture into the framing, and over decades, that moisture feeds rot. Fog-driven air doesn’t stop at the foundation line. It finds the gaps.

Marine-air sealing for basements and crawl spaces

The unsealed rim joist in a pre-1940 basement is one of the most common failure points we see in San Francisco. Closed-cell foam works well here because it adds structural rigidity and acts as a vapor barrier, but only when the surrounding masonry and wood are dry enough to accept it. We inspect the sill plate and floor joists for signs of long-term moisture before we spray. If there’s active dampness, we talk to you about addressing it first, because foam over a wet rim joist just locks the problem in.

Protecting the wood, not just the heat

We pay attention to the condition of the existing wood, especially in homes within a few blocks of Ocean Beach or the Presidio, where salt-laden fog corrodes unprotected fasteners faster than anywhere inland. Where we find corroded anchors or soft wood, we flag it. You’ll hear about it from us, in writing, with a specific recommendation. That’s the Cedarwell Care Promise: never hiding a problem to keep a quote low.

Trusted Brands We Service in San Francisco

We install spray foam from Icynene, Demilec, and GreenFiber, along with other lines we’ve vetted over 20 years in the field. That range exists because a fog-belt Edwardian in the Outer Sunset and a 1950s bungalow in the Excelsior don’t need the same product. Icynene’s open-cell foam moves with an old house’s framing. Demilec’s closed-cell adds rigidity to a sagging rim joist. GreenFiber gives us a cellulose option where spray foam isn’t the right answer. Spray Foam Insulation in San Francisco should be a product match, not a brand pitch. We stock what San Francisco homes need and bring the right material to the job, not whatever’s left on the truck.

Common Spray Foam Insulation Problems We See in San Francisco Homes

• Condensation trapped behind lath and plaster. When the fog rolls through the Sunset, warm interior air meets cold wall cavities and water forms inside the wall. If spray foam is applied without vapor control, that moisture has nowhere to go.
• Salt-corroded fasteners and flashings. Ocean-facing neighborhoods see metal corrode years faster than inland. Unprotected fasteners near spray foam installations fail, letting air and water back in.
• Unsealed rim joists in pre-1940 basements. Fog-driven moisture and cold air bypass the best wall insulation through the band joist. We find this in almost every older home we inspect, from the Richmond to the Mission.
• Improperly applied closed-cell foam on old wood. Closed-cell is a great product in the right place, but sprayed over damp wood or without proper prep on an Edwardian wall, it can promote hidden mold instead of stopping it.

Pricing for Spray Foam Insulation in San Francisco, CA

We Also Serve Cities Near San Francisco

Our crews take care of homes in San Bruno, Albany, Piedmont, and El Cerrito as well. If you’re just outside San Francisco and dealing with the same fog, the same old wood-frame construction, and the same cold walls, give us a call at (341) 247-0222. We’ll send the same crew, the same written quote, and the same clean-up photo.

FAQs About Spray Foam Insulation in San Francisco