Fast, Reliable Blown-In Insulation Across Los Altos
Blown-in insulation in Los Altos typically runs $2.80-$4.50 per square foot for attic coverage, with most complete attic jobs landing between $3,200 and $6,800 depending on the home’s footprint and whether air sealing is needed first. Our crews serve Los Altos from our San Francisco Bay Area dispatch office, and we can usually schedule a blower-door assessment within 48 hours. Call (650) 381-1512 for a written price before any work starts.
Los Altos is not Mountain View. The cold-air drainage off the Santa Cruz Mountain foothills drops nighttime lows here 5-8°F below flatland Silicon Valley, and the pre-1975 ranch homes that dominate this city were built when California had no meaningful energy code. That combination means token attic insulation and bare wall cavities bleed heat through more hours of the year than the “mild Bay Area” reputation suggests. We’ve sealed and insulated over 9,000 homes since 2016, and the Los Altos jobs that deliver the clearest PG&E savings are the ones where we seal first, then insulate, in that exact order.
Why Topside Attic Insulation Union City Is Los Altos’s Preferred Blown-In Insulation Company
We don’t claim to be Los Altos natives. We claim to know what we find when we open up these homes. Our crews have worked the low-pitched ranches off Almond Avenue, the raised-foundation tracts near Grant Park, and the hillside homes along Magdalena Avenue where the cold-air drainage is most pronounced. Los Altos homeowners tend to read three-star reviews as carefully as five-star ones, and they ask for the blower-door numbers. We publish them.
Our response time to Los Altos is typically next-day or within 48 hours for standard assessments, and we answer calls live 24/7. Every job begins with a written price under Haven Standard Clause 1, and every job ends with a Documented Photo Record. We also offer a Free Second Opinion on any written estimate from another contractor. Bring us their scope; we’ll read it with you.
Our Blown-In Insulation Services in Los Altos

Blown-In Cellulose
Blown-in cellulose is our standard recommendation for Los Altos attics with shallow profiles and irregular framing. Made from recycled paper fiber treated with borate fire retardant, it packs into corners and around penetrations better than batts in the tight spaces common to 1950s and 1960s ranch construction. We source cellulose from GreenFiber and treat air sealing as a hard prerequisite, not an upsell. On a 1962 low-pitched ranch off Almond Avenue near downtown Los Altos, our crew opened a wall to run a new circuit and found bare studs with no cavity insulation at all - a standard 1960s California tract shortcut. The shallow attic profile ruled out batts, so we dense-packed the wall cavities with GreenFiber cellulose and blew Owens Corning fiberglass across the attic to a uniform depth, air-sealing the top plates and can lights first. The homeowner’s next PG&E cycle showed a clear drop in winter usage - the payoff came from sealing the leak paths before adding insulation, not from R-value alone.

Blown-In Fiberglass
Blown-in fiberglass from Owens Corning and CertainTeed works well in Los Altos attics where moisture management is a concern and where the homeowner wants a lighter material that won’t settle as aggressively over decades. We blow to a uniform depth, mark the joists so the coverage is verifiable, and we never blow over an unsealed attic floor. Wind-driven rain and cross-attic drafts through unsealed top plates and recessed-can penetrations in pre-1975 ranch attics push loose blown-in fiberglass sideways over time, leaving thin spots and thermal bypasses on the upwind side. We seal first.

Dense-Pack Wall Insulation
This is the service that separates Los Altos retrofits from generic Bay Area jobs. Technicians working pre-1975 Los Altos ranch homes frequently open walls to find bare studs with no insulation whatsoever - a standard California tract-building shortcut of the era. Dense-packing blows cellulose or fiberglass into closed wall cavities at high density, typically 3.0-3.5 pounds per cubic foot for cellulose, creating an air-impermeable blanket without removing drywall. Bare wall cavities in these 1950-1975 tract homes let dense-pack crews discover missing stud-bay coverage mid-job, so partial wall insulation often fails to deliver the expected bill savings until every cavity is packed. We scope every bay. We document what we find with photos.

Blown-In Top-Up
Many Los Altos ranches have existing blown-in fiberglass or cellulose that has settled below current code levels or was never deep enough to begin with. A blown-in top-up adds material to reach R-38 or R-49, but only after we assess what’s there and whether the attic floor has been sealed. We frequently find that “just add more” is the wrong prescription because the original insulation was installed over leaky top plates and can-light penetrations. The new layer won’t fix the bypasses. Our Blown-In Insulation team tests first, then specifies.

What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Before
AfterTrusted Brands We Service in Los Altos
We stock blown-in cellulose from GreenFiber, blown-in fiberglass from Owens Corning and CertainTeed, and spray foam from Icynene and Demilec. No proprietary lock-in means we specify the material that matches your home’s condition and your budget, not the product our supplier is pushing this quarter. For Los Altos retrofits, we keep GreenFiber cellulose and Owens Corning fiberglass on hand for fast turnaround, and we can source Johns Manville, Knauf, or Rockwool when a job calls for it. Every bag is documented in your written scope.
Common Blown-In Insulation Problems We See in Los Altos Homes

- Wind-driven redistribution of attic insulation. Cross-attic drafts through unsealed top plates and recessed-can penetrations in pre-1975 ranch attics push loose blown-in fiberglass sideways over time, leaving thin spots and thermal bypasses on the upwind side. We find these patterns repeatedly in the low-pitched ranches near downtown Los Altos.
- Bare wall cavities discovered mid-retrofit. The standard 1950-1975 California tract-building shortcut was to leave stud bays empty. Dense-pack crews on Los Altos jobs regularly open walls for electrical or plumbing access and find no insulation at all. Partial wall insulation fails to deliver expected savings until every cavity is packed.
- Moisture-wicked floor insulation in raised-foundation crawl spaces. Raised-foundation crawl spaces beneath the majority of Los Altos ranch homes vent moist outside air straight into the floor assembly. Without encapsulation first, blown-in floor insulation wicks moisture and settles, losing performance within a few seasons.
- Shallow attic profiles that rule out batt installation. The low-pitched roofs on Los Altos ranches often have less than 6 inches of clearance at the eaves. Blown-in material is the only practical way to achieve uniform coverage to the edges.
Pricing for Blown-In Insulation in Los Altos, CA
Most complete attic blown-in insulation jobs in Los Altos run between $3,200 and $6,800 for homes in the 1,400-2,400 square foot range. Dense-pack wall insulation adds $1,800-$3,400 depending on linear footage and whether we access through interior drywall or exterior siding. Blown-in top-up work, where existing material can be supplemented, typically falls between $1,400 and $2,800.
| Service | Typical Range in Los Altos |
|---|---|
| Blown-in attic insulation (complete, air-sealed) | $3,200 - $6,800 |
| Dense-pack wall insulation | $1,800 - $3,400 |
| Blown-in top-up to existing attic | $1,400 - $2,800 |
| Crawl space encapsulation + floor insulation | $2,600 - $5,200 |
What moves the number: attic square footage, current insulation depth and condition, accessibility, whether air sealing is needed first, and whether we discover bare wall cavities or other surprises once work begins. Every job gets a written price before any work starts - Haven Standard Clause 1 - and we include a Free Second Opinion if you have a competing estimate to compare. Call (650) 381-1512 for an exact quote; estimates are free.
We Also Serve Cities Near Los Altos

Our crews work throughout the Santa Clara Valley and San Francisco Peninsula. We regularly handle Blown-In Insulation in Los Altos and surrounding communities including Mountain View, Stanford, Palo Alto, and Menlo Park. Dispatch and scheduling are coordinated from our San Francisco Bay Area office; crews serve Los Altos locally.
Serving Los Altos, CA - Our Local Coverage Area
We’re based in the Los Altos area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Blown-In Insulation in Los Altos

Los Altos’s pre-1975 ranch housing stock was built with bare wall cavities as a standard tract-building shortcut, and the city’s colder nighttime temperatures from Santa Cruz foothill drainage mean those empty studs bleed heat for more hours per year than flatter, warmer Mountain View. Dense-pack wall insulation fills what the builder left empty. Call (650) 381-1512 and we’ll inspect a test bay with you before quoting.
Yes, and it’s often the only method that can. Blown-in cellulose or fiberglass is carried by hose to the eaves of low-pitched roofs where batts cannot be fitted or secured. We mark joist tops for depth verification and photograph the finished coverage for your Documented Photo Record. Shallow profiles are standard on Los Altos ranches; we’ve worked them hundreds of times.
Not necessarily before, but the crawl space should be evaluated in the same scope. Raised-foundation crawl spaces vent moist outside air into the floor assembly, and without encapsulation first, blown-in floor insulation wicks moisture and settles. The attic usually delivers faster payback because heat rises, but a complete envelope assessment - which we provide - lets you sequence the work by ROI. Call (650) 381-1512 for a blower-door test and written scope.
We specify GreenFiber cellulose, Owens Corning fiberglass, or CertainTeed fiberglass depending on your home’s moisture conditions, fire-safety requirements, and whether you have chemical sensitivities. The brand matters less than the installation quality - density, depth uniformity, and whether air sealing preceded the insulation. We document every bag lot in your written scope.
We open a test bay during the assessment, photograph what we find, and show you before quoting. On a 1962 ranch off Almond Avenue, our crew found exactly that - bare studs, no cavity insulation - and documented it before recommending dense-pack. You see what we see. No commitment required for the inspection.
Written by Wes Okafor, Owner at Topside Attic Insulation Union City, serving Los Altos since 2016.