Fast, Reliable Blown-In Insulation Across Los Altos Hills
Blown-in insulation in Los Altos Hills typically costs $2.80-$5.40 per square foot installed, with most custom homes running $4,200-$12,000 depending on cavity access and whether air sealing is included. Our crews are dispatched from the San Francisco Bay Area office and can usually be on-site in Los Altos Hills within 24-48 hours of your call. We don’t do flat-attic blow-ins and call it done - every job starts with a blower-door test to measure what you’re actually losing, then we seal, then we insulate. Call (831) 534-3206 for a written price before any work starts.
Why Topside Attic Insulation Campbell Is Los Altos Hills’s Preferred Blown-In Insulation Company
We’ve worked on enough Los Altos Hills homes to know that no two are alike. The 1-acre minimum lot size here has produced a city of custom builds - post-and-beam mid-century moderns, hillside ranch homes with pier-and-grade-beam foundations, and contemporary estates with vaulted cathedral ceilings that were never designed with insulation cavities in mind. That means every blown-in insulation job in Los Altos Hills requires a site-specific scope, not a standard attic package.
Our local reputation is built on documented results. Every applicable job finishes with before-and-after blower-door numbers - a pressurization reading that shows, in one figure, how much conditioned air your home was losing before and after the work. Homeowners in Los Altos Hills receive a written scope, a written warranty, and a Documented Photo Record before the crew leaves. Under the Haven Standard, your price is flat and fixed before anyone lifts a tool.
Calls are answered by a live person 24/7. No voicemail loops, no callback windows measured in business days. If you have a written estimate from another contractor, we’ll read it with you - free second opinion, no obligation.
Our Blown-In Insulation Services in Los Altos Hills

Blown-In Cellulose
We use blown-in cellulose for Los Altos Hills wall cavities and accessible attics where we can achieve the full settled density the material requires. Cellulose handles the foothill temperature swings well - it’s treated with borate fire retardant and performs consistently through the 6-10°F overnight drops that Los Altos Hills experiences below valley-floor temperatures. On sloped-lot homes near Moody Road or along the Permanente Creek drainage, we pair cellulose with targeted air sealing of top plates and penetrations so the insulation doesn’t become a filter for the air leaks underneath.

Blown-In Fiberglass
Blown-in fiberglass works for standard attic floors in Los Altos Hills homes that have them, though frankly many of the 1950s-1970s custom builds in this city don’t. Where we do use fiberglass, we specify higher-density loose-fill or stabilized product to resist the settlement that occurs when contractors blow at minimum thickness. We source from Owens Corning and Knauf - no proprietary lock-in, so you know exactly what product is going in your walls.

Dense-Pack Wall Insulation
This is where blown-in insulation in Los Altos Hills gets technically demanding. Dense-pack cellulose or fiberglass is blown into closed wall cavities at 3.5-4.0 lbs per cubic foot, creating an air-impermeable insulation blanket that also reduces convection looping. For the post-and-beam and platform-framed custom homes throughout Los Altos Hills - many with no exterior sheathing air barrier - dense-pack is often the only practical retrofit path without gutting interior drywall. We verify density with wall-cavity fill monitoring so you don’t get the settling voids that plague standard loose-fill retrofits.

Blown-In Top-Up
Some Los Altos Hills homes have existing insulation that’s simply underweight for the thermal load. A blown-in top-up adds R-value without full removal, but only after we test what’s there. We’ve found compressed or moisture-damaged fiberglass in hillside crawl spaces off La Barranca Road and Black Mountain Road where fog-damp air had been migrating through unsealed rim joists. We document the condition, seal the leaks, then top up with compatible material to the depth your roof assembly or floor cavity can actually accommodate.

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.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Before
AfterTrusted Brands We Service in Los Altos Hills
We stock and install blown-in insulation from Rockwool, CertainTeed, and Icynene for Los Altos Hills jobs, with materials ordered to spec rather than pushed from inventory. Rockwool’s mineral wool loose-fill handles the fire-safety requirements that Santa Clara County enforces in wildland-urban interface zones. CertainTeed’s fiberglass systems work for standard attic top-ups where cavity geometry allows. Icynene’s open-cell spray foam pairs with blown-in approaches in hybrid assemblies - common on the low-slope roof decks we see throughout Los Altos Hills’s mid-century stock. We don’t represent any manufacturer exclusively, so the product choice follows your home’s needs, not our supplier incentives.
Common Blown-In Insulation Problems We See in Los Altos Hills Homes

- Vaulted ceiling blow-ins with no cavity. Contractors install standard loose-fill blown-in insulation at flat-attic thickness over vaulted cathedral ceilings that were never built with a cavity. The material spills into the vault space, delivers almost no R-value, and often blocks ventilation paths. We see this repeatedly in 1960s-1970s custom homes near Foothill College and along the upper reaches of Elena Road.
- Fog-damaged crawl-space insulation without vapor retarders. Marine fog pools in Los Altos Hills’s foothill canyons overnight, elevating crawl-space relative humidity. Blown-in fiberglass or cellulose installed without a proper vapor retarder compresses or sours within a season or two. On hillside cuts along Moody Road and Black Mountain Road, we specify sealed crawl-space encapsulation or rigid-board insulation with taped seams before any blown-in material goes in.
- Low-slope roof decks treated like gable attics. A significant share of Los Altos Hills’s mid-century custom homes have flat or very low-slope built-up roofs with no accessible attic cavity. The only code-compliant retrofit path is a closed-cell spray foam or rigid-insulation roof-deck overlay with Title 24 cool-roof compliance - a scope almost never required in neighboring Los Altos or Mountain View. Contractors who skip this step trigger thermal bridging through post-and-beam framing and potential county non-compliance.
- ADU insulation mismatched to main-house deficiencies. State-mandated ADU construction is adding conditioned space to Los Altos Hills properties where the main house itself is under-insulated. Blown-in top-ups on the original structure get deferred while the new unit gets full treatment, leaving the homeowner with two thermal zones that perform nothing alike. We scope ADU and main-house work together so the building envelope functions as one system.
Pricing for Blown-In Insulation in Los Altos Hills, CA
Most blown-in insulation jobs in Los Altos Hills fall in these ranges:
- Blown-in cellulose attic floor (standard cavity): $2.80-$4.20/sq ft
- Dense-pack wall insulation (retrofit, closed cavity): $4.50-$6.80/sq ft
- Blown-in fiberglass top-up over existing: $2.20-$3.60/sq ft
- Low-slope roof deck rigid board + closed-cell overlay: $8.50-$14.00/sq ft
- Crawl-space encapsulation + insulation (sloped hillside): $6,500-$14,000 total
What moves you within these ranges: cavity accessibility (vaulted ceilings require interior access or roof-deck work), existing insulation condition, air-sealing scope, and whether blower-door verification is included. We don’t quote by phone without seeing the home - but we do provide a written, flat price on-site before any work starts, under Haven Standard Clause 1. No estimates that balloon into invoices. Call (831) 534-3206 to schedule a free assessment.
We Also Serve Cities Near Los Altos Hills

Our Blown-In Insulation crews work throughout the South Bay, including Campbell, Los Gatos, Saratoga, and Cupertino. If you’re outside Los Altos Hills city limits but in the foothill zone with similar custom-home stock - vaulted ceilings, sloped lots, post-and-beam framing - the same technical scope applies. We coordinate dispatch from our San Francisco Bay Area office and route crews by job type, not just geography, so the technician who arrives understands your home’s construction era.
Serving Los Altos Hills, CA - Our Local Coverage Area
We’re based in the Los Altos Hills 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 Hills

Vaulted cathedral ceilings in Los Altos Hills homes were often built with no insulation cavity at all - the roof deck sits directly on or very near the ceiling finish. Standard blown-in loose fill requires a cavity to fill; without one, the material simply accumulates at the vault’s low point and delivers negligible R-value. We address these assemblies with dense-pack wall methods where interior access exists, or with rigid-board and closed-cell spray foam roof-deck overlays where the ceiling plane is fixed. Call (831) 534-3206 and we’ll specify the path that matches your roof structure.
No, and any contractor who says they can is installing material that won’t perform. Low-slope built-up roofs with no cavity require a roof-deck overlay approach: rigid insulation boards, closed-cell spray foam, or a hybrid assembly, finished to Santa Clara County Title 24 cool-roof standards. This is specialized work we perform regularly in Los Altos Hills’s mid-century custom home stock. We’ll inspect the deck condition, specify the overlay system, and give you a written price before any work starts.
Los Altos Hills sits 200-800 feet in the Santa Cruz Mountain foothills, and that elevation generates cold-air drainage that pushes overnight lows 6-10°F below Palo Alto or Mountain View. Under-insulated floors and crawl spaces become uncomfortably apparent in ways flatland Bay Area residents don’t expect. We specify higher R-values for floor assemblies in Los Altos Hills, and we never install blown-in material without first sealing the air leaks that let that cold air migrate through the building envelope. The blower-door test quantifies the difference.
Yes, and we recommend scoping the main house simultaneously. Los Altos Hills’s ADU boom is adding conditioned space to properties where the original custom home is already under-insulated. Blown-in top-ups or dense-pack wall work on the main structure, paired with full insulation in the new unit, prevents the two zones from performing like separate buildings. We coordinate with your ADU contractor or handle the insulation scope independently - either way, you get one written price and one documented record for the full property.
We use Owens Corning and Knauf fiberglass systems where cavity geometry and moisture conditions allow; GreenFiber cellulose is available for homeowners who prefer a recycled-content product with borate fire retardant. We don’t lock you into any single brand. The product selection follows your home’s specific conditions - fog exposure, wildland-urban interface requirements, cavity depth - and we document exactly what goes in before installation begins. Call (831) 534-3206 to review material options for your job.
Written by Wes Okafor, Owner at Topside Attic Insulation Campbell, serving Los Altos Hills since 2016.