Whole-system duct and dryer vent check with before-and-after photos - you see exactly what came out of your vents
That "$99 whole-house special" is a bait ad - the real number appears once they are in your hallway, or the "clean" is a shop-vac at the register. We photograph the inside of your ducts before and after instead.
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AfterFast, Reliable Duct Sealing Across Redwood City
Most Redwood City homeowners call us after spotting dust streaks around ceiling vents or noticing one room never heats evenly. Duct sealing fixes the leaks that let conditioned air escape into your crawlspace or attic, and in Redwood City’s mix of 1950s ranch homes and downtown Victorians, it’s often the single most effective upgrade for both comfort and utility bills. Our crews dispatch from the San Francisco Bay Area office and carry mastic, mesh, and pressure-testing gear sized for the older ductwork we regularly find in neighborhoods from Redwood Village to Emerald Hills. If you’re seeing uneven airflow or your HVAC runs constantly, call (361) 326-5060 for a free inspection and written estimate.
Why Hollis Air Duct Cleaning Is Redwood City’s Preferred Duct Sealing Company
We’ve worked inside enough Redwood City homes to know the difference between a downtown Mount Carmel bungalow with original galvanized ducts and a Woodside Plaza Eichler with radiant heat and minimal duct runs. That local knowledge matters because the wrong approach wastes money. Our Duct Sealing in Redwood City crews follow The Garrison Standard: arrive inside the quoted window, price the job in writing before touching anything, and leave the site clean.
Roy Castellanos and the Hollis team have built our reputation on the 365-Day Done Right Promise. Every duct sealing job is covered in writing for a full year. If a seal fails or the pressure imbalance returns, we come back at no charge, including a free second visit. No negotiating, no runaround.
Our technicians are background-checked and uniformed. You’ll know who’s arriving before they knock. And when you call (361) 326-5060, a live person answers, 24 hours a day, 7 days a week. No voicemail loops, no callback queues.
Duct Sealing Services in Redwood City
Duct Sealing Services in Redwood City address the leaks, gaps, and disconnected joints that waste conditioned air and pull dust from crawlspaces and attics into your living space. The job starts with a pressure test or camera inspection to map the damage, followed by manual sealing with mastic and fiberglass mesh at every joint, register boot, and trunk connection. We then retest to confirm the system holds pressure. A typical whole-house duct sealing in Redwood City runs $1,200 – $2,800, depending on accessibility, duct material, and whether we’re working around original 1950s galvanized or newer flex runs.
Pressure Testing and Leak Mapping
We pressurize your duct system and measure airflow loss at the air handler. In Redwood Village and Roosevelt homes, we regularly find 25 – 40% leakage from unsealed original joints. The test gives us a baseline and lets us show you exactly where your money goes before we start.
Mastic Sealing at Joints and Registers
We brush on water-based duct mastic reinforced with mesh tape at every seam, boot, and penetration. Unlike foil tape, mastic stays flexible through decades of thermal expansion. It’s the standard our Rotobrush-trained crews apply on every job.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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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.
Duct Insulation in Redwood City
Duct Insulation in Redwood City wraps your sealed ducts with fiberglass or closed-cell insulation to prevent thermal loss as air travels through unconditioned spaces. In Redwood City’s climate, this matters more than on the flat Peninsula: west-side homes in Emerald Hills lose heat to cool marine air in crawlspaces, while east-side North Fair Oaks ducts bake in 90°F+ attics, forcing your HVAC to overwork. Insulation after sealing typically adds $800 – $1,500 to the project, depending on linear feet and whether we’re working in tight historic crawlspaces downtown.
Crawlspace and Attic Wrap
We use professional-grade insulation rated for moisture exposure in west-side applications and high-R-value batts for east-side attics. Every wrap is secured with mechanical fasteners, not tape that degrades.
Condensation Control in Marine Zones
Homes near Woodside Plaza and the western slopes see fog-driven condensation on cold duct surfaces. Proper insulation with a vapor barrier prevents the mold-friendly moisture that uninsulated sealed ducts can still harbor.
Trusted Brands We Service in Redwood City
Our vans stock sealing and filtration products from Aprilaire, Abatement Technologies, and Guardsman, plus rotary brush systems from Rotobrush for pre-seal cleaning. We don’t run to the supply house mid-job. For Redwood City homeowners, that means same-day completion on most sealing projects and parts that match your existing HVAC brand without compatibility guesswork. If your system uses Honeywell or Aprilaire filtration components, we integrate the seal job to protect those investments.
Common Duct Sealing Problems We See in Redwood City Homes
- Original 1950s Redwood Village and Roosevelt ductwork was installed with unsealed joints, so spring ground-shift after the dry season cracks old mastic and reopens leaks into the crawlspace. We find this pattern every March and April after the first heavy rains.
- Downtown and Mount Carmel vintage homes have undersized galvanized or retrofitted flex runs where sealing alone won’t fix pressure imbalance. The duct itself is too small for the air handler, and we flag this before quoting so you’re not paying for a partial fix.
- West-side Emerald Hills ducts carry fog-driven moisture that mold-feeds any unsealed seam, while east-side North Fair Oaks heat bakes dust into the same joints. A generic sealant spec misses one side of the city, so we adjust materials to the microclimate.
- Eichler-style homes in Woodside Plaza and Farm Hill often have minimal ductwork paired with radiant floor heating, but the small duct runs that do exist for ventilation or supplemental heat are frequently unsealed and uninsulated, leaking into the slab cavity.
Pricing for Duct Sealing in Redwood City, CA
A typical whole-house duct sealing in Redwood City runs $1,200 – $2,800. Duct insulation adds $800 – $1,500. What moves you within that range: accessibility (crawlspace height, attic hatch location), duct material (galvanized steel takes longer than flex), and whether we need to clean before sealing. Homes in the historic downtown district with tight basements or preservation restrictions may require additional labor for careful access.
We give one flat price per system, agreed in writing before work starts. No per-vent pricing, no add-ons at the door. Every estimate is free, and we show you the pressure-test results so you understand what you’re paying for. Call (361) 326-5060 to schedule.
We Also Serve Cities Near Redwood City
Our Duct Sealing crews regularly work in Atherton, Menlo Park, San Carlos, and Palo Alto. Each city has its own housing stock and climate patterns, but the same Garrison Standard applies: written price, background-checked technician, 365-Day Done Right Promise.
Serving Redwood City, CA - Our Local Coverage Area
We’re based in the Redwood City 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 About Duct Sealing in Redwood City
Redwood Village homes were built with unseamed galvanized ducts that leak at every joint by design, and decades of ground shift have opened gaps that modern flex duct doesn’t have. Newer homes in San Carlos or Menlo Park were sealed at construction. In Redwood Village, sealing is remediation, not maintenance. Call (361) 326-5060 for a pressure test to see your leakage percentage.
Yes. Redwood City’s strict green building codes often require duct sealing to be paired with energy upgrades or permits, unlike neighboring Peninsula cities. We document our work to code standards and can provide the pressure-test documentation your permit or rebate application requires. Ask us about this when you call for your estimate.
West-side homes in Emerald Hills and Woodside see fog-loaded marine air that feeds mold in unsealed joints, while east-side North Fair Oaks runs bake dust and lint onto duct interiors at 90°F+, so failing seams crack and whistle differently only a few miles apart. We inspect for moisture damage on the west side and thermal degradation on the east, then spec sealant and insulation accordingly. The same duct seal job is judged by two different failure clocks in this city.
Leaky return ducts in unconditioned crawlspaces create negative pressure that pulls lint, dust, and crawlspace debris into your HVAC airflow. In Redwood City’s older homes with combined laundry and utility rooms, this cross-contamination is common. Sealing the duct system isolates the air handler from these pollutants. We often find this during camera inspections in Roosevelt and Mount Carmel neighborhoods.
Most Eichlers rely on radiant floor heating and have minimal ductwork, but the small duct runs that exist for ventilation or supplemental heating are frequently unsealed and leak into the slab cavity or roof space. Sealing these short runs often delivers noticeable comfort improvement because the system has so little capacity to waste. We’ll inspect and tell you honestly whether sealing makes sense for your specific layout.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Redwood City since 2004.