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 Half Moon Bay
Duct sealing in Half Moon Bay typically runs $1,200 – $2,800 for a whole-home system, depending on access, duct material, and how far corrosion or moisture damage has spread. Most jobs take one to two days, with written pricing agreed before any work starts. Call (361) 326-5060 for a free estimate.
We serve Half Moon Bay from our San Francisco Bay Area dispatch office, with crews that know the difference between a 1960s ranch off Highway 1 and a newer build in Ocean Colony. The fog belt here isn’t a talking point, it’s a working condition. We’ve sealed ducts in El Granada where salt air had pinholed galvanized trunk lines, and in Miramar where flex runs in crawlspaces had turned into mildew farms because the original installer treated Half Moon Bay like Palo Alto. It isn’t. The humidity is different, the housing stock is different, and the failure modes are different. That’s why our Duct Sealing team carries mastic rated for marine environments, antimicrobial treatments for biological growth, and the patience to camera-inspect a system before quoting a price.
Why Hollis Air Duct Cleaning Is Half Moon Bay’s Preferred Duct Sealing Company
We’ve been in business since 2004 as part of the Garrison Partners family, and our Half Moon Bay customers come back because we write the price down before we touch anything. The 365-Day Done Right Promise means if a seal fails, a joint reopens, or the musty odor returns within a year, we come back and make it right at no charge, including a free second visit. No negotiation, no “let’s see what happened.”
Our technicians are background-checked and uniformed. You know who’s walking into your home before they arrive. Phones are answered by a live person 24 hours a day, 7 days a week. No voicemail loops, no callback queues, no waiting until Monday to schedule.
We know Half Moon Bay’s roads, its permit environment, and its houses. Crews arrive inside the quoted window, price in writing, complete the job by the book, and leave the site clean. That’s The Garrison Standard, and it’s how every independently owned Hollis location operates.
Duct Insulation in Half Moon Bay
Duct Insulation in Half Moon Bay is often the missing half of a sealing job. Sealing the leaks stops conditioned air from escaping, but in an unconditioned crawlspace or attic along the San Mateo County coast, the ducts still sit in cool, damp air that pulls heat out of the supply lines and puts it back in through the returns. Without insulation, you’re paying to recondition air you already paid to condition.
We see this most in the 1950s – 1970s ranch homes that dominate Half Moon Bay’s older neighborhoods. Original galvanized or early flex systems were rarely insulated to modern standards, and what wrapping exists has often absorbed decades of fog-belt moisture. When we open a crawlspace in El Granada and find the insulation jacket saturated and mold-stained, we know the homeowner has been breathing whatever’s growing in that blanket.
When Insulation Becomes Part of Sealing
We don’t sell insulation as an add-on. We recommend it when our camera inspection shows temperature drop across a run, or when the existing wrap is compromised. In Half Moon Bay’s climate, that compromise is almost guaranteed if the duct is in a vented crawlspace. We use professional-grade materials from Honeywell and Abatement Technologies, specified for damp coastal conditions, not the hardware-store wrap that delaminates in two seasons.
Vapor Control in Fog-Belt Crawlspaces
The real enemy here isn’t heat loss, it’s condensation. Warm supply air hits cool duct walls, moisture beads, and the “fog funk” smell that Half Moon Bay homeowners know too well starts circulating through the registers. Proper insulation with a sealed vapor barrier breaks that cycle. We price it as part of the system, not per linear foot, so you know the total before we start.
HVAC Duct Sealing in Half Moon Bay
HVAC Duct Sealing in Half Moon Bay means something different than it does twenty miles inland. Here, the job is as much about moisture and salt-air intrusion as it is about energy efficiency. A system that tests at acceptable static pressure can still be drawing corrosive, humid outdoor air through gaps in the return path, or leaking conditioned air into a crawlspace where it does nothing but feed mold colonies.
Our process starts with a negative-air setup using Nikro equipment to establish baseline pressure and identify leak points. We camera-inspect the trunk and branch lines, then seal with mastic and reinforcing mesh at joints, collars, and boot connections. Foil tape alone doesn’t survive Half Moon Bay’s humidity. We’ve pulled off “repairs” where tape had released within a season, reopening the leak and trapping moisture behind it.
Galvanized Systems and Coastal Corrosion
Many Half Moon Bay homes still run original galvanized steel ducts. The material is durable, but salt-laden air from El Granada and Miramar accelerates exterior corrosion that interior sealing can’t address. We inspect for pinholing and exterior degradation, and we’ll tell you honestly when sealing is a temporary patch versus a viable long-term solution. No point charging for a seal that reopens in eighteen months because the metal itself is failing.
Flex Duct Failures in Unconditioned Spaces
Flex duct pulled tight across crawlspaces degrades faster in damp conditions. The inner liner cracks, the insulation compacts, and the vapor barrier tears at support points. We replace failed sections with properly supported new flex, sealed with mastic at every connection, then insulate to current standards. The goal is a system that handles Half Moon Bay’s specific climate, not one that worked fine in a Sacramento test lab.
Trusted Brands We Service in Half Moon Bay
We stock parts and materials from Honeywell, Aprilaire, and Abatement Technologies for Half Moon Bay jobs, which means faster turnaround and no waiting for a Bay Area supplier to make a delivery run down Highway 1. Our rotary brush systems are from Rotobrush, our negative-air machines from Nikro. These are the same tools commercial crews use in hospitals and schools, and we maintain them to the same standard. When a Half Moon Bay homeowner needs a filtration upgrade after sealing, we can source Honeywell media cleaners or Aprilaire whole-house units without a two-week order delay. Equipment matters, but availability matters too, especially when you’re trying to solve a moisture problem before the next fog cycle rolls in.
Common Duct Sealing Problems We See in Half Moon Bay Homes
- Pinhole corrosion on galvanized runs near the coast. Salt-laden air from El Granada and Miramar eats the exterior of metal ducts while the interior looks fine. Homeowners seal the joints, but the pinholes reopen within a season or two because the corrosion continues from the outside in.
- Foil tape failure in damp crawlspaces. Standard adhesive tape releases when humidity stays above 70% for weeks at a time, which is normal in Half Moon Bay. The leak returns, often worse than before, because the failed tape traps moisture against the duct surface.
- Musty odor returning after “dry” sealing. A technician skips antimicrobial treatment because the duct looks dry at the moment of service. Fog-belt humidity returns, condensation forms at the new seal, and the “fog funk” smell comes back through registers even though pressure readings look correct.
- Outbuilding and detached garage systems neglected. Rural Half Moon Bay properties often have shop or barn HVAC tied to the main house ducting. These runs are longer, pass through unconditioned space, and leak more. They’re also rarely included in standard service quotes.
Pricing for Duct Sealing in Half Moon Bay, CA
A typical whole-home duct sealing in Half Moon Bay runs $1,200 – $2,800. Smaller systems or single-zone repairs start around $800. Outbuilding extensions, extensive corrosion replacement, or full insulation wrapping can push toward the upper end.
What moves the number: access (crawlspace height, attic hatch location), duct material (galvanized takes longer to prep and seal properly than flex), extent of moisture damage requiring antimicrobial treatment, and whether we’re also insulating after sealing. We do not price per vent or per linear foot. One flat price per system, written down before work starts, and it does not move at the door.
Every estimate is free. We’ll camera-inspect, pressure-test, and explain what we found before you decide. Call (361) 326-5060 to schedule.
We Also Serve Cities Near Half Moon Bay
Our crews regularly work in Half Moon Bay and the surrounding communities: El Granada, Burlingame, Millbrae, and Belmont. The coastal conditions vary, El Granada shares Half Moon Bay’s salt-air exposure, while Burlingame and Millbrae see more inland humidity patterns. We adjust materials and methods accordingly, not copy-paste the same approach.
Serving Half Moon Bay, CA - Our Local Coverage Area
We’re based in the Half Moon Bay 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 Half Moon Bay
Every three to four years for rural Half Moon Bay properties on unpaved roads, compared to the five-to-seven-year interval typical inland. Dust and pollen loading is heavier, wood heat introduces fine particulate that abrades flex duct interiors, and longer supply runs to outbuildings accumulate more debris. Call (361) 326-5060 and we’ll inspect to confirm your specific interval.
The cleaning removed the mold, but the moisture source, leaking joints drawing humid crawlspace air, wasn’t sealed. Half Moon Bay’s fog-belt humidity reseeds growth within weeks if the duct envelope isn’t closed. Sealing plus antimicrobial treatment is what stops the cycle. We can camera-inspect to confirm where the leaks are.
Yes, by reducing the negative pressure that pulls dust from wall cavities and crawlspaces into the return path. Wood heat itself is clean if the stove is properly vented, but the extra air movement in older ranch homes stirs up decades of accumulated debris. Sealing the duct envelope keeps that debris out of circulation.
Sealing stops air loss through existing holes, but it cannot stop exterior corrosion from continuing. For galvanized ducts in El Granada or Miramar, we assess whether the metal has enough integrity to hold a seal long-term. Sometimes partial replacement is the honest recommendation, and we’ll tell you that before quoting.
Yes, and they’re often the leakiest runs in a rural Half Moon Bay system. Longer flex lines, more joints, unconditioned space, and temperature swings cause expansion and contraction that opens connections. We include outbuilding systems in our whole-home assessment, or price them separately if you want to phase the work.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Half Moon Bay since 2004.