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.
Before
After
Before
After
Before
AfterFast, Reliable Duct Sealing Across La Crescenta-Montrose
Duct sealing in La Crescenta-Montrose typically costs $400 – $1,200 for a whole-house seal on mid-century homes, with most jobs completed in a single visit. Our crews serve La Crescenta-Montrose from the Los Angeles office, carrying mastic, mesh, and insulation wrap sized for the galvanized trunks and flex runs common in this area. If your registers blow gray dust after every Santa Ana wind, the problem is usually leaky ductwork, not dirty ducts. Call (361) 326-5060 for a free estimate with a written price before any work starts.
We’ve worked on enough houses off Rosemont Avenue, in the neighborhoods below the Verdugo Mountains, and along Foothill Boulevard to know what La Crescenta-Montrose duct systems look like after sixty or seventy years. Shallow attics. Original galvanized trunks. Staged re-ducting that left mismatched connections. Our technicians show up uniformed, background-checked, and equipped with Rotobrush rotary systems and Nikro negative-air machines. The price we write down is the price you pay. That’s The Garrison Standard.
Why Hollis Air Duct Cleaning Is La Crescenta-Montrose’s Preferred Duct Sealing Company
Hollis Air Duct Cleaning has been part of the Garrison Partners family since 2004. In La Crescenta-Montrose, that longevity matters because the duct problems here aren’t generic. They’re specific to mid-century housing stock, high-wind corridors, and post-fire ash intrusion that most out-of-area crews don’t recognize until they’re halfway through a job.
Our La Crescenta-Montrose customers get the 365-Day Done Right Promise on every seal: if the work fails within a year, we return and make it right at no charge, including a free second visit. No negotiation, no runaround. We also price in writing before touching anything. No estimates that balloon once the technician is inside your home.
Phones are answered by a live person 24 hours a day, 7 days a week. Scheduling is coordinated from our Los Angeles office, with local crews dispatched to La Crescenta-Montrose inside the quoted window. You know who’s arriving before they walk in. Background-checked, uniformed, accountable.
Duct Sealing Services in La Crescenta-Montrose
Duct Sealing Services in La Crescenta-Montrose address the leaks, gaps, and disconnected joints that let unfiltered air bypass your HVAC system entirely. In this city, sealing is often the real fix after a cleaning because decades of thermal cycling in shallow attics have opened pinholes in galvanized trunks and crushed flex connections at the plenum. A typical whole-house duct seal in La Crescenta-Montrose runs $400 – $1,200 depending on system size and accessibility, with partial seals on isolated problem zones starting around $250.
Leak Detection and Mastic Sealing
We pressurize the duct system and use smoke pencils or thermal cameras to find every leak, then seal with water-based mastic and fiberglass mesh. Mastic stays flexible for years, unlike tape that dries and peels. In La Crescenta-Montrose’s dry climate, that flexibility matters. The seal has to survive summer attic heat above 140°F and winter nights near freezing.
Reconnection of Disconnected Runs
On older homes, we regularly find flex runs that have pulled completely free of the trunk line or register boot. We reconnect with proper mechanical fasteners, seal the joint, and support the flex so it doesn’t sag or crush again. A disconnected bedroom run in a 1950s ranch is why that room never heats evenly.
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.
Duct Insulation in La Crescenta-Montrose
Duct Insulation in La Crescenta-Montrose replaces the degraded wrap that crumbles off bare metal in shallow, hot attics. Once insulation falls away, the metal sweats in summer, rusts at seams, and loses thermal efficiency. In a city where summer AC runs hard and Santa Ana winds drive attic temperatures even higher, bare ductwork is both an energy drain and a moisture problem. Duct insulation replacement in La Crescenta-Montrose typically runs $600 – $1,800 for a full system, often bundled with sealing work.
Attic Wrap Replacement
We remove degraded fiberglass or foil-backed wrap and install new insulation rated for the temperature swings in La Crescenta-Montrose attics. Proper wrap keeps conditioned air at temperature from the air handler to the register. Without it, you’re paying to cool air that warms fifteen degrees before it reaches your bedroom.
Vapor Barrier Repair
Where old insulation has absorbed moisture from attic condensation, the vapor barrier is usually compromised. We address the source, replace the wet material, and restore the barrier so the new wrap doesn’t fail the same way. This is common in the shallow attics along the Verdugo foothills where ventilation is limited.
Trusted Brands We Service in La Crescenta-Montrose
Our La Crescenta-Montrose crews carry sealing and insulation products from Abatement Technologies, Aprilaire, and Guardsman, the same filtration and ductwork brands used in commercial installations across Los Angeles County. We stock mastic, mesh, and replacement wrap locally, so most La Crescenta-Montrose jobs don’t wait on parts. If your system uses Honeywell or Aprilaire filtration components, we can assess how those filters interact with your duct sealing and recommend the right MERV rating for the ash and pollen load in this area.
Common Duct Sealing Problems We See in La Crescenta-Montrose Homes
- Pinhole leaks in original galvanized trunks. The 1940s – 1960s metal ductwork in La Crescenta-Montrose homes has undergone decades of expansion and contraction. Tiny holes open at seams and joints, creating negative-pressure entry points for ash and dust during wind events.
- Crushed or unsealed flex connections. Staged re-ducting left many homes with mismatched systems. New flex run connects to old metal with a zip tie and hope. Those connections leak pressure and pull attic air straight into the supply.
- Disconnected runs in shallow attics. Crawl space is tight, work is awkward, and old supports fail. We’ve found entire bedroom feeds lying open in the attic, blowing conditioned air into insulation instead of the room below.
- Rust at uninsulated seams. Where wrap has fallen away, summer condensation meets bare metal. Rust eats the seal. In La Crescenta-Montrose’s dry climate, this happens faster than homeowners expect because attic temperature swings are extreme.
Pricing for Duct Sealing in La Crescenta-Montrose, CA
A typical duct sealing job in La Crescenta-Montrose runs $400 – $1,200 for a whole-house seal, with smaller partial repairs starting at $250. Duct insulation replacement adds $600 – $1,800 depending on linear footage and attic accessibility. These ranges reflect the mid-century housing stock here: shallow attics, mixed materials, and the extra labor of working around original construction.
What moves the price: system size, number of disconnected runs, condition of existing insulation, and whether we need to remove degraded material before sealing. We inspect first, write the price down, and get your approval before any work starts. No per-vent pricing, no teaser coupons that triple at the door. One flat price per system, agreed in advance. Estimates are free. Call (361) 326-5060.
We Also Serve Cities Near La Crescenta-Montrose
Hollis Air Duct Cleaning dispatches crews throughout Southern and Northern California, including La Crescenta-Montrose, Los Angeles, San Diego, San Jose, and San Francisco. Each location operates independently under The Garrison Standard. Whether you need Duct Sealing in the Bay Area or ductwork repair in San Diego, the same written-price, written-guarantee discipline applies.
Serving La Crescenta-Montrose, CA - Our Local Coverage Area
We’re based in the La Crescenta-Montrose 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 La Crescenta-Montrose
It’s usually both, but sealing is the permanent fix. Cleaning removes the ash already inside; sealing stops new ash from entering through leaks in your return and supply ducts. In La Crescenta-Montrose, negative pressure from leaky ductwork pulls fine particulate straight past your filter during wind events. We assess with a camera inspection, clean what has accumulated, then seal the entry points with mastic and mesh. Call (361) 326-5060 for an exact quote; estimates are free.
Most original galvanized trunks can be sealed if the metal is structurally sound. We inspect with a camera scope to check for rust-through, disconnected joints, or crushed sections. On a 1952 ranch house off Rosemont Avenue, our tech found two disconnected runs and crushed flex feeding rear bedrooms. We cleaned, sealed with mastic and mesh, and wrapped the insulation. The homeowner reported the back rooms finally stopped smelling like smoke after the next Verdugo wind event. If the metal is too far gone, we’ll tell you and quote replacement. Call (361) 326-5060 for a camera inspection.
Yes. We follow NADCA assessment protocols and use Nikro negative-air machines with HEPA filtration during any cleaning that precedes sealing. Negative pressure captures dislodged debris before it enters your living space, critical in La Crescenta-Montrose homes where decades of ash and dust have accumulated. The sealing itself is done with the system depressurized so we can verify every joint holds. Our 365-Day Done Right Promise covers the seal for a full year; if it fails, we return at no charge.
Look for bare metal, crumbling wrap, or wet spots in your attic ducts. In La Crescenta-Montrose’s shallow attics, degraded insulation is nearly universal on homes built before 1970. We inspect during every sealing estimate and photograph the condition. If the wrap falls apart at a touch, it needs replacement. Bundling insulation with sealing saves on attic access labor and ensures the new seal isn’t undermined by condensation rust six months later. Call (361) 326-5060; we’ll show you exactly what we found.
We typically recommend MERV 11 – 13 for La Crescenta-Montrose homes, high enough to catch fine ash and chaparral pollen but not so restrictive that it strains older HVAC blowers. The real issue is that a high-MERV filter on a leaky duct system is like a mask with holes: the ash bypasses it through gaps in the return plenum and trunk. Seal first, then upgrade filtration. We stock Aprilaire and Guardsman filters sized for common La Crescenta-Montrose systems and can match the right MERV to your blower capacity. Call (361) 326-5060 to schedule.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving La Crescenta-Montrose since 2004.