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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After
Before
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Before
AfterFast, Reliable Duct Sealing Across San Fernando
Duct sealing in San Fernando typically runs $800 – $2,400 per system depending on accessibility, duct material, and whether insulation replacement is needed. Most San Fernando homes need 1 – 3 systems sealed, and we price each one separately so you’re not paying for ductwork that doesn’t exist. Call (361) 326-5060 for a free written estimate before any work starts.
We serve San Fernando from our Los Angeles dispatch office, with crews that know the northeast Valley’s specific housing stock: the 1940s – 1960s tract homes near the San Fernando Mission, the post-war ranches along Maclay Avenue, and the small apartment buildings scattered throughout the city. These aren’t generic houses with generic ducts. They’re older systems baking in 150°F attics, pulling in some of the worst air quality in the LA basin through gaps that formed decades ago. Our technicians arrive uniformed, background-checked, and equipped with Rotobrush inspection systems and professional-grade sealing materials. We show up inside the quoted window, price the job in writing before touching anything, and back it with our 365-Day Done Right Promise.
Why Hollis Air Duct Cleaning Is San Fernando’s Preferred Duct Sealing Company
Hollis Air Duct Cleaning has been part of the Garrison Partners family since 2004, and our Duct Sealing team has built a reputation in San Fernando by solving problems that out-of-area crews miss. We know the difference between a standard flex-duct job in Stevenson Ranch and the original octopus gravity furnace systems still running in homes near the San Fernando Mission. That local knowledge matters when you’re deciding whether to seal, replace, or reconfigure ductwork that was never designed for forced-air cooling.
Our phones are answered by a live person 24 hours a day, 7 days a week. No voicemail loops, no callback queues. When you schedule in San Fernando, we give you a written arrival window and we honor it. The price we write down before work starts is the price you pay. No per-vent add-ons, no surprise charges once the technician is in your attic. Every job is covered by our 365-Day Done Right Promise: if the seal fails or the problem returns within a year, we come back and make it right at no charge, including a free second visit.
San Fernando homeowners choose us because we’ve seen what happens when sealing is done wrong. Foil tape on galvanized steel that expands and contracts in a 150°F attic. Supply joints sealed while the return side leaks worse than before. We document every joint we seal with before-and-after photos, because ductwork is out of sight and you deserve to know what was actually done.
Duct Sealing Services in San Fernando
Duct Sealing Services in San Fernando address the specific failure modes of post-war duct systems: separated seams in galvanized steel runs, torn flex duct in attics, and leaky joints where original gravity furnace ductwork was adapted for forced-air AC. A typical whole-system seal in San Fernando runs $800 – $1,800 for accessible ductwork in a single system, with costs climbing to $2,000 – $2,400 when we encounter multiple systems, extensive attic work, or the need to replace degraded insulation after sealing.
Pressure-Balanced Sealing for Older Systems
San Fernando’s 1940s – 1950s homes weren’t built for central AC. The original octopus gravity furnaces had low-pressure airflow designed for heating, and when homeowners added cooling decades later, the blower pressure often exceeds what those old ducts can handle. We test static pressure before and after sealing to make sure we’re not creating imbalances that starve rooms or overwork the equipment.
Mastic and Mesh on Galvanized Steel
Foil tape fails on San Fernando’s original steel ductwork. The metal expands in morning heat, contracts at night, and tape adhesive gives out within a season. We use duct sealing mastic reinforced with fiberglass mesh on steel joints, creating a flexible seal that moves with the metal. It’s slower than tape. It lasts.
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 San Fernando
Duct Insulation in San Fernando is often the companion job to sealing, because 150°F attics destroy insulation over time and uninsulated sealed ducts still bleed cold air into spaces that don’t need it. Replacing or adding duct insulation after sealing typically adds $400 – $900 per system in San Fernando, depending on linear footage and whether we’re working in an accessible attic or a tight crawlspace. Homes near the San Fernando Mission with original octopus systems often need both: the sealing stops air loss, the insulation stops thermal loss.
R-Value Matching for Valley Heat
San Fernando’s climate demands R-6 or R-8 insulation on supply ducts, minimum. We see too many jobs where a crew sealed the joints but left R-4 or uninsulated flex duct in a 140°F attic. The air arrives lukewarm, the AC runs longer, and the homeowner thinks the seal failed. We match insulation rating to the thermal load.
Vapor Barrier Integrity
Old insulation in San Fernando attics often has torn vapor barriers that let moisture condense on cold duct surfaces. We replace damaged sections with new wrapped insulation, sealed at seams, so you’re not trading air leaks for condensation problems that grow mold.
Trusted Brands We Service in San Fernando
We carry professional-grade sealing and insulation materials from Nikro, Honeywell, and Aprilaire, stocked for fast turnaround on San Fernando jobs. Our equipment roster includes Rotobrush rotary brush systems for pre-seal cleaning and camera inspection, Nikro negative-air machines for debris control during the work, and Honeywell and Aprilaire filtration components for homeowners who want to address air quality at the same time they fix duct leakage. We don’t use hardware-store tape or bulk-bin mastic. The materials matter when your attic hits 150°F and the seal needs to last.
Common Duct Sealing Problems We See in San Fernando Homes
- Visible-joint-only sealing. A crew seals the registers and air handler connections you can see, then leaves the long attic runs untouched. In San Fernando’s 1940s – 50s homes, those hidden runs are where 60% of leakage happens. The pressure imbalance persists, and your AC still runs nonstop.
- Foil tape on galvanized steel. Tape is fast and cheap, which is why low-bid crews love it. On original San Fernando steel ductwork that cycles through 100°F temperature swings daily, the adhesive fails within months. We find these “reseals” every year.
- Supply-side-only work. Older San Fernando tract homes often have a single undersized panned-joist return. Seal the supplies without addressing return capacity, and the blower starves for air. It pulls harder on every remaining leak, including gaps that draw in attic dust and smog from the Valley’s heavy air pollution.
- Ignoring the octopus system legacy. Homes near the San Fernando Mission with original gravity furnace ductwork have low-pressure, oversized runs that behave nothing like modern flex duct. Sealing them like standard forced-air systems creates backpressure and uneven room-to-room airflow.
Pricing for Duct Sealing in San Fernando, CA
Honest pricing for San Fernando duct sealing looks like this: a single accessible system with standard flex duct runs $800 – $1,200 to seal. Two-system homes common in the larger ranches near the 91340 zip code run $1,400 – $2,000. Original galvanized steel systems in Mission-area homes, or jobs requiring extensive attic navigation, reach $2,000 – $2,400. Duct insulation added after sealing runs $400 – $900 per system.
What moves the price: accessibility (crawlspace vs. walkable attic), duct material (flex is faster to seal than rigid steel), number of systems, and whether we’re replacing degraded insulation as part of the job. We do not price per vent. We price per system, agreed in writing before work starts, and that number does not change at your door. Every estimate includes a camera inspection so we both know what we’re dealing with. Call (361) 326-5060 to schedule yours.
We Also Serve Cities Near San Fernando
Our crews regularly work in San Fernando and the surrounding communities: Burbank to the southeast, Santa Clarita and Stevenson Ranch to the north, and Glendale to the east. Each area has its own duct characteristics, from Burbank’s hillside homes with long vertical runs to Santa Clarita’s newer construction with modern flex systems. We adjust our approach to the housing stock, not force one method everywhere.
Serving San Fernando, CA - Our Local Coverage Area
We’re based in the San Fernando 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 San Fernando
Because many San Fernando homes have multiple independent systems or zoned additions added decades after original construction, and a flat rate would have you paying for ductwork that doesn’t exist or underpaying for a complex multi-system job. We inspect and price each system separately so the written estimate matches your actual house. Call (361) 326-5060 for an exact quote.
San Fernando sits in one of the LA basin’s most polluted air corridors, and leaky return ducts actively pull that outdoor air into your system every time the blower runs. Sealing without testing return-side integrity can actually increase infiltration by creating stronger negative pressure. We test both sides.
You should receive before-and-after photos of sealed joints, a written list of every location addressed, pressure test results if performed, and your 365-Day Done Right Promise in writing. Ductwork is hidden. Documentation is how you know the work happened and how you hold us accountable if it fails.
Yes, but it requires a different approach than standard forced-air sealing. Octopus systems run at lower static pressure with larger diameter runs, and sealing them for modern AC blower pressure risks creating backpressure and uneven airflow. We inspect first, test pressure capacity, and recommend sealing only where the existing ductwork can handle it.
Sealing stops air loss; insulation stops the cold air from warming up before it reaches your rooms. In San Fernando’s 150°F attics, sealed but uninsulated ducts still waste energy. We typically seal first, verify with a pressure test, then add or replace insulation on the longest runs so you’re not losing the battle to attic heat.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving San Fernando since 2004.