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 Florence-Graham
Duct sealing in Florence-Graham typically runs $800 – $2,400 for a whole-system seal on a standard bungalow or fourplex, with most jobs scheduled within a few days and completed in one visit. We’re the Florence-Graham crew from Hollis Air Duct Cleaning, and we know this unincorporated pocket of South LA. Our technicians drive the grid from Florence Avenue down to Santa Fe Avenue, past the compact 1920s bungalows and fourplexes where the same ducts have been leaking since Truman was president. Because our Los Angeles office coordinates dispatch locally, we can quote your job and get it on the calendar without the runaround. Call (361) 326-5060 and you’ll reach a live person, any time.
Why Hollis Air Duct Cleaning Is Florence-Graham’s Preferred Duct Sealing Company
We’ve been in business since 2004 as part of the Garrison Partners family, and our Duct Sealing team has worked enough Florence-Graham properties to know the pattern: wall furnaces, undersized returns, shared crawlspaces, and black debris that tenants have learned to ignore. Our technicians are background-checked and uniformed, and they arrive inside the quoted window because The Garrison Standard says we show up when we said we would.
Every job gets a written price before any work starts. Not an estimate that balloons once we’re inside. The number on the page is the number at the door. Our 365-Day Done Right Promise covers every seal in writing: if it fails within a year, we come back and make it right at no charge, including a free second visit. That promise matters in Florence-Graham, where many renters and small landlords have been burned by crews who disappeared after cashing the check.
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 find out if someone can look at your ducts.
Air Duct Sealing in Florence-Graham
Air Duct Sealing in Florence-Graham means closing the gaps, cracks, and disconnected joints in your supply and return ductwork so the air you paid to heat or cool actually reaches the rooms it’s supposed to. In this neighborhood’s 1920s – 1960s housing stock, we see the same problems repeatedly: original wall and floor furnaces with undersized ducts routed through shared crawlspaces, returns that were added later and never properly sealed, and cross-unit contamination in fourplexes where one tenant’s cooking smoke or bathroom moisture migrates through open wall cavities.
Most Florence-Graham homeowners and landlords need duct sealing when they notice uneven temperatures, rising utility bills, or visible black debris blowing from registers before heat waves. The LA Basin climate doesn’t force the issue the way Phoenix or Fresno would, so ducts here collect fine grit year-round and rarely get attention until something breaks. Typical whole-system sealing runs $800 – $2,400 depending on accessibility and the extent of leaks found during inspection.
Sealing Shared-Wall Systems
In the dense fourplexes along Florence and Santa Fe Avenues, duct sealing often means isolating each unit from its neighbors. Shared wall and roof cavities connect units that were never meant to share air. We seal the perimeter of each unit’s duct runs with mastic and mesh, then verify isolation with pressure testing. Without this step, new seals on one unit’s supply ducts do nothing to stop the neighbor’s debris from migrating through the returns.
Crawlspace and Attic Returns
Many Florence-Graham bungalows have return ducts that were retrofitted through crawlspaces or attics and never properly connected to the air handler. These leaks pull in fiberglass insulation, rodent droppings, and soil moisture. We seal these connections with code-compliant mastic rated for the temperature swings in unconditioned spaces, then verify with a smoke pencil or camera inspection.
Duct Sealing Services in Florence-Graham
Duct Sealing Services in Florence-Graham cover the full range of leak repair, from register boots and plenum connections to complete system sealing with post-work verification. Our crews use professional-grade equipment: Rotobrush rotary systems for access and cleaning before sealing, Nikro negative-air machines to maintain pressure containment during the job, and sealing products from Abatement Technologies and Guardsman rated for residential ductwork.
The work starts with a camera inspection and pressure test to map the leaks. We then clean the accessible duct surfaces, apply mastic and reinforced mesh to joints and seams, and seal register boots to the drywall or floor. For Florence-Graham’s older stock, we often find that the original ducts are too small for modern HVAC loads; in those cases, we’ll tell you straight and quote replacement separately rather than seal a system that can’t perform.
Pre-Sealing Cleaning Protocol
Sealing dirty ducts traps debris inside. We use a Rotobrush rotary brush system with HEPA-contained vacuuming to remove the black grit and fine dust that collects in Florence-Graham ducts before we seal any surface. This step is non-negotiable on our jobs. The Garrison Code requires it.
Post-Seal Verification
After sealing, we run a second pressure test and provide before-and-after photos of the work. In Florence-Graham’s rental market, these photos protect landlords from tenant disputes and give renters documentation to show property managers who’ve been slow to address air quality complaints.
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.
Trusted Brands We Service in Florence-Graham
Our vans carry sealing and filtration products from Abatement Technologies, Guardsman, Honeywell, and Aprilaire. We stock mastic, mesh, and register boots sized for the smaller duct diameters common in Florence-Graham’s pre-1960s housing, so we’re not ordering parts and making you wait. For properties with newer HVAC additions, we source compatible fittings for Honeywell and Aprilaire filtration upgrades that integrate with sealed duct systems. The goal is one visit, done right, with no callbacks for missing materials.
Common Duct Sealing Problems We See in Florence-Graham Homes
- Sealed supplies, leaking returns. A crew seals the visible register boots but leaves the undersized return ducts in the crawlspace or attic wide open. The system still pulls in contaminated air, and the homeowner sees no improvement. We find this in about half the 1920s – 1950s bungalows we inspect in Florence-Graham.
- Cross-unit contamination in fourplexes. The dense housing along Florence and Santa Fe Avenues means shared wall and roof cavities connect units that were never properly isolated. Sealing one unit’s ducts without addressing these pathways is like fixing half a screen door.
- Attic-vented bathroom fans. Bathroom exhaust fans that vent into the attic or wall cavity dump lint and moisture directly into the same zone as the air handler and ductwork. New seals fail or mold returns if this venting isn’t corrected before or during duct sealing.
- Fine grit accumulation from LA Basin air. Santa Ana winds and year-round dry conditions pull dust, pollen, and smog particles through window gaps and return-air leaks. Ducts here collect this grit continuously, and without sealing, it recirculates through living spaces every time the system runs.
Pricing for Duct Sealing in Florence-Graham, CA
Whole-system duct sealing in Florence-Graham runs $800 – $2,400 for typical bungalows and two- to four-unit buildings. Smaller jobs, like sealing accessible register boots and plenum connections on a single wall furnace, start around $400 – $650. Larger fourplexes with multiple air handlers, extensive crawlspace work, or cross-unit isolation requirements can reach the upper end.
| Job Type | Typical Range |
|---|---|
| Single wall furnace, register boots and plenum | $400 – $650 |
| Whole-system seal, standard bungalow | $800 – $1,400 |
| Fourplex with cross-unit isolation | $1,600 – $2,400 |
| Post-seal pressure test and documentation | Included |
What moves the price: accessibility (crawlspace height, attic hatch location), extent of leaks found during inspection, whether pre-sealing cleaning is needed, and whether bathroom venting or other connected issues require correction. We write the price down before any work starts, and it does not move at the door. Estimates are free. Call (361) 326-5060 for an exact quote on your property.
We Also Serve Cities Near Florence-Graham
Hollis Air Duct Cleaning dispatches Duct Sealing in Florence-Graham from our Los Angeles office, and we regularly serve Los Angeles, San Diego, San Jose, and San Francisco with the same written pricing and 365-Day Done Right Promise. Each location is independently owned and operated under The Garrison Standard.
Serving Florence-Graham, CA - Our Local Coverage Area
We’re based in the Florence-Graham 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 Florence-Graham
Every 5 – 7 years for cleaning, with sealing inspected at the same interval and redone when pressure testing shows leakage above 15% of total airflow. The fine grit from LA Basin air and Santa Ana winds accumulates steadily, and the mild climate means homeowners don’t get a forced reminder from extreme heating or cooling bills. Call (361) 326-5060 to schedule an inspection and we’ll test whether your current seals are holding.
It stops cross-unit contamination by isolating each unit’s ductwork from shared wall and roof cavities. Without sealing, your neighbor’s cooking smoke, bathroom moisture, or debris migrates through open connections into your supply and return air. We verify isolation with pressure testing after sealing. For an assessment of your specific building, call (361) 326-5060.
Yes, significantly. Attic-vented fans dump lint and moisture into the same zone as your air handler and ductwork, which defeats new seals and promotes mold on sheathing. We correct this venting before or during duct sealing, routing the fan to exterior termination. The cost depends on attic access and run length; we’ll include it in your written quote. Call (361) 326-5060 for details.
No. Florence-Graham has no municipal building department, so there’s no permit or inspection trigger for residential duct sealing. The work is typically driven by renters or small landlords responding to visible debris at registers or tenant complaints. We provide before-and-after photos and pressure test documentation in lieu of official inspection. Call (361) 326-5060 to discuss documentation for your property manager or landlord.
Uneven temperatures between rooms, utility bills that rise without rate increases, visible gaps at register boots, or black debris that returns within months after cleaning. In Florence-Graham’s older stock, disconnected returns in crawlspaces and shared-wall leakage are the most common causes. A pressure test distinguishes sealing needs from cleaning needs. Call (361) 326-5060 for a free inspection and we’ll tell you which applies.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Florence-Graham since 2004 as part of the Garrison Partners family.