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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Before
AfterFast, Reliable Duct Sealing Across San Marino
San Marino homeowners know their homes aren’t standard construction. Most were built between 1920 and 1970, many by prominent architects, with original gravity or early forced-air ductwork that predates modern HVAC standards. Duct sealing in San Marino typically runs $1,200 – $2,800 for a whole-home seal, depending on system accessibility and the condition of original runs. We’re familiar with the tight attic chases off Lorain Road, the raised foundations near Huntington Drive, and the unlined sheet-metal branches that snake through these historic properties. Our Duct Sealing team dispatches from our Los Angeles office and serves San Marino with background-checked, uniformed technicians who arrive inside the quoted window, price the job in writing before touching anything, and leave the site clean. Call (361) 326-5060 for a free estimate.
Why Hollis Air Duct Cleaning Is San Marino’s Preferred Duct Sealing Company
We’ve worked on enough San Marino homes to know the difference between a routine seal and a preservation retrofit, including specialized services like our San Marino Dryer Vent Cleaning. The city’s strict architectural review and preservation-minded homeowners mean ductwork here is treated as a historical asset, not disposable infrastructure. That constraint shapes how we approach every job.
Our technicians carry mastic, foil tape, and mechanical fasteners suited to original sheet-metal runs, not just modern flex duct. We’ve sealed systems in the estates near Oak Knoll and the ranchers off Monterey Road, and we’ve learned which fittings fail first in this housing stock. The 365-Day Done Right Promise covers every seal we perform: if a joint opens, a trunk sags, or a plenum leaks within a year, we return and make it right at no charge, including a free second visit.
Phones are answered by a live person 24 hours a day, 7 days a week. No voicemail loops. No callback queues. When you schedule Duct Sealing in San Marino, you get a written price before work starts and a crew that shows up uniformed, on time, and accountable.
Duct Repair in San Marino
Duct Repair in San Marino often means fixing what decades of remodels, rodent activity, and wildfire ash have damaged in original systems rather than replacing them outright. The job involves locating disconnected or crushed runs, re-supporting sagging trunks, replacing degraded flex connections, and sealing all accessible joints with mastic or foil tape. A typical repair in San Marino runs $400 – $1,100 for accessible work, with complex attic or crawl-space jobs reaching $1,500 – $2,200 if we need to navigate tight chases in 1920s construction.
Disconnected Trunks and Crushed Runs
On Lorain Road we opened a 1926 estate’s unlined attic chase and found the main trunk separated at a fitting, rodent nests packed against the collar, and Bobcat Fire ash still layered inside the original sheet-metal run. After source removal under negative pressure with HEPA filtration, we camera-inspected the branch runs, then mastic-sealed the plenum and every accessible joint and re-supported the sagging trunk. Supply and return ducts held pressure afterward, and the blower motor stopped short-cycling against the leaky static.
Re-Supporting Original Sheet-Metal
Gravity systems from the 1930s and 1940s often hang from straps that have corroded or pulled free. We replace supports with hardware that won’t damage plaster ceilings below, then seal the new connections without disturbing original finishes.
Air Duct Sealing in San Marino
Air Duct Sealing in San Marino is frequently a preservation project rather than a standard maintenance call. The city’s preservation-minded architectural review means ductwork – not equipment – is treated as the historical asset to save, a constraint virtually absent in neighboring San Gabriel Valley cities where ductwork is more often torn out and rebuilt. Sealing involves coating joints, seams, and plenum connections with mastic, applying foil tape to accessible trunk lines, and pressure-testing the system to verify integrity. Whole-home sealing in San Marino typically costs $1,200 – $2,800, with partial seals of accessible trunk-and-branch systems starting around $800.
Mastic Application on Original Systems
Mastic is a water-based sealant that remains flexible after curing, making it ideal for original sheet-metal that expands and contracts with temperature swings. We brush or trowel it onto every accessible joint, collar, and plenum seam, then verify coverage with a borescope camera before closing access panels.
Pressure Testing After Seal
We run a duct blaster or manometer test after sealing to quantify improvement. A typical pre-seal San Marino system leaks 25 – 40 percent of conditioned air into attics and wall cavities. A proper seal should cut that to 10 percent or less, measurable on our gauges before we leave.
Trusted Brands We Service in San Marino
Our equipment roster includes Nikro negative-air machines for source removal, Honeywell and Aprilaire filtration components for post-seal air quality improvement, and Abatement Technologies HEPA containment for jobs where asbestos-wrapped ductwork or degraded liner is present. We stock mastic, foil tape, mechanical fasteners, and replacement collars sized for original sheet-metal dimensions that big-box stores don’t carry. For San Marino homeowners, that means faster turnaround on repairs and seals that match existing materials rather than forcing modern flex duct into historic chases. When we seal a 1940s plenum or re-support a 1930s trunk, we use products rated for the application, not whatever’s on the van floor.
Common Duct Sealing Problems We See in San Marino Homes
- Mastic slapped over crushed or disconnected runs. Some crews seal what they can reach without checking continuity. The leak doesn’t close; it moves. We camera-inspect before sealing to confirm the duct is intact and continuous.
- Sealing the plenum while ignoring unlined attic branches. A 1960s rancher near Monterey Road may have a tight trunk but original branch runs full of rodent debris and Bobcat Fire ash. Sealing the trunk traps that contamination in the system. We source-remove first, then seal.
- Standard residential vacuums on decades-old ductwork. Shop vacs can’t pull loose particulate off duct walls the way source removal under negative pressure does. Our Nikro negative-air machines create suction at the duct wall, not just at the nozzle.
- Replacing original systems that could be preserved. San Marino’s architectural review often makes replacement more complicated than sealing. We evaluate whether a retrofit seal meets performance goals before recommending tear-out, saving homeowners time and preserving historical fabric.
Pricing for Duct Sealing in San Marino, CA
Here’s what duct sealing costs in San Marino’s market:
| Service | Typical Range |
|---|---|
| Partial seal (accessible trunk + plenum) | $800 – $1,400 |
| Whole-home seal (standard accessibility) | $1,200 – $2,200 |
| Whole-home seal with complex attic/crawl work | $2,000 – $2,800 |
| Duct repair (disconnected/crushed run) | $400 – $1,100 |
| Extensive repair with re-support and sealing | $1,500 – $2,200 |
What moves the price: accessibility of attic chases, presence of asbestos wrapping requiring containment, extent of rodent damage needing repair before seal, and whether original fittings are intact or need custom fabrication. We price every job in writing before starting work. One flat price per system. No per-vent add-ons, no equipment charges that appear after we’re inside. Estimates are free. Call (361) 326-5060 to schedule.
We Also Serve Cities Near San Marino
Our crews work throughout the San Gabriel Valley, including San Marino neighbors in San Gabriel, Alhambra, Pasadena, and South Pasadena. Each community has distinct housing stock and duct configurations, and we adjust our approach accordingly. San Gabriel’s mid-century apartments, Alhambra’s mixed-era subdivisions, Pasadena’s Craftsman bungalows, and South Pasadena’s Victorian conversions each present different sealing challenges than San Marino’s architect-designed estates.
Serving San Marino, CA - Our Local Coverage Area
We’re based in the San Marino 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 Marino
Yes, original 1930s ductwork in San Marino can often be sealed rather than replaced, and preservation review frequently makes this the preferred path. We camera-inspect the full system first to confirm continuity, then mastic-seal accessible joints and re-support any sagging sections. If the metal is corroded through or crushed beyond repair, we’ll show you the damage and discuss options. Call (361) 326-5060 for an exact quote – estimates are free.
San Marino’s combination of Santa Ana winds, wildfire ash from events like the 2020 Bobcat Fire, and original unlined attic ductwork creates faster accumulation than in cities with newer flex-duct systems and less exposure to seasonal fire debris. The mild climate also means HVAC runs year-round, so ducts never get a long rest period. Call (361) 326-5060 for an exact quote – estimates are free.
It can be. We’ve found Bobcat Fire ash layered inside original sheet-metal runs on homes near Lorain Road and Huntington Drive, especially in unlined attic chases where standard residential vacuums never reached it. Source removal under negative pressure with HEPA filtration is the only method that pulls that material off duct walls. Call (361) 326-5060 for an exact quote – estimates are free.
Rodent nests compress against collars and fittings, creating gaps that mastic alone can’t bridge. We remove nests and debris under negative pressure, repair or replace damaged fittings, then seal the restored joints. Sealing over nests traps contamination and guarantees failure. Call (361) 326-5060 for an exact quote – estimates are free.
Yes, if the ducts are clean first and properly sealed after. Sealing alone doesn’t remove existing debris, but it prevents attic dust, pollen, and wildfire ash from being drawn into the system through leaks. In San Marino’s older homes, we typically recommend source removal, then sealing, then verification with pressure testing. Call (361) 326-5060 for an exact quote – estimates are free.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving San Marino since 2004.