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 Belmont
Duct sealing in Belmont, MA typically runs $1,200 – $2,800 for a whole-home system depending on access and the condition of your original ductwork. Most Belmont jobs take a full day because the homes here, mostly built from the 1940s through the 1970s, have galvanized steel trunks and flex runs in crawlspaces that need more than tape to fix properly. We’re Hollis Air Duct Cleaning, and our crews serve Belmont from our Boston office, carrying the same Rotobrush and Nikro equipment we use on commercial jobs. If you’re seeing soot streaks on your registers, smelling smoke after wildfire season, or certain rooms never get warm, the problem is usually disconnected or leaking ductwork, not your furnace. Call us at (361) 326-5060 and we’ll show you exactly what’s failing before we quote a price.
Why Hollis Air Duct Cleaning Is Belmont’s Preferred Duct Sealing Company
We’ve been working in Belmont long enough to know the difference between a 1950s ranch on the hillside and a two-story traditional closer to the town center. The duct systems fail differently in each, and our technicians are trained to spot which problem you’ve got before we touch anything. Our Duct Sealing in Belmont work is backed by the 365-Day Done Right Promise in writing on every job, if the seal fails, we come back at no charge, including a free second visit.
Belmont homeowners call us because we’ve built a reputation on showing up inside the window, pricing in writing before any work starts, and leaving the site clean. Our background-checked, uniformed technicians arrive with professional-grade equipment from Rotobrush, Nikro, and Abatement Technologies, the same tools commercial crews use, not hardware-store gear. Phones are answered by a live person 24 hours a day, 7 days a week. No voicemail loops. No callback queues.
Duct Insulation in Belmont
Duct Insulation in Belmont is often the missing piece after sealing is done, because sealing the leaks doesn’t help if your ducts run through an unconditioned crawlspace or attic where the marine layer keeps everything damp six months a year. A typical duct insulation job in Belmont runs $800 – $1,800 depending on linear footage and whether we’re working with rigid galvanized trunk lines or flexible branch runs. We use closed-cell foam and fiberglass wraps rated for the temperature swings these ducts see, and we always inspect the vapor barrier condition first.
When Insulation Beats Replacement
Many Belmont homes have original galvanized plenums that are structurally sound but thermally naked. Wrapping them properly cuts heat loss and stops condensation that leads to mold. We see this especially in crawlspace systems near Belmont’s western hills, where the marine air sits heavy.
Vapor Barrier Integrity
If the existing insulation’s vapor barrier is torn, water gets in and stays in. We strip compromised wraps, seal the metal beneath, then reinsulate with a continuous barrier. Skipping this step is why some Belmont homeowners smell musty air even after a full duct cleaning.
HVAC Duct Sealing in Belmont
HVAC Duct Sealing in Belmont requires understanding how this town’s original gravity-furnace duct systems were retrofitted for modern high-static air handlers, because the mismatch is where most leaks start. A typical HVAC duct sealing job in Belmont runs $1,200 – $2,400 for standard access, or up to $2,800 if we need to work in tight crawlspaces under homes on the hillside streets off Alameda de las Pulgas or near Belmont Canyon. We use mastic and mesh on metal joints, proper mechanical fasteners on flex collars, and we always pressure-test afterward to confirm the seal holds under operating static.
Static Pressure and Collar Failures
The undersized hard-duct trunks in Belmont’s mid-century homes create pressure spikes at distant registers. That pressure pulls flex takeoffs apart at their crimped collars, especially after any crawlspace work. Taping over the gap doesn’t fix the pressure problem. We resize or balance what we can, then seal with materials that flex without failing.
Smoke Event Recovery
After Santa Cruz Mountains wildfires, we find fine ash coating the inside of flex ducts even when filters were changed religiously. Sealing alone doesn’t remove the residue, so we often pair sealing with source removal using HEPA filtration and agitation tools. Then we seal the system so it doesn’t happen again.
Trusted Brands We Service in Belmont
Our Belmont crews carry parts and sealing materials compatible with systems using Honeywell, Aprilaire, and Guardsman filtration components, plus the full Rotobrush and Nikro equipment line for cleaning and prep work before sealing. We don’t guess at what fits your plenum or trunk size. We stock mastic, mesh, mechanical fasteners, and insulation wraps sized for the 6-inch to 14-inch diameters common in Belmont’s original galvanized systems, so we’re not ordering parts and coming back next week. That matters on hillside jobs where parking is tight and you don’t want the truck making a second trip.
Common Duct Sealing Problems We See in Belmont Homes
- Foil tape peeling off galvanized trunks. Belmont’s temperature swings, hot dry summers inland, cool damp winters near the bay, make metal duct expand and contract. Foil tape applied without mastic and mesh cracks within one heating season. We see this constantly on original 1950s and 1960s systems in the Belmont hills.
- Crushed flex collars in crawlspaces. The narrow hillside streets and tight crawlspaces in western Belmont mean previous repairs often crushed flex duct collars against joists or foundation walls. Sealing the crush without rebuilding the collar just creates a new restriction that blows apart under pressure.
- Disconnected runs pulling marine-layer air. Original 1940s-1970s galvanized duct in attics and crawlspaces separates at joints over decades. We camera-inspect first, because sealing only the accessible registers leaves disconnected runs sucking damp air and promoting mold.
- Smoke residue reactivating seasonally. After wildfire events, fine ash embeds in porous flex duct liner. Changing the filter doesn’t touch it. Sealing the system after proper source removal is the only way to stop the smell from cycling back through registers every time the heat kicks on.
Pricing for Duct Sealing in Belmont, MA
A typical whole-home duct sealing job in Belmont runs $1,200 – $2,400 for homes with accessible basements or crawlspaces, and $2,000 – $2,800 for hillside properties with tight access, extensive galvanized trunk work, or multiple disconnected runs requiring camera location and rebuild. Duct insulation added after sealing runs $800 – $1,800 depending on linear footage. What moves the price: how much of your system is original galvanized versus flex, whether we need to rebuild crushed collars or just seal joints, and whether smoke or mold remediation is needed before we seal.
We give you one flat price per system, agreed in writing before any work starts. No per-vent pricing. No add-ons at the door. You’ll see before-and-after photos of your own ducts, and the static pressure test results, before we consider the job complete. Estimates are free. Call (361) 326-5060 to schedule.
We Also Serve Cities Near Belmont
Our Duct Sealing crews regularly work in Arlington, Cambridge, Newton, and Waltham, but Belmont’s specific mix of mid-century ranchers, hillside crawlspace systems, and wildfire smoke exposure creates sealing challenges we know intimately. The same Garrison Standard applies in every town: arrive inside the window, price in writing, complete the job by the book, leave the site clean.
Serving Belmont, MA - Our Local Coverage Area
We’re based in the Belmont 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 Belmont
Most 1950s galvanized ducts in Belmont can be sealed successfully if the metal isn’t rusted through or structurally compromised. We camera-inspect first to check for separated joints, holes from corrosion, or crushed sections. If the trunk is sound, we clean with negative-air HEPA methods, then seal with mastic and mesh at all joints and rebuild any damaged flex collars. Replacement becomes necessary only when the metal itself is failing, which we can show you on camera. Call (361) 326-5060 for a free inspection and exact quote.
The fine ash particles from Santa Cruz Mountains wildfires coat the inside of flexible duct liners and embed in porous insulation, bypassing standard HVAC filters entirely. Changing the filter protects the equipment but doesn’t clean the duct interior. We remove the residue with HEPA vacuuming and agitation tools, then seal the system to prevent re-infiltration. The smell stops when the source is gone and the path is closed. Call (361) 326-5060 to schedule source removal and sealing before the next fire season.
We run a video camera through the duct system from the register or plenum end, which shows us separated joints, collapsed flex, or crushed collars in real time without cutting access holes. In Belmont’s tight hillside crawlspaces, this saves hours of destructive exploration. We record what we find and show you before we quote any repair. Call (361) 326-5060 to book a camera inspection.
Sealing helps with mold and dampness only if the ducts are also properly insulated with intact vapor barriers. Belmont’s marine-layer moisture gets pulled into leaky, uninsulated ducts running through crawlspaces, creating condensation that feeds mold growth. We seal the leaks first, then reinsulate with proper vapor barriers where needed. Sealing alone without addressing insulation and drainage in the crawlspace won’t solve a mold problem. Call (361) 326-5060 and we’ll assess whether you need sealing, insulation, or both.
NADCA, the National Air Duct Cleaners Association, sets protocols for how duct systems are accessed, cleaned, and sealed to avoid contaminating the living space during work. For your Belmont home, it means we use contained negative-air methods, HEPA filtration on our equipment, and proper post-job verification so we’re not blowing debris into your rooms or leaving leaks that pull in crawlspace air. We follow these standards on every job, documented in writing. Call (361) 326-5060 to ask about our process or schedule service.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Belmont and the greater Boston area since 2004.