Fast, Reliable Duct Repair & Sealing Across North Hills
Duct repair and sealing in North Hills, CA typically costs $280-$650 for most residential jobs, with larger acreage properties and detached workshops running $450-$900. Our crew carries enough flex duct, metal trunk material, and mastic sealant to complete most repairs in a single visit, even on the 10-acre spreads off Parthenia and Plummer where a second trip burns half the day. If your ranch-style home or outbuilding is losing airflow, pulling dust from the attic, or running the AC nonstop through July, we’ll get it sealed right and back in service fast. Call (855) 401-6006 for a free estimate and we’ll be there when we say.
We’ve worked the 91343 and 91393 ZIPs for decades. We know the post-war slab ranches along Roscoe Boulevard, the raised-foundation tracts near Sepulveda, and the legacy horse properties stretching toward the Santa Susana foothills. That local knowledge matters when we’re tracing a leak back to a 1994 earthquake repair that never included the ductwork, or when we’re hauling gear down a quarter-mile gravel drive to a detached workshop with a crushed flex run. Roger Castañeda and our team at Bellows Air Duct & Vent Co. treat every North Hills job as if we’re working on our own neighbor’s place, because in this valley, we basically are.
Why Bellows Air Duct & Vent Co. of California Is North Hills’s Preferred Duct Repair & Sealing Company
North Hills homeowners don’t call us for flash. They call because their last contractor showed up late, changed the price, and left the job half-done. We’ve been the square-deal alternative here since 1984. Our Duct Repair & Sealing team answers the phone live, 24 hours a day, no voicemail, no app. A real person schedules your appointment, confirms the upfront price, and dispatches a background-checked, uniformed technician who arrives with the parts already on the truck.
Our reputation in North Hills is built on never needing to be called back. The 90-Day Done Right Promise is stamped on every job in writing: if the seal fails, the flex tears, or the mastic cracks, we return at no charge and no paperwork required. Camera inspection before and after every repair gives you a visual record, not just our word. And we don’t bait-switch with coupons that balloon at the door. The number on the phone is the number on the invoice.
Response time to North Hills runs same-day or next-day for most calls, and we prioritize detached workshop repairs where a down system means no climate control for animals, equipment, or workspace. We stand behind it. No arguing. That’s how we’ve operated for over 42 years.
Our Duct Repair & Sealing Services in North Hills
Duct Sealing
Leaky duct joints in North Hills’s 1950s-1970s ranch homes waste 20-30% of conditioned air into attics and crawl spaces. In the 91343 ZIP, we regularly find trunk lines that were never properly sealed after the ’94 quake, with gaps wide enough to slide a hand through. We seal with mastic compound and reinforced mesh, not tape that dries and fails under attic heat that hits 140°F in August. A typical duct sealing job in North Hills runs $280-$450 for a single system, and we verify the seal with before-and-after camera footage you can see on screen.
Flex Duct Repair
Flex duct is the weak link in most North Hills systems. The fiberglass sleeves degrade, get crushed by storage in attics, or tear at connection points. On acreage properties, detached workshops create a special problem: heavy-duty garage door springs and opener brackets often shift or vibrate against overhead flex runs, splitting the outer liner and collapsing airflow. We sealed a 30-year-old duct run in a detached workshop off Parthenia Street, where heavy-duty garage-door springs had thrown the attic flex-duct out of alignment. We replaced the damaged flex duct, applied mastic to the trunk line, and restored airflow, all in a single extended visit because the 10-acre property made a second trip impractical. Flex duct repair in North Hills typically runs $320-$580 depending on run length and access.
Metal Duct Repair
Original sheet-metal trunk lines in North Hills’s post-war homes are built to last, but their joints and seams are not. The 1994 earthquake sheared connections, cracked elbows, and opened longitudinal seams that were patched with foil tape now failing after thirty years. Long gravel drives to outbuildings shake already-loose metal joints, creating new leaks between the main house and workshop. We repair with proper S-cleats, drive connectors, and mastic sealant, then pressure-test to confirm. Metal duct repair in North Hills runs $380-$650 for trunk line sections, with full replacement rarely needed if caught early.
Mastic Sealant Application
Self-reliant North Hills homeowners sometimes attempt DIY mastic patches that look fine in March but crack and gap by August under the valley’s brutal attic heat. We use professional-grade water-based mastic rated for 250°F continuous exposure, applied with brushes and mesh reinforcement at every joint, seam, and penetration. The application is messy, slow, and permanent. Mastic sealant work on a typical North Hills system runs $260-$420, and it’s often the smartest money you can spend if your ducts are structurally sound but leaking at every connection.
Duct Insulation
Uninsulated or degraded duct insulation in North Hills attics means 10-15°F temperature loss before air ever reaches your vents. Summer temperatures along the Roscoe-Sepulveda corridor regularly surpass 100°F, and attic spaces bake far hotter. We install foil-faced fiberglass insulation or closed-cell foam wraps on repaired ductwork, bringing systems up to current Title 24 standards where practical. Duct insulation in North Hills typically adds $180-$340 to a repair job, and the payback in reduced AC runtime is usually one to two summers.
What happens when you call
- 1
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 North Hills
We stock parts and specify equipment from the brands serious HVAC contractors trust: Rotobrush for duct cleaning and inspection systems, Nikro for HEPA containment and negative air machines, and Abatement Technologies for professional-grade sanitizing and sealing products. For North Hills customers, that means no waiting on special orders from downtown LA. Our trucks carry flex duct, metal fittings, mastic, and insulation in standard sizes, so most repairs finish in the first visit. If your system uses Honeywell or Aprilaire components, we service those too, and we’ll tell you honestly if a part is worth replacing or if the whole section needs reworking. No surprises on the bill.
Common Duct Repair & Sealing Problems We See in North Hills Homes
- Post-quake ductwork left contaminated. Technicians working the 91343 ZIP routinely pull attic panels and find flex duct that was rerouted or hastily patched during post-quake renovations in 1994-1996 but never cleaned. Compacted layers of demolition drywall dust from that repair era are still present inside duct runs, a residue invisible to homeowners who assume their system was “updated” during the rebuild.
- Crushed flex duct in detached workshops. Outdoor workshops with oversized doors often have ductwork that gets crushed by heavy springs or opener brackets, causing tears in flex duct that bleed conditioned air into unconditioned space and pull dust back into the system.
- Shaken metal joints on long service drives. Long service drives, often unpaved, shake loose already-patched metal-duct joints, creating new leaks between the main house and outbuilding that show up as weak airflow and rising energy bills.
- Failed DIY mastic under extreme attic heat. Self-reliant homeowners attempt DIY mastic patches that fail under the valley’s 100°F attic heat, leaving gaps that reintroduce attic dust, insulation particles, and rodent debris into breathing air.
Pricing for Duct Repair & Sealing in North Hills, CA
We’re plain about numbers because nobody likes a bait-and-switch. Here’s what duct repair and sealing costs in the North Hills market:
| Service | Typical Range in North Hills |
|---|---|
| Duct sealing (mastic, single system) | $280 - $450 |
| Flex duct repair/replacement (per run) | $320 - $580 |
| Metal duct repair (trunk line section) | $380 - $650 |
| Mastic sealant application (full system) | $260 - $420 |
| Duct insulation (add-on to repair) | $180 - $340 |
| Large-lot / detached workshop jobs | $450 - $900 |
What moves the needle: accessibility (crawl space vs. walk-in attic), extent of earthquake damage, whether we’re matching existing R-value on insulation, and travel time for outbuilding work on acreage properties. Every estimate is free, every price is locked before we start, and we honor our standing offers: $50 off any repair over $250, free second opinion on any written estimate, $89 seasonal tune-up, and a permanent 5% senior and veteran discount. Call (855) 401-6006 for your exact quote.
We Also Serve Cities Near North Hills
Our crew covers the full San Fernando Valley from our Los Angeles base. We regularly run Duct Repair & Sealing in North Hills and neighboring communities including Northridge, Van Nuys, Valley Glen, and San Fernando. Same upfront pricing, same 90-Day Done Right Promise, same live-answer scheduling wherever you are in the valley.
Serving North Hills, CA - Our Local Coverage Area
We’re based in the North Hills 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 - Duct Repair & Sealing in North Hills
Yes. Our trucks carry 25-foot rolls of flex duct, sheet metal trunk sections, mastic compound, insulation, and connection hardware sized for residential and light commercial systems. For acreage properties off Parthenia and Plummer with detached workshops, we confirm the scope by phone and load extra material specifically for that job. Most large-lot repairs finish in one extended visit. Call (855) 401-6006 to schedule, and we’ll confirm your property details so nothing gets missed.
Typically no. Minor duct repair and sealing inside an existing structure does not trigger Los Angeles County permit requirements. If we’re extending a new trunk line from the main house or altering the HVAC system’s capacity, we’ll flag that during your free estimate and handle any permit coordination. We’ve worked enough North Hills horse properties to know the difference. Call (855) 401-6006 and we’ll walk through your specific setup.
We use water-based duct mastic rated for 250°F continuous exposure, reinforced with fiberglass mesh at all joints and seams. Tape alone fails in North Hills attics within two to three years. Mastic remains flexible, fills irregular gaps, and is the only sealant we guarantee under our 90-Day Done Right Promise. A typical mastic application runs $260-$420. Call (855) 401-6006 for an exact quote on your system.
Yes, and we find this constantly in 91343. Contractors in 1994-1996 prioritized structural and cosmetic repairs; ductwork was rarely cleaned and often only patched where visibly broken. We’ve pulled attic panels and found compacted drywall dust, insulation fragments, and even wood shavings from framing repairs still circulating in systems thirty years later. Our camera inspection shows you exactly what’s inside. Call (855) 401-6006 for a free inspection and estimate.
Yes. Slab-foundation ranches along Roscoe and Sepulveda typically run original sheet-metal trunk lines in the attic or soffit, with flex drops to each room. We repair cracked seams, replace damaged sections, and seal all connections with mastic. Slab homes have no crawl space access, so we work from attic hatches and interior ceiling access where needed. Most slab-ranch metal repairs run $380-$650. Call (855) 401-6006 to schedule.
Ready to stop losing conditioned air to your attic and start breathing cleaner? Call Bellows Air Duct & Vent Co. at (855) 401-6006 for a free estimate on duct repair and sealing in North Hills. We’ll answer live, confirm your upfront price, and get a uniformed technician to your door same day or next. Done right, and backed in writing for 90 days.
Written by Roger Castañeda, Owner at Bellows Air Duct & Vent Co., serving North Hills since 1984.