Duct Repair & Sealing in Lewisville - Leakage Measured, Then Priced in Writing

Trusted Duct Repair & Sealing for Lewisville Homeowners

Duct repair and sealing in Lewisville typically costs $280-$890 depending on whether the job involves spot sealing with mastic, replacing a damaged flex duct run, or resealing an entire metal trunk line. Most residential repairs we complete in Lewisville take 2-4 hours, and every job starts with a written price before any work begins. Call (940) 240-8552 for a free estimate with no obligation to schedule.

Call (940) 240-8552

We’ve been repairing and sealing ductwork in Lewisville since 2013, and the pattern we see hasn’t changed: conditioned air escapes through gaps the homeowner can’t see, the HVAC system runs longer to compensate, and utility bills climb month after month. In the older neighborhoods near Old Town Lewisville and the newer construction around Castle Hills, we’ve documented the same problems with our camera systems - disconnected flex ducts in attics, failed tape at plenum connections, and metal seams that have worked open after years of thermal expansion. Every repair we perform concludes with a photo record of what we found and what we fixed, delivered as part of the standard job documentation. That’s Haven Standard Clause 1: Written Price Before Work Starts, and it’s been non-negotiable since our first job.

What Our Duct Repair & Sealing Service Includes

Duct Sealing

Duct sealing closes the gaps, cracks, and disconnected joints that leak conditioned air into your attic, crawl space, or wall cavities. In Lewisville, we commonly find that 20-30% of heated or cooled air never reaches the registers it was meant for, especially in homes built during the 1990s and 2000s construction boom. Our crew applies mastic sealant - a thick, brush-applied compound that remains flexible after curing - to every accessible joint and seam, then verifies the seal with a pressure test when the system configuration allows. We use professional-grade sealants from trade-recognized manufacturers, and we photograph every sealed connection before closing the access panel.

Flex Duct Repair

Flex duct, the insulated flexible tubing common in residential attics, degrades from UV exposure, pest activity, and physical compression from storage or maintenance traffic. In Lewisville homes with attic HVAC installations, particularly in the Creekview and Valley Vista areas, we’ve replaced flex ducts that had collapsed entirely or developed tears where they rested against rafter edges. Our repair process removes the damaged section, installs a properly sized replacement with metal sleeve connectors, and suspends the new run from straps to prevent future sagging or compression. Every flex duct repair is pressure-tested before we leave, and the photo record shows the old material alongside the new installation.

Metal Duct Repair

Metal ductwork - galvanized steel or aluminum trunk lines and branch ducts - can corrode at seams, separate at joints due to thermal cycling, or sustain damage from renovation work or pest intrusion. We’ve repaired metal ducts in Lewisville homes where rust had eaten through the bottom of a trunk line in a humid crawl space, and where a previous contractor’s sheet metal screws had backed out over years of vibration. Our metal duct repairs involve cutting out damaged sections, fabricating replacement pieces to fit, and sealing all joints with mastic and fiberglass mesh reinforcement. The result is a repair that matches the durability of the original installation, documented with before-and-after photos of the metalwork.

Duct Insulation

Duct insulation prevents thermal loss as conditioned air travels through unconditioned spaces - attics in Lewisville can reach 140°F in July, and crawl spaces drop below freezing during hard winter snaps. We replace degraded or missing insulation on both flex and metal ductwork, using products rated for the temperature extremes of North Texas climate zones. In homes near Lewisville Lake where humidity runs higher, we pay particular attention to vapor barrier integrity, since compromised barriers allow condensation that accelerates mold growth and duct corrosion. The insulation we install is photographed at multiple points to confirm complete coverage and proper sealing of the vapor barrier jacket.

Mastic Sealant Application

Mastic sealant is the industry-standard material for durable, long-lasting duct sealing - unlike foil tape, which degrades and peels, mastic remains flexible and adherent for the life of the duct system. We apply mastic with brushes and trowels to ensure complete coverage at every joint, elbow, and register boot connection, building up a seal that withstands the pressure pulses of modern variable-speed blowers. In Lewisville, where many homes have two-story designs with long duct runs to second-floor bedrooms, proper mastic application at every intermediate joint is critical to delivering full airflow to distant registers. Our application technique follows manufacturer specifications for thickness and cure time, and we document the work with photos showing the mastic bead before it cures.

Air Leak Repair

Air leak repair addresses the specific points where your duct system loses pressure - not just at designed joints, but at penetrations for wiring, plumbing, or structural members that were never properly sealed during construction. We locate these leaks using a combination of visual inspection, pressure testing, and in some cases thermal imaging to identify temperature anomalies along duct runs. In Lewisville’s newer subdivisions, we’ve found that builder-grade installations often omit sealing at register boots where they pass through drywall, creating a direct path for attic air to enter living spaces. Every leak we repair is cataloged in the job documentation with a photo showing the before condition, the repair method, and the finished seal.

Signs You Need Duct Repair & Sealing Right Now

• Uneven temperatures from room to room. If your master bedroom runs 6-8 degrees warmer than the living room in summer, or your upstairs never reaches the thermostat setpoint, the duct system is likely leaking or obstructed rather than properly distributing air. We’ve traced these complaints in Lewisville to disconnected flex ducts, crushed runs from storage activity, and leaks at plenum connections that had gone unnoticed for years.
• Dust accumulation near registers or shortly after cleaning. When ducts pull air from the attic through leaks on the return side, they introduce fiberglass particles, insulation fragments, and attic dust that bypass the filter entirely. In homes near the construction zones along SH 121 and I-35E, we’ve also seen fine road dust enter through compromised duct seals during high-wind events.
• Utility bills that rise without explanation. A duct system leaking 25% of its air forces the HVAC equipment to run longer cycles to achieve the same temperature, and longer cycles mean higher kilowatt-hour or therm consumption. We regularly meet Lewisville homeowners who’ve replaced perfectly good equipment when the real problem was duct leakage that a $400-$700 sealing job would have solved.
• Hissing or whistling sounds from ducts or registers. These noises indicate air moving at high velocity through a gap smaller than the designed opening - a classic symptom of a leak under pressure. The sound often localizes near a failed joint or a register boot that has separated from the drywall, and it’s a reliable indicator that conditioned air is being wasted.
• Musty or chemical odors when the system runs. Leaks on the return side can pull odors from crawl spaces, attics, or wall cavities into the air stream, while leaks on the supply side can allow condensation that supports microbial growth inside the duct. In Lewisville’s older homes near Central Park, we’ve found that musty smells often trace to decades-old duct tape that has failed and allowed attic air infiltration.

Before

After

Our Duct Repair & Sealing Process - Step by Step

1. 1
   System inspection and pressure assessment. We start with a visual inspection of all accessible ductwork and a static pressure test to quantify how much air the system is losing relative to design specifications. In Lewisville, we typically find that residential systems operate at 0.3-0.6 inches of water column below optimal static pressure due to leakage. The technician records baseline readings and identifies the highest-priority repair points.
2. 2
   Written scope and price delivered before work begins. Based on the inspection findings, we prepare a written description of every repair needed, with a single flat price for the complete scope. Haven Standard Clause 1 requires this price to be accepted in writing before any panel comes off or any sealant is opened. There is no “call for a quote” - the number is on the page, and it does not change unless the homeowner requests additional work.
3. 3
   Photo documentation of existing conditions. Before touching anything, we photograph every duct run, joint, and register connection that will be addressed. These photos become the “before” half of the Documented Photo Record, and they often reveal conditions the homeowner has never seen - collapsed flex duct, rusted metal seams, or builder shortcuts that have hidden in the attic for fifteen years.
4. 4
   Repair and sealing execution. Our crew performs the agreed scope using professional-grade equipment and materials - mastic from recognized manufacturers, metal sleeves and straps for flex duct repairs, and replacement insulation where needed. Technicians work under Haven Standard Clause 3: Verified Crews, meaning every person in your home has passed a background check and is identified by name before arrival.
5. 5
   Verification, photo record delivery, and written warranty. After repairs are complete, we re-test system pressure to confirm improvement, photograph every completed repair, and deliver the full photo record to the homeowner as part of the standard job documentation. The 365-Day Done Right Promise is activated in writing: if any sealed joint fails, any repaired duct separates, or any covered leak reopens within one year, we return and make it right at no charge.

How Much Does Duct Repair & Sealing Cost in Lewisville?

Duct Repair & Sealing Near Lewisville - Our Service Area

CleanRun serves homeowners throughout the Lewisville-Flower Mound corridor and surrounding communities, including Carrollton, Flower Mound, Grapevine, Little Elm, Southlake, Frisco, Irving, Plano, Denton, Richardson, and Allen. Most Lewisville appointments are scheduled within 2-4 business days, and our technicians arrive in marked vehicles with the equipment roster - including Rotobrush and Nikro systems - needed to complete repairs in a single visit. Whether you’re in the established neighborhoods near Lewisville High School or newer construction around the Medical City Lewisville area, the process is the same: written price first, documented work, accountable warranty.

Frequently Asked Questions - Duct Repair & Sealing in Lewisville

Schedule Your Duct Repair & Sealing Service in Lewisville Today

Call (940) 240-8552 to schedule a free estimate. A live person answers every call, and you’ll receive a written flat price before any work begins - no exceptions, no surprises. Every repair is documented with before-and-after photos and backed by the 365-Day Done Right Promise. We’re independently owned and operated under the Haven Standard, serving Lewisville homeowners since 2013.

Written by Tomas Reyes, Owner at CleanRun Duct Repair & Cleaning, serving Lewisville since 2013.