
Ductwork Repair & Sealing
DUCTWORK REPAIR & SEALING IN NORTH LOUISIANA
Hot rooms, cold rooms, and high bills usually start in the ducts. We find, seal, and repair leaky, crushed, and undersized ductwork so every room gets its share of air — flat-rate quote before we start.
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3,569 reviews · 2 profiles
24/7 Emergency
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Licensed & insured
LA Master Plumber #1874
North Louisiana
Ruston to Monroe
Flat-rate pricing
Quoted before we start
Overview
The duct system your comfort depends on
Your furnace and AC only matter if the air they make actually reaches the room. In a lot of North Louisiana homes, up to a quarter of that conditioned air leaks out of the ducts before it ever hits a register — into the attic, the crawlspace, or the wall cavities. You pay to heat and cool it anyway. Mark Johnson & Sons finds those leaks, seals them, and repairs the runs that are crushed, disconnected, or too small to do their job.
The tech who shows up is on our payroll — no subcontractors — and every quote is flat-rate, given before we touch a tool. We handle both sides of the system: heating airflow in winter and cooling airflow in the humid summer, because the same leaky duct that lets your heat escape in January is dumping cold, dehumidified air into the attic in July.
What we service
- Supply and return runs — sheet-metal trunk lines, round pipe, and flex duct, from the air handler to every register
- Duct sealing — mastic and UL-181 metal tape on accessible joints, boots, and plenum connections, not the cloth "duck tape" that dries out and falls off in a few seasons
- Crushed, sagging, and disconnected runs — reconnected, re-supported, and re-strapped so they stop drooping and pinching off airflow
- Undersized and starved rooms — new or rerouted runs and correctly sized returns so a back bedroom finally keeps up
- Damper and register balancing — evening out room-to-room airflow across the house
Repair vs. replace
Most homes we see just need sealing and a handful of targeted repairs — a full duct replacement is the exception, not the rule. We only call for a whole-system replacement when the ducts are badly undersized for the equipment, collapsing, or so deteriorated that patching them isn't cost-effective. On older North Louisiana homes with brittle flex or a duct system that was never sized right, a load-calculated redesign can be the honest answer — and we'll show you the flat-rate math on both before you decide.
What Mark Johnson & Sons does differently
We don't sell you a new furnace to fix a few leaky joints. We inspect the runs through the attic and crawlspace, measure airflow at the registers that bother you, and quote only the work that actually fixes the comfort problem — then verify the fix by re-checking airflow before we leave. Ask about our service savings agreement plans — from $189/year, covering a Spring AC and Fall heating tune-up plus an annual plumbing check-up, and service members get 15% off any duct repair we find plus front-of-line scheduling.
Free quote
Get a straight quote on your ductwork
Tell us which rooms never feel right and what your bills have been doing. We'll inspect the system, show you what we find, and quote flat-rate before any work starts.
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Duct sealing service
Standard pricing. Must mention at booking. One offer per household.
Expires 12/31/2026
FREE
Duct inspection with any HVAC repair
Diagnostic waived when you have us do the work.
Expires 12/31/2026
15% OFF
Duct repairs for service members
Service savings agreement required. Not combinable with other offers.
Expires 12/31/2026
Mention coupon when booking. One offer per household.
Warning signs
Signs Your Ductwork Needs Attention
Duct problems rarely announce themselves — they show up as comfort and bill complaints. If any of these sound familiar, the ducts are worth a look.
One or two rooms never get warm in winter or cool in summer
Heating and cooling bills keep climbing with no change in habits
Weak or no airflow from certain registers
The system runs constantly but the house never feels comfortable
Rooms that are dusty no matter how often you clean
Whistling, rattling, or banging sounds in the ducts when the system kicks on
Visible sagging, disconnected, or crushed duct in the attic or crawlspace
Rooms feel muggy or humid even when the AC is running
A musty or dusty smell when the system first cycles on

Even comfort
One room always wrong? The ducts are usually why.
Sealing leaks and fixing crushed runs is the cheapest comfort upgrade in the house — evens out the hot and cold rooms and cuts what you spend heating and cooling air that used to leak away.
Air lost to leaks
20%+
Across Ruston, Monroe, West Monroe, and North Louisiana.
The Process
How a Ductwork Service Call Goes

On the truck
Professional tools, parts, and diagnostics — every call.
Comfort walk-through
We start with the rooms that bother you. Which are too hot, too cold, or dead-air? That maps us straight to the runs worth inspecting first.
Inspection & airflow check
We trace the ducts through the attic and crawlspace, check for leaks, crushed sections, and disconnected joints, and measure airflow at the problem registers. You see photos of what we find.
Flat-rate quote
You get a written price to seal, repair, reroute, or replace only what needs it — no upsell to replace a whole system when a few joints are the issue.
Seal & repair
We seal joints with mastic and metal tape, reconnect and re-support sagging runs, replace crushed or undersized sections, and add or reroute runs to balance starved rooms.
Balance & verify
We re-check airflow at the registers, adjust dampers to even out the house, and confirm the rooms that used to suffer are actually getting air before we leave.
Pricing
How We Price Ductwork in North Louisiana
Flat-rate, quoted before we start. Most homes need sealing and a few repairs, not a full replacement. Service members get 15% off repairs.
Flat rate, quoted before we start
You get the full price for the job up front — not an hourly meter you watch climb. You approve it before a tool comes out of the truck.
The quote is the price
It doesn't move once work begins. If something unexpected turns up behind a wall or under a slab, we stop and talk it through with you before going further.
Service members save 15% on every repair
Service savings agreements start at $189 a year and take 15% off all plumbing, heating, and cooling repairs, with priority scheduling on every call. The Premium Service Savings Agreement Plan adds same-day service and drops after-hours charges entirely.
Financing available
Bigger jobs — a system replacement, a repipe, a sewer line — can be financed through GoodLeap. Apply online in a few minutes.
Every job is priced for your home and what it actually needs — tell us what's going on and we'll get you a firm number, free and with no obligation.
Service Savings Agreement Plans
Two plans. Whole-home peace of mind.
From $189 a year, service members get 15% off every plumbing, heating, and cooling repair, two complete HVAC tune-ups, a free plumbing and drain check-up, and priority scheduling on every call.
- 15% off repairs
- Priority scheduling
- 2 HVAC tune-ups/yr
- After-hours discounts
- $25 savings certificate
- Guaranteed flat-rate
Service Savings Agreement Plan
$189/year
Everything it takes to keep the house maintained and your repairs discounted.
Each additional HVAC unit is $89/year
Premium Service Savings Agreement Plan
$389/year
Everything in the Service Savings Agreement Plan, plus no after-hours charges, no travel fees, and same-day service.
Each additional HVAC unit is $89/year
Questions? (318) 319-0220
1-year term · does not auto-renew
FAQ
Ductwork Repair & Sealing FAQs
How do I know if my ductwork is leaking?
The clearest signs are rooms that never feel right, climbing heating and cooling bills, weak airflow at some registers, and a system that runs nonstop without getting comfortable. On a North Louisiana home with attic or crawlspace ducts, leaks are common — we can inspect and show you exactly where the air is escaping.
Does duct sealing really lower my bills?
Yes. When up to 20–30% of your conditioned air leaks into the attic or crawlspace before reaching a room, you're paying to heat and cool space you don't live in. Sealing the accessible joints and connections keeps that air in the ducts, so the system runs shorter cycles to hit the same temperature.
Do leaky ducts affect both heating and cooling?
Absolutely — it's the same duct system year-round. A leak that lets warm air escape into the attic in a North Louisiana winter is dumping cold, dehumidified air up there all summer. Fixing the ducts helps comfort and bills in both seasons.
Should I repair the ducts or replace them?
Most homes just need sealing and a few targeted repairs — replacing a whole duct system is the exception, not the rule. We only recommend full replacement when the ducts are badly undersized, collapsing, or so deteriorated that patching them isn't cost-effective. You get honest flat-rate math on both.
How much does duct sealing or repair cost in North Louisiana?
Sealing an accessible system is the lightest job, with individual section repairs and adding or rerouting a run close behind. A full whole-home replacement is a much bigger project. The diagnostic is a flat fee and gets waived when you have us do the work.
Can you fix a room that's always hotter or colder than the rest?
Usually, yes. A room that never keeps up is often on a starved, undersized, or disconnected run, or the system just isn't balanced. We check airflow at that register, seal or repair the run feeding it, add or reroute duct if needed, and adjust dampers to even the house out.
What kind of tape or sealant do you use on ducts?
Mastic and UL-181-rated metal foil tape — not the cloth 'duct tape' from the hardware store, which dries out, loses its stick, and falls off within a couple of seasons in a hot attic. Mastic stays flexible and airtight for the life of the duct, which is why code and manufacturers call for it.
How long does duct sealing and repair take?
Most sealing and targeted-repair jobs wrap in a day, often a single visit. A larger reroute, added return, or partial replacement may run longer depending on attic access and how the runs are laid out. We give you a realistic timeline with the flat-rate quote before any work starts.
Do I need a permit to have ductwork replaced?
A repair or sealing job typically doesn't, but a full duct replacement or major modification usually does in Ruston, Monroe, West Monroe, and the surrounding parishes. When a permit is required we pull it, schedule the inspection, and fold the fee into the flat-rate quote — you don't chase paperwork.
Do you check ductwork during a maintenance visit?
We give the accessible ducts a look on every tune-up, and our $189/year Service Savings Agreement Plan includes a Spring AC and Fall heating tune-up plus an annual plumbing check-up. If we spot leaks or damage during a visit, service members get 15% off the repair and priority scheduling.
Can leaky ducts make my house dustier or worsen allergies?
Yes. Return-side leaks pull dust, insulation fibers, and attic or crawlspace air straight into the system and blow it around the house — a real problem during North Louisiana's long pollen seasons. Sealing the returns and boots cuts the dust load and lets the filter actually do its job.
Related services
Related Heating Services
These come up often on the same call as ductwork.

Furnace & Heating Maintenance
Complete seasonal tune-up — safety checks, cleaning, and airflow inspection.

Heat Pump Service
Repair, replacement, and tune-ups for year-round comfort in mild winters.

Thermostat Installation
Smart and programmable thermostat setup — better comfort control, lower bills.
Available Around the Clock
Emergency?
We answer 24/7.
Burst pipe, water heater out, sewer backup? Real plumbers pick up — no answering machines. Mark Johnson & Sons Plumbing serves North Louisiana any time, day or night.
LA Master Plumbing #1874 · Backflow Cert #28131 · Master Natural Gas Fitter #LMNGF9062 · State Contractors #35794