🎯Quick Answer: What Is Fabric Duct?
Fabric duct is ductwork made from engineered textile instead of sheet metal. The name covers two products: fabric air dispersion duct (a suspended polyester "duct sock" that transports and diffuses supply air, $4–$20/ft depending on diameter), and fabric duct hose (a wire-reinforced nylon, canvas, neoprene, or silicone hose for portable ventilation and extraction, $8–$45/ft). Both weigh a fraction of metal, install without sheet-metal labor, and can be washed. Neither is a drop-in replacement for metal in high-pressure trunk applications above roughly 3 in. w.c.
Search fabric duct and you get two entirely different answers depending on who wrote the page. Commercial HVAC sites show you a long polyester tube hanging from a gymnasium ceiling. Industrial supply sites show you a wire-reinforced hose clamped to a portable blower. Both are correct. Both are called fabric duct. And buyers regularly order the wrong one.
We manufacture flexible ducting at a 46,000 sq ft facility in Brookshire, TX, and the single most common specification error we see on flexible fabric duct inquiries is a mismatch between the two families — someone specs a lightweight dispersion fabric for a negative-pressure extraction run, and it collapses on the first startup. So this guide starts with the split, then goes deep on materials, permeability, sizing, cost, and code for each.
The Two Products Called "Fabric Duct"
Before you compare materials or pricing, decide which family you are buying. The distinction is not cosmetic — the two products have opposite pressure behavior.
Fabric air dispersion duct (duct sock, textile duct, fabric ductwork) is an unreinforced or lightly reinforced textile tube hung from cable or track. It is a positive-pressure-only device. Internal pressure is what gives it its round shape; the moment pressure drops, it deflates. It replaces both the trunk duct and the diffusers in one component, which is why the labor savings are so large.
Fabric duct hose is a coated fabric wall bonded over a spring-steel wire helix. The helix is what holds the shape, so the hose works under positive or negative pressure, handles being dragged across a job site, and survives 250°F to 500°F exhaust depending on the coating. It replaces rigid pipe on temporary, portable, or vibration-isolated runs.
| Attribute | Fabric Air Dispersion Duct | Fabric Duct Hose |
|---|---|---|
| Also called | Duct sock, textile duct, fabric ductwork | Fabric hose, blower hose, ventilation hose |
| Shape held by | Internal air pressure | Steel wire helix |
| Pressure | Positive only (0.5–3.0 in. w.c.) | Positive or negative (to 12 in. w.c. neg.) |
| Typical diameter | 8"–60" | 2"–24" |
| Temperature limit | Up to ~180°F | Up to 500°F (silicone/fiberglass) |
| Delivers air via | Whole surface, orifices, nozzles, linear vents | Open end only |
| Best for | Permanent commercial supply air | Portable ventilation, extraction, spot cooling |
| 2026 cost/ft | $4–$20 | $8–$45 |
⚠️The Most Expensive Mistake
Never put fabric air dispersion duct on the suction side of a fan. It has no helix and will collapse flat within seconds of startup, and the fabric will be creased permanently. If your run sees any negative pressure — return air, dust collection, fume extraction, filter downstream — you need a wire-reinforced hose, not a dispersion sock.
Fabric Duct Materials Compared
"Fabric duct material" is the second-most-searched thing about this product category, and most manufacturer pages answer it with a single word: polyester. That is true for air dispersion, but incomplete. Here is the full material set we actually run, with the specs that determine whether a fabric survives your application.
| Material | Weight | Temp Range | Best Use |
|---|---|---|---|
| Permeable woven polyester | 4.5–6 oz/yd² | -20°F to 180°F | Low-temp supply air, condensation-prone rooms |
| Non-permeable coated polyester | 6–9 oz/yd² | -20°F to 180°F | Long throw, high-bay, directional dispersion |
| PVC-coated polyester | 10–16 oz/yd² | -20°F to 180°F | Washdown areas, outdoor, abrasion resistance |
| Coated nylon fabric | 8–12 oz/yd² | -40°F to 250°F | Lightweight portable hose, high flex fatigue life |
| Neoprene-coated fabric | 14–22 oz/yd² | -40°F to 250°F | Oil mist, chemical exposure, engine exhaust intake |
| Silicone-coated fiberglass | 18–30 oz/yd² | -70°F to 500°F | High-temp exhaust, kiln, foundry, welding fume |
| Cotton canvas (untreated) | 10–14 oz/yd² | -20°F to 180°F | Low-cost ambient air movement, vibration connectors |
Two numbers do most of the work here. Fabric weight in oz/yd² predicts abrasion life and how well the duct holds a shape under load — a 4.5 oz/yd² dispersion fabric is fine hanging in a clean office ceiling and will shred in six months in a grain facility. Continuous temperature rating is where people get burned, literally: a PVC-coated fabric rated to 180°F put on a 220°F exhaust will soften, the coating will delaminate from the scrim, and the hose fails in weeks.
Also check the coating side. Single-side coated fabric costs 15-25% less but exposes the raw scrim to whatever is inside the duct. For anything carrying moisture, oil mist, or particulate, specify double-side coated.
💡Need Help Matching Material to Application?
Send us your air temperature, what is entrained in the airstream (dust, oil mist, solvent, moisture), and whether the run is positive or negative pressure. That is enough for us to name the right fabric. Contact USFlexDuct and we will spec it against our stock inventory in Brookshire, TX.
Permeable vs Non-Permeable: How Fabric Duct Actually Delivers Air
This is the mechanism that makes fabric air dispersion duct different from every other duct type, and it is the part competitor guides skip. Air leaves a fabric duct in one of four ways, and you usually combine two of them in the same run.
1. Surface permeation. The weave itself passes air at roughly 0.5–5 CFM per square foot at 0.5 in. w.c. The discharge velocity at the fabric face is under 50 FPM — essentially draft-free. This is the only method that keeps the fabric surface near room temperature, which is why permeable fabric is the standard answer for supply air below 55°F: the fabric never gets cold enough to condense.
2. Laser-cut orifices. Rows of small holes, typically 4–20 mm, cut at specified clock positions (4 and 8 o'clock is the common pattern for ceiling-hung duct). Throw distance runs 5–25 ft. Orifice sizing and spacing are engineered per zone so the duct discharges evenly along its length instead of dumping most of the air at the far end.
3. Nozzles. Injection-molded or fabric nozzles for long throw — 30–100 ft. Used in high-bay warehouses, arenas, and any space where the duct is 25+ ft above the occupied zone.
4. Linear vents. Continuous mesh strips sewn along the duct. Medium throw with a wide fan pattern, common in food processing and retail where you want a curtain of air rather than jets.
| Method | Throw | Face Velocity | Condensation Risk |
|---|---|---|---|
| Surface permeation | 0–3 ft | < 50 FPM | Lowest — fabric stays warm |
| Laser orifices | 5–25 ft | 800–1,500 FPM | Moderate on non-permeable fabric |
| Nozzles | 30–100 ft | 1,500–2,500 FPM | Higher — needs 55°F+ supply or dry space |
| Linear vents | 8–30 ft | 400–900 FPM | Moderate |
The practical rule: if your supply air is below 55°F and the room runs above 55% RH, use permeable fabric. If you need to throw air more than 25 ft, you need non-permeable fabric with nozzles, and you need to verify the dew point math before you sign off — a non-permeable fabric carrying 48°F air in a 70% RH warehouse will sweat and drip on whatever is below it.
Fabric Duct Sizing: CFM, Velocity & Static Pressure
Fabric duct is sized at a lower velocity than metal. Metal commercial trunk duct is commonly designed at 1,800–3,000 FPM; fabric air dispersion runs at 1,200–2,400 FPM inlet velocity. Push past 2,400 FPM and you get audible rush noise and accelerated fabric wear at the seams.
| Diameter | Area (ft²) | CFM @ 1,200 FPM | CFM @ 2,400 FPM |
|---|---|---|---|
| 8" | 0.35 | 420 | 840 |
| 10" | 0.55 | 660 | 1,310 |
| 12" | 0.79 | 940 | 1,890 |
| 16" | 1.40 | 1,680 | 3,350 |
| 18" | 1.77 | 2,120 | 4,240 |
| 24" | 3.14 | 3,770 | 7,540 |
| 32" | 5.59 | 6,700 | 13,410 |
| 40" | 8.73 | 10,470 | 20,950 |
Three sizing constraints that are specific to fabric and do not appear in a standard metal duct calculation:
Minimum inlet static pressure. You need at least 0.5 in. w.c. at the duct inlet to inflate the fabric to a true circle. Below that, the duct sags into an oval and the discharge pattern goes uneven. Fabric systems are usually designed for 0.5–1.5 in. w.c., with 3.0 in. w.c. as a practical upper limit before seam stress becomes a concern.
Length-to-diameter ratio. Keep total run length under roughly 100× the diameter for a single inlet. A 12-inch duct fed from one end should not exceed about 100 ft; beyond that, static pressure decays and the far end starves. Longer runs need a mid-point feed or a tapered (reducing) duct profile.
Inlet transition. The connection from rigid metal to fabric needs a straight section of at least 3 duct diameters upstream. Fabric duct hung directly off a fan discharge or a tight elbow will see swirl, and the whole downstream discharge pattern will be skewed to one side. If you are sizing the upstream metal portion, our HVAC duct sizing guide and flex duct CFM chart cover the velocity and friction math.
Fabric Duct Cost Per Linear Foot (2026)
Published fabric duct pricing is scarce because most systems are quoted as engineered projects. Here are the 2026 ranges we see in the North American market, broken into material and installed cost so you can build a real estimate.
| Diameter | Fabric Only | + Suspension Hardware | Installed |
|---|---|---|---|
| 4"–8" | $4.00–$8.00 | +$1.50–$2.50 | $6.00–$12.00 |
| 10"–16" | $6.00–$12.00 | +$2.00–$3.00 | $9.00–$16.00 |
| 18"–30" | $12.00–$20.00 | +$2.50–$4.00 | $16.00–$28.00 |
| 32"–60" | $20.00–$38.00 | +$3.50–$6.00 | $26.00–$48.00 |
Cost adders to budget for:
- Antimicrobial treatment: +$2.00–$4.00/ft — required in most food processing and healthcare specs
- Fire-retardant / UL 2518 listed fabric: +$2.00–$6.00/ft over unlisted material
- Custom color match: +$1.00–$3.00/ft, usually with a 300 ft minimum per color
- Engineered nozzle layout (CFD-verified): $800–$3,500 one-time design fee per zone
- Spare fabric set (recommended): full fabric cost — lets you launder without shutting the space down
The headline comparison: an installed 18-inch fabric run at $16–$28/ft against an equivalent insulated spiral metal run with diffusers at roughly $38–$65/ft installed. Fabric wins on first cost by 40–60%, mostly because you delete the diffusers, the flex drops, the hanger straps, and about two-thirds of the sheet-metal labor hours.
Where metal claws it back is service life. Fabric lasts 10–20 years depending on grade; a galvanized spiral system lasts 30–50. Budget one fabric replacement inside a 25-year building lifecycle. We break the full lifecycle math down in our fabric duct vs metal duct comparison, which includes a 10-year total cost of ownership table.
Inside the Factory: How Fabric Duct Is Built
Most fabric duct content is written by marketers. Here is what the product actually is on a production floor, because the construction details are what separate a five-year duct from a fifteen-year duct.
The scrim decides everything. Under the coating is a woven base cloth — the scrim — typically a 500–1,000 denier polyester in a plain or basket weave. Thread count and denier set tensile strength and tear propagation. A cheap fabric duct is almost always a cheap scrim with a normal-looking coating on top. Ask for the grab tensile strength (ASTM D5034) and the trapezoid tear (ASTM D5587), not just the finished weight.
Seams are the failure point. Three constructions, in ascending order of durability: sewn only (cheapest, leaks at the needle holes, fine for permeable fabric where leakage is the point), sewn and taped, and RF-welded or hot-air-welded (no needle penetrations at all — this is what you want on coated fabric, and it is what allows the duct to hold 3 in. w.c. without weeping at the seam).
Zippers matter more than they should. Fabric duct is shipped in 10–20 ft sections joined by heavy-gauge coil zippers. A #10 zipper is the practical minimum for anything over 16 inch diameter; #8 zippers on large duct fail at the slider under pressure cycling. Specify the zipper gauge in your PO — it is the single cheapest durability upgrade available.
Orifice cutting. Laser cutting seals the edge of the hole as it cuts, so the orifice does not fray. Die-punched orifices are cheaper and will progressively enlarge over a few thousand hours of operation, which quietly detunes your whole air distribution. If a supplier will not tell you which method they use, assume die.
On the hose side, our industrial fabric hose lines run a spring-steel helix encapsulated between two fabric plies, with the wall built up on a mandrel and cured. The number of plies and the helix pitch set the crush rating and the minimum bend radius — a 1× diameter bend radius means roughly a 50% tighter helix pitch than a 2× product, and about 30% more material per foot.
Codes & Listings: UL 2518, NFPA 90A, ASTM E84
Fabric duct gets rejected by plan reviewers more often than metal, purely because the documentation is unfamiliar. Here is what you need in the submittal.
UL 2518 — Air Dispersion Systems. This is the listing standard specifically written for fabric air dispersion duct. If your project is a commercial HVAC system under the International Mechanical Code, a UL 2518 listing is the cleanest path to approval. Get the UL file number, not a "tested to" claim.
ASTM E84 (also UL 723) — Surface Burning Characteristics. NFPA 90A requires duct materials in air distribution systems to have a flame spread index of 25 or less and a smoke developed index of 50 or less — the "25/50" rating. Every serious fabric duct product carries an E84 report; ask for the actual report, since some fabrics pass flame spread but exceed 50 on smoke.
NFPA 90A §5.3 also governs where duct penetrates fire-rated assemblies. Fabric duct generally is not run through fire barriers — you transition to metal at the barrier and fire-damper it there.
Antimicrobial claims. If a fabric is marketed as antimicrobial, it needs an EPA registration for the treated-article claim. In food plants, cross-check against your USDA/FSIS or SQF program requirements rather than the fabric datasheet alone.
Static. Standard polyester dispersion fabric is insulative (above 10¹¹ ohms) and will build charge. In any space with combustible dust, specify a static-dissipative fabric and bond the suspension cable to ground — see our anti-static duct guide for the NFPA 652 requirements and resistance targets.
Where Fabric Duct Wins — and Where It Fails
We sell both fabric and metal-compatible products, so here is the honest split.
| Application | Fabric? | Why |
|---|---|---|
| Gyms, arenas, natatoriums | Yes | Corrosion immunity, no drafts on occupants, light structural load |
| Food processing / cold storage | Yes | Launderable, no condensate drip with permeable fabric, antimicrobial options |
| Warehouse / high-bay | Yes | Nozzles throw 100 ft; retrofit onto existing roof structure without steel |
| Indoor agriculture / grow rooms | Yes | Even canopy temperature; no hot/cold stripes from point diffusers |
| Restaurants / open retail | Maybe | Works, but grease-laden air is disqualifying; check the aesthetic with the architect |
| Return air / exhaust runs | No | Negative pressure collapses dispersion fabric — use metal or reinforced hose |
| Kitchen grease exhaust | No | NFPA 96 requires welded liquid-tight steel |
| Concealed / above ceiling | No | Needs clearance to inflate and access to unzip and launder |
| High-pressure trunk (>3 in. w.c.) | No | Seam stress and noise; spiral metal is the correct product |
If your project falls in the "No" rows, look at wire-reinforced flexible duct or insulated flex duct instead — both handle negative pressure and concealed installation.
Fabric Duct for Grow Rooms
Indoor agriculture is the fastest-growing application we quote, and it is worth its own section because the failure modes are specific.
The problem fabric solves. A metal duct with six ceiling diffusers over a 40 ft canopy creates six cold zones and five warm zones. Measured canopy temperature spread of 6–9°F is normal in that layout. A permeable or fine-orifice fabric duct running the length of the room discharges at under 50 FPM across its whole surface and typically holds the spread under 2°F. Consistent canopy temperature means consistent VPD, which means consistent growth rates across the room rather than across a bench.
The humidity trap. A flower room at 65–70% RH with 55°F supply air will condense on non-permeable fabric. Use a permeable fabric so the surface stays near room temperature, or raise the supply air temperature and accept a longer runtime. This is the mistake we see most often on grow-room fabric duct retrofits.
Specify antimicrobial. Warm, humid, organic-rich air is the ideal environment for surface growth. An EPA-registered antimicrobial treatment costs $2–$4/ft and is not optional in a flower room.
Supply side only. Fabric dispersion duct belongs downstream of the fan on the supply side. Your carbon filter run, exhaust, and any negative-pressure section needs insulated flexible duct or a reinforced hose. Our grow room ventilation duct guide covers the full intake/exhaust layout, CFM sizing per light, and filter placement.
💡Grow Room Sizing Shortcut
Target 1 CFM per watt of lighting load for air movement, then size the fabric duct diameter to keep inlet velocity in the 1,200–1,800 FPM band. A 20,000 W room needs roughly 20,000 CFM of circulation, which puts you at a 40-inch fabric duct — or two 32-inch runs, which is usually the better layout for a rectangular room.
Industrial Fabric Duct Hose: Nylon, Canvas & Silicone
The other half of "fabric duct" — wire-reinforced fabric hose — is what you need when the run is temporary, portable, hot, or under suction. These are stock items at our Brookshire warehouse.
| Hose Type | Temp | Diameters | Typical Use |
|---|---|---|---|
| Nylon fabric duct hose | -40°F to 250°F | 2"–20" | Portable ventilation, confined space blowers |
| Canvas fabric duct hose | -20°F to 180°F | 3"–24" | Low-cost ambient air, vibration connectors |
| Silicone fabric duct hose | -70°F to 500°F | 2"–16" | Hot exhaust, welding fume, kiln and foundry |
| PU flexible hose | -40°F to 200°F | 2"–12" | Abrasive dust and chip collection |
Selection comes down to three questions: what temperature, is anything abrasive in the airstream, and how tight is the bend radius. Nylon is the default for general portable air; step to silicone the moment you exceed 250°F; step to polyurethane when you are moving wood chips, metal shavings, or anything else that will sand through a fabric wall. Full material-by-material breakdown is in our nylon duct hose guide and dust collection duct guide.
Suspension, Installation & Laundering
Suspension. Three systems, in ascending cost: single galvanized aircraft cable through sewn loops (cheapest, allows the duct to roll slightly, fine for small diameters); dual cable (holds orientation so orifices stay at their design clock position — required for anything with engineered orifices); and aluminum H-track with sliders (cleanest appearance, easiest to remove for laundering, roughly 2× the cable cost). Support spacing is typically 5–10 ft depending on diameter.
Installation time. A two-person crew hangs 100–200 linear feet of fabric duct per day including cable and end caps. The same run in insulated spiral metal with diffusers takes 3–5 crew-days. That labor delta is the real reason fabric wins on installed cost, and it is why fabric is popular on fast-track tenant improvements.
Startup. Inflate the duct with the system running before final cable tensioning. Fabric relaxes about 1–2% under pressure; tension it flat and you will get a sagging belly on the first run day.
Laundering. Unzip sections, wash cold below 105°F, no bleach, no fabric softener (softener plugs the pores on permeable fabric and permanently changes the airflow), air dry only. Rotate a spare set if downtime is expensive. Expect 20–30 wash cycles from quality polyester before the permeability spec drifts out of range.
What to Send a Manufacturer for a Quote
Fabric duct quotes bounce back with questions more than any other product we sell. Send these eight items and you will get a firm number on the first pass:
- Total CFM per run, and the number of runs
- Supply air temperature and the room design temperature and RH (this decides permeable vs non-permeable)
- Available static pressure at the fabric inlet, in inches w.c.
- Mounting height to the duct centerline and the ceiling height (this decides throw method)
- Run length and layout — a marked-up reflected ceiling plan is ideal
- Inlet size and shape, and whether the transition is round or rectangular
- Environment: food, pharma, agriculture, pool, general commercial — this drives antimicrobial and coating requirements
- Required listings: UL 2518, ASTM E84 25/50, any owner-specific spec section
For fabric duct hose, it is simpler: diameter, length, air temperature, what is in the airstream, positive or negative pressure, and required bend radius.
🎯Manufacturer Recommendation
If you are distributing conditioned supply air in an open, exposed, positive-pressure space — fabric air dispersion duct is the better product, and the 40–60% installed cost saving is real. If any part of the run is under suction, concealed, above 180°F, or carrying grease or heavy particulate, use wire-reinforced duct or hose. Most real projects use both: fabric on the supply side, reinforced flex or hose everywhere else.
Frequently Asked Questions
Frequently Asked Questions
What is fabric duct?
How much does fabric duct cost per linear foot?
What material is fabric duct made of?
Is fabric duct code approved for HVAC?
How do you size fabric duct?
Can fabric duct be used in a grow room?
How often does fabric duct need cleaning?
What is the minimum order quantity for custom fabric duct?
Related Guides
- Fabric Duct vs Metal Duct: 12-Dimension Comparison & 10-Year TCO
- Grow Room Ventilation Duct: Sizing, Materials & Setup
- Nylon Duct Hose Guide: Types, Sizes & Applications
- HVAC Duct Sizing Guide: CFM, Velocity & Friction Rate
- Anti-Static Duct Guide: Conductive Materials & NFPA 652
- Industrial Flexible Duct: Materials & Selection
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