Galvanized or Stainless HVAC Ductwork? Make the Right Choice | Duct2Go
Choosing between galvanized and stainless steel duct affects performance, durability, and cost. Use this guide to match the material to your environment and budget with confidence.
Both galvanized and stainless steel deliver proven results in HVAC systems. Each has distinct strengths, costs, and care needs. Below you will find a clear comparison, practical pros and cons, and selection criteria you can use on your next submittal or takeoff.
Quick Comparison
| Attribute | Galvanized Steel Duct | Stainless Steel Duct |
|---|---|---|
| Corrosion resistance | Zinc coating protects in moderate humidity and typical commercial conditions | Excellent resistance in high humidity, chemical, and coastal environments |
| Cost | Lower upfront cost and strong value | Higher upfront cost that can pay off with longer service life |
| Strength and durability | Good structural integrity for supply, return, and exhaust | Very durable for aggressive or sanitary applications |
| Weight and handling | Heavier than aluminum and lighter than most stainless options | Heavier, may need stronger supports and careful rigging |
| Hygiene and cleanability | Good for general use | Smooth, easy to clean, preferred for food and healthcare |
| Typical uses | General industrial HVAC, warehouses, manufacturing floors | Chemical plants, food processing, pharma, coastal and high humidity spaces |
Galvanized Duct
What is Galvanized Duct
Galvanized duct is carbon steel coated with zinc for rust protection. The zinc layer resists oxidation and helps extend service life in typical indoor environments.
Pros
- Corrosion resistance: Zinc coating protects against rust in moderate humidity and normal temperature swings.
- Cost effective: Lower initial cost compared to stainless steel.
- Strength and durability: Solid structural performance for residential and commercial work.
Cons
- Harsh environments: In coastal or chemical rich conditions the coating can wear down and expose base steel.
- Weight: Heavier than aluminum which can add handling effort in tight spaces.
- Appearance: Less sleek than stainless for exposed architectural runs.
Joining and Sealing
Use flanged or spiral lock seams. Seal with mastic or UL approved foil backed tape. For higher pressure runs use gasketed flanges.
Maintenance Note
Inspect for surface rust in corrosive areas and touch up or replace sections as needed.
Stainless Steel Duct
What is Stainless Steel Duct
Stainless steel is a steel alloy with chromium that forms a passive layer for corrosion resistance. It is the preferred choice where longevity, sanitation, and harsh exposure are critical.
Pros
- Superior corrosion resistance: Performs in high humidity, chemical, or salt exposure.
- Service life: Long lifespan with minimal surface treatment.
- Hygienic and cleanable: Smooth surface supports food and healthcare standards.
Cons
- Higher cost: More expensive up front but can save money over the full lifecycle.
- Weight: Heavier than galvanized and aluminum which may require stronger supports.
- Over spec risk: In mild environments it may not deliver a cost benefit over galvanized.
Joining and Sealing
Use welded or flanged connections. Sanitary clamps are common. Food grade systems often use silicone gaskets.
Maintenance Note
Check for pitting in chloride rich atmospheres. Otherwise requires limited maintenance.
How to Choose for Your Next Project
- Environment: High humidity, chemicals, or salt exposure favor stainless. Neutral indoor conditions make galvanized a strong choice.
- Budget: If cost is the primary driver and exposure is mild, galvanized keeps spend down. For long service life with limited maintenance, stainless can win on lifecycle cost.
- Application: Food, pharma, clean rooms, and coastal sites benefit from stainless. Residential and standard commercial often use galvanized with great results.
- Logistics: Consider weight, lift access, hanger capacity, and shop skill for welding or sanitary work.
- Codes and standards: Follow local code and SMACNA practices. Include NFPA requirements where fire rated assemblies apply.
Total Cost View
| Option | Upfront Cost | Maintenance | Typical Lifespan | Best Fit |
|---|---|---|---|---|
| Galvanized | Lower | Periodic inspection and touch up in corrosive pockets | Long in mild environments | General industrial HVAC and standard commercial projects |
| Stainless | Higher | Low, check for pitting in chloride areas | Very long in aggressive or sanitary environments | Food and healthcare, chemical plants, coastal and high humidity sites |
Value tip: If corrosion or sanitation would force frequent replacement, invest in stainless or proper coatings early. Lifecycle cost often ends up lower.
Order Materials With Confidence
Duct2Go fabricates galvanized and stainless duct systems with shop level precision. Get straight pipe, elbows, reducers, transitions, takeoffs, access doors, flanges, and hardware that fit the first time.