Fundamentals
Commercial Ductwork Types: How Each One Is Cleaned
The shape and material of your ductwork decide which tools we use, where access doors go and what can be cleaned versus replaced.
3 min read · Reviewed by Gabriel M.
Office HR suite — supply duct source-removal cleaning above the ceiling grid
Why duct type matters for cleaning
Commercial buildings rarely have one kind of duct. A single Atlanta office floor can mix rectangular trunk lines, round branches, spiral risers and flex runouts to each diffuser. Each surface holds debris differently, so a proper scope names the duct types first and the method second.
Rectangular sheet-metal duct
Common on main trunks above ceilings where height is tight. Flat bottoms let dust settle in thick layers and corners trap debris that round brushes miss. We clean these with air whips and contact vacuuming through access doors cut every 20–40 feet, then seal each door airtight.
Round and spiral duct
Round and spiral duct move air efficiently and stay cleaner, but long exposed runs in warehouses, retail and restaurants still load up. Rotary brushes sized to the diameter work well here. Spiral seams are tight, so the main concern is buildup at fittings, dampers and takeoffs.
Flexible duct
Flex runouts feed most ceiling diffusers. The ribbed inner liner tears easily, so aggressive brushing is not used. Lightly soiled flex is cleaned gently; flex that is crushed, torn, wet or moldy should be replaced, and we tell you which runs fall into that group.
Internally lined and duct board systems
Fiberglass-lined duct and duct board absorb sound but also hold moisture and dust. They are cleaned with soft brushes under HEPA negative air, then coated if the surface is sound. Water-damaged or mold-colonized liner is removed, which our IICRC-licensed mold and water crews handle directly.
What a good duct survey records
Before quoting, our walkthrough documents:
- ✓ Duct type and material for each zone
- ✓ Sizes, lengths and number of air handlers and diffusers
- ✓ Access points needed and ceiling height
- ✓ Damaged runs to replace instead of clean
- ✓ Moisture, mold or construction debris
Common questions
- Can all ductwork be cleaned?
- Most sheet-metal duct can. Damaged flex and wet or moldy liner should be replaced rather than cleaned.
- Do access doors damage my ducts?
- No. Doors are sealed airtight after cleaning and make future inspections easier.
- Is spiral duct easier to clean?
- Usually, because smooth round walls hold less debris, but fittings and dampers still need attention.
Keep reading
Talk to a commercial crew, not a call center
Commercial Air Care services commercial facilities across Metro Atlanta with IICRC-certified crews and per-unit photo documentation on every job.