InstaBidsFor homeowners
Types of ductwork: which duct material fits your home?
Choose Sheet metal (galvanized steel) for homes in jurisdictions where it is required; Fiberglass duct board for plenums, trunks and junction boxes; Flexible duct (flex duct) for runs with several bends and turns, without the need for additional fittings or connections.
The right choice depends on local requirements, the part of the system the duct serves, and how many bends and turns the run needs.
| Type | Best for | Main advantages | Main drawbacks |
|---|---|---|---|
| Sheet metal (galvanized steel) | homes in jurisdictions where it is required | DOE Building America guide (2011): a wide array of sheet metal fittings connect sections of duct (elbows, transitions, takeoffs, reducers) | DOE Building America guide (2011): if seams, gaps and connections are not sealed before insulation, substantial leakage can result |
| Fiberglass duct board | plenums, trunks and junction boxes | DOE Building America guide (2011): made with fiberglass insulation to provide some level of thermal resistance; DOE Building America guide (2011): the outside typically has a fiber-reinforced foil facing that acts as a vapor barrier; HUD Rehab Guide (1999): quieter than sheet metal ducts because it attenuates blower noise that can carry through the duct system | DOE Building America guide (2011): when duct board trunks are sealed with foil tapes during installation, these tapes do not necessarily maintain their integrity over time |
| Flexible duct (flex duct) | runs with several bends and turns, without the need for additional fittings or connections | DOE Building America guide (2011): insulated flex duct is made with fiberglass insulation to provide some level of thermal resistance; DOE Building America guide (2011): with fewer transitions and fittings, flex duct can be very air-tight | DOE Building America guide (2011): less durable than other duct materials; it can be twisted, compressed or torn, resulting in leaks; DOE Building America guide (2011): resists air flow more, especially when the duct is not fully extended; ENERGY STAR lists tangled or kinked flexible ducts among the signs of poorly performing ducts |
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Post your job on InstaBids, and contractors can bid in writing on one written scope.
- Describe it onceBy chat, or through your own AI assistant, and add photos.
- Post it and send itContractors bid in writing on that scope.
- Compare line by lineEvery quote is written against the same scope.
- You chooseContact details stay hidden until you pick and they confirm.
For your AI assistant
MCP connector · REST API · plain HTMLHand any of these to your assistant and it can help you write this job's request; you send the request yourself. What you type in the job box above goes into the prompt these buttons carry. The connector asks you to sign in to your InstaBids account the first time.
- MCP connector URL
https://instabids.ai/api/agent/mcp - Agent API (OpenAPI)
https://instabids.ai/openapi.json - Start-request link
https://instabids.ai/intake?trade=hvac&from=options-ductwork&utm_source=us&utm_medium=page&utm_campaign=options&page_type=options#job=ductwork%20installation%20or%20replacement - Prompt for any AI, with your job
- ChatGPTOpens with the prompt
- ClaudeOpens with the prompt
- GrokOpens with the prompt
- GeminiCopies the prompt, then opens
Every page is plain HTML. Steps for every assistant: add to your assistant.
| Priority | Choose |
|---|---|
| your jurisdiction requires galvanized steel duct (DOE Building America, 2011) | Sheet metal (galvanized steel) |
| a plenum, trunk or junction box (DOE Building America, 2011) | Fiberglass duct board |
| a run with several bends and turns and no extra fittings (DOE Building America, 2011) | Flexible duct (flex duct) |
Get written bids
Contractors who take part bid on one written scope card, so nobody visits before you see any prices.
The contractor you pick may visit once before settling the final price against the percentage the bid stated.
Contractors in your trade see the scope card and your 5-digit ZIP code.
Contact details stay hidden until the homeowner picks a contractor and they confirm the connection.
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Sources for the facts on this page
- U.S. Department of Energy, Building America, Measure Guideline: Sealing and Insulating Ducts in Existing Homes (December 2011), government, read 22 October 2026.
- U.S. Department of Housing and Urban Development, The Rehab Guide, Volume 8: HVAC/Plumbing (1999), government, read 22 October 2026.
- ENERGY STAR (U.S. EPA), Duct Sealing, government, read 22 October 2026.