If your exhaust is over 600°F, it's not "just another exhaust outlet." IMC 510.2 forces you into chimney rules with specific thickness, lining, clearances, and termination heights.
Plain English: Plain-English Highlights
510.2 trigger
Exhaust outlets exceeding 600°F (315°C) must be designed as a chimney per Table 510.2 (single-wall metal chimneys).
Minimum wall thickness (all categories) - 0.127 in (No. 10 MSG)
Termination + lining basics (Table 510.2)
High-heat appliances (over 2,000°F)
1. Lining: 4 1/2 in laid on 4 1/2 in bed
2. Termination: 20 ft above roof opening
3. Termination relative to building: 20 ft above any part of building within 50 ft
4. Clearance: per design engineer (must prevent combustibles exceeding 160°F)
Medium-heat appliances (2,000°F max)
1. Lining: up to 18 in dia: 2 1/2 in; over 18 in: 4 1/2 in on 4 1/2 in bed
2. Termination: 10 ft above roof opening
3. Termination relative to building: 10 ft above any part of building within 25 ft
4. Clearance to combustibles: 36 in interior, 24 in exterior
Low-heat appliances (1,000°F normal operation)
1. Lining: none
2. Termination: 3 ft above roof opening
3. Termination relative to building: 2 ft above any part of building within 10 ft
4. Clearance to combustibles: 18 in interior, 6 in exterior
5. Clearance to noncombustibles: up to 18 in dia: 2 in, over 18 in: 4 in
Lining notes
Lining extends bottom to top of outlet (general).
For the noted condition: lining extends 24 in below connector to 24 ft above.
On Plans: Why it matters
Common misses: showing a hot exhaust as "typical duct," missing the termination height criteria, and ignoring the clearance-to-combustibles impacts (which drives routing, roof layout, and supports).
Code Path: Where to show it
M-001: "EXHAUST >600°F SHALL BE DESIGNED AS CHIMNEY PER IMC 510.2 / TABLE 510.2" + identify category (low/medium/high heat).
Roof plan: termination heights + dimension to "parts of building within X ft" as applicable.
Sections/details: clearances to combustibles/noncombustibles and lining requirement.
Check: Do
Call out the temperature basis and which Table 510.2 row applies.
Dimension termination heights on the roof plan (don't make plan reviewer guess).
Review Risk: Don't
Don't route >600°F exhaust like standard ductwork through tight combustible spaces.
Don't omit the "within 10/25/50 ft" termination check.
Field Tip: Field tip
Use the quick "600°F → CHIMNEY" check:
1. Confirm exhaust temperature >600°F.
2. Select low / medium / high heat row.
3. On the roof plan, note A) ft above roof opening and B) ft above any part of building within X ft.
4. Verify clearances won't force a reroute late.
Comment "IMC510-P5" if you want a paste-ready M-001 chimney note + a roof plan dimensioning checklist.
Masterbuild QA Lens
Exhaust systems need a source-to-discharge story. Identify what is being captured, how it is captured, how it is routed, where it terminates, and what interlocks or separations protect the building.
Drawing / Submittal Check
Verify source classification, hood or pickup point, duct material, route, cleanouts or access, fan selection, discharge location, make-up air, controls, and required coordination with fire protection or alarms.
Common Review Risk
The expensive miss is treating all exhaust the same. Grease, dryer, dust, hazardous, smoke control, battery, and specialty exhaust systems carry different proof requirements.
When To Escalate
Escalate when exhaust involves grease, hazardous materials, combustible dust, battery charging, smoke control, rated shafts, energy recovery, or any discharge that can re-enter the building.
Duct System Coordination
For duct and plenum items, check material limits, insulation continuity, vapor control, access, listed products, and whether the surrounding space changes the requirement.