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What inspections are required for my Mechanical Permit?*

Washtenaw County Building Department enforces the 2000 Michigan Mechanical Code. Inspections include:


  • Underground, propane gas lines prior to concealing.
  • Rough, all duct work including that under concrete slabs, before concealing.
  • Pre-Fab Fireplace Rough, before any work is covered. (Provide Manufacture's Installation book for inspections.)***
  • Rough, before any work is covered.**
  • Pre-Fab Fireplace Final
  • Final

Air Conditioning

  • Rough, needed if concealed.
  • Final, only if not concealed.

Gas Test

  • A gas pressure test is required on all gas line to code. - 30psi or appropriate gage.
*Trade inspections can be done in conjunction with another inspection on the same permit without an extra fee. For example, more than one inspection can be performed per trip and the cost will be the same as one inspection. The fee is charged per trip.
**Most manufactured homes only need final inspections, because they have been approved at the factory. Exception: Work to the manufactured unit that has been field installed and will be covered must have a rough inspection, including field installed gas lines.
***If you have a mechanical fireplace, the insulation in the chase and its method of attachment must be inspected by the Building Inspector. Do not cover, even if you have an approval from the Mechanical Inspector - that approval is only for the mechanical installation!

What are common violations noted in Mechanical Inspections?

  • Clearance on vents and fireplaces.
  • Firestopping.
  • Gas tests to all gas lines including fireplaces failing due to pressure loss.
  • Venting to manufactures manuals: Hot water heater, furnaces, and prefab fireplaces.
  • Equipment/manufacturer's installation instructions on job site for inspections.
  • Combustion air and make up air.
  • Pressure test on radiant floor heat.
  • Bath fans not installed and vented on rough mechanical inspection.
  • Insulation protection shield on exhaust vents.
  • Wood burning prefab fireplace hearth insulation to manufacturer's specifications with approved safety strips.

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