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Trade walkthroughs

How to inspect HVAC rough-in

HVAC rough-in decides how the building will breathe for its whole life, and most of what governs that — the duct sealing, the support, the pitch on a condensate line — vanishes behind the ceiling grid. This walkthrough follows the air and refrigerant paths in the order they are built, so the leaks and sags get caught while a ladder still reaches them.

For the mechanical foreman checking their own rough-in, or the GC's superintendent confirming it before ceilings, chases and walls are closed.

Step by step

  1. Verify duct construction and layout against the drawings

    Duct should be the gauge, seam and reinforcement class the design calls for, routed on the coordinated path with the clearances it needs. Check that sizes were not quietly reduced to fit a tight ceiling.

  2. Check sealing and joints

    Transverse and longitudinal joints should be sealed to the required class, with mastic or listed tape, not left to leak into the plenum. On sealed systems, confirm the duct leakage test was run and recorded before the ceiling closes.

  3. Inspect hangers and support

    Duct and equipment should hang from supports at the required spacing, sized for the load, with no crushed flex and no run sagging between hangers. Trapeze and rod supports should be anchored to structure, not to another trade's work.

  4. Confirm equipment set and serviceable

    Air handlers, VAV boxes, fan coils and RTUs should be set level, isolated where required, and left with the clearance a technician needs to service and pull filters. Verify each unit is the tagged model for its location.

  5. Check refrigerant piping and its test

    Refrigerant lines should be supported, insulated, and under the pressure or leak test the design requires before being buried. Observe and record the test holding — the mechanical contractor runs it, you document it.

  6. Verify condensate routing and pitch

    Condensate drains should be trapped correctly for draw-through or blow-through, pitched to drain, and routed to an approved point — not left to a ceiling tile. A flat or reverse-pitched condensate line floods a room the first hot week.

  7. Log penetrations and photograph before cover

    Every duct or pipe through a rated wall or floor gets flagged for firestopping and the required damper. Photograph the sealed duct, the supports and the tested refrigerant lines, tied to the zone, before the ceiling goes in.

What gets missed

  • Duct seams left unsealed above a hard ceiling that can never be reached to fix.
  • Flex duct crushed over a support or kinked around a beam, choking the airflow the balance report will later blame on the fan.
  • Condensate lines run flat or without a trap, so they back up the first time the coil sweats.
  • Smoke and fire dampers missing at rated penetrations, caught only at the fire-alarm and life-safety walk.
  • Refrigerant lines buried before the leak test was witnessed and recorded.

Questions people ask

Should I run a duct leakage test at rough-in?
Where the design or energy code requires one, yes — and it has to be run and recorded before the ceiling closes over the duct, because a failed test after cover means opening the ceiling to find the leak.
What is the difference between this and the final HVAC inspection?
Rough-in verifies the buried construction — duct, support, piping, penetrations — while it is still exposed; the final confirms the finished, running system with its dampers, diffusers and controls in place.

Standards behind it

Terms worth knowing

Checklists that make this a one-tap job

Free, field-ready checklists, each with the photo every item needs before it can be submitted.

HVAC Rough-in· HVACHVAC rough-in inspection checklistDuctwork, refrigerant lines, condensate and equipment setting before the walls and ceilings close8 items13 photosHVACHVAC inspection checklistEquipment set, duct, condensate, controls and startup readings.14 items24 photosHVAC Pre-cover· HVACHVAC pre-cover inspection checklistThe above-ceiling walk before the grid and drywall close on ductwork and lines7 items11 photosHVAC Final· HVACHVAC final inspection checklistGrilles, registers, balancing and controls verified before startup and turnover7 items9 photos
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Related guides

Reading the steps is one thing. Proving you walked them is the job.

RTI holds the submit button until every mandatory item is answered and the photos are attached, then chains the record so it can be proven untouched later.

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