Trade walkthroughs
How to inspect insulation before cover
Insulation is a pre-cover inspection by definition: once drywall goes up, you can't see whether a cavity was filled, whether the vapor barrier was continuous, or whether the crew stuffed batts around wiring instead of splitting them. Gaps and compression you can't see later become cold spots, condensation, and energy loss. So the walk happens after insulation and before board.
For the superintendent running the pre-cover inspection and the insulation foreman verifying coverage and barrier continuity before drywall is hung.
Step by step
Confirm the material and R-value against the spec
Verify the insulation type, thickness, and R-value match the energy and architectural specs for each assembly, and that the right product is in the right place — walls, ceilings, rims, and any fire-rated or acoustic assemblies.
Check coverage and fit in the cavities
Walk every cavity for full fill with no gaps, voids, or compression. Batts should be cut to fit, split around wiring and boxes rather than stuffed over them, and fill the full depth — a compressed batt loses much of its value.
Verify continuity at the tricky spots
Check the places crews skip: rim joists, behind electrical panels and boxes, around plumbing, at wall-to-ceiling and wall-to-floor junctions, and in narrow or angled cavities. Continuity is what makes the assembly perform.
Inspect the air barrier and sealing
Confirm air sealing at penetrations, top and bottom plates, and rough openings, and that any air-barrier membrane is continuous and tied to adjacent assemblies. Insulation without an air barrier lets air short-circuit right past it.
Confirm the vapor barrier on the correct side
Verify the vapor retarder is on the correct side of the assembly for the climate, continuous, and lapped and sealed at seams and penetrations. A vapor barrier on the wrong side traps moisture in the wall.
Check spray foam thickness and cure where used
For spray foam, verify thickness against the spec, full adhesion, and that it's cured and trimmed where it interferes with framing or covers. Confirm any ignition or thermal barrier requirement is understood before it's covered.
Verify fire and acoustic assemblies match the listing
Where insulation is part of a rated or acoustic assembly, confirm the material and installation match the tested listing. Substituting or short-filling a rated assembly voids the rating.
Document and release for drywall
Photograph each area's coverage and barrier continuity against the checklist before board goes up, log any gap, compression, or missed area as a nonconformance, and don't release the wall until it's corrected.
What gets missed
- Batts stuffed around wires and boxes instead of split, leaving voids the drywall will hide.
- Compressed insulation that fills the cavity but delivers a fraction of its rated R-value.
- Missed rim joists and areas behind panels — the spots that always get skipped.
- Vapor barrier on the wrong side for the climate, trapping moisture inside the assembly.
- Letting drywall start before the coverage and barrier continuity are photographed and cleared.
Questions people ask
- Why inspect insulation before drywall instead of at final?
- Because drywall covers it permanently. At final you can measure temperature or run a blower door, but you can't see a voided cavity or a compressed batt — the pre-cover walk is the only time the actual coverage is visible.
- What's the most common insulation defect?
- Gaps and compression at the details — batts not split around wiring, missed rim joists, voids behind boxes and in tight cavities. Each one is a thermal bridge and a potential condensation point, and each is invisible once the wall is closed.
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.
Related guides
- How to inspect framingCheck framing before it's covered — members, connections, blocking, and openings against the drawings — so nothing gets buried behind sheathing or drywall.
- How to inspect drywall before closeRun the pre-drywall walk while the walls are open, then inspect board install: backing, fastening, board type, joints and finish level, with proof at each stage.
- How to inspect the building envelopeInspect the envelope as a system — air barrier, water-resistive barrier, flashing, transitions, and sealants — with the continuity and mock-up that make it perform.
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.