What does this under-slab vapor retarder rough-in checklist cover?

14 items across 4 sections, covering subgrade prepared, surface clear of puncture hazards, perimeter and depth, materials staged for roll-out. Each item spells out what the person walking the job is actually looking for, not just a box to tick.

Who should run this inspection?

The sitework or concrete crew preparing the subgrade, or the GC's superintendent walking the pad before the retarder is rolled out.

When in the schedule should this walk happen?

After the base is placed and compacted, before the vapor retarder is laid down and before any reinforcing is set on top of it.

Why do these items ask for a photo?

10 of the 14 items call for photo evidence, 11 photos in all. A checklist answer without the photo is a claim; the photo is what makes the record worth something in a dispute and lets a reviewer approve work without re-walking the job.

What most often fails an under-slab vapor retarder rough-in inspection?

Sharp rock, rebar chairs or construction debris left on the subgrade that punches through the sheet the moment a crew walks the pad. Base left soft or uneven in spots, so the retarder bridges a void and tears when the slab and crews load it. Grade run high or low against the slab edge, so the retarder ends up trimmed short of where it needs to turn up and tie in.

Can I use this checklist in RTI?

Yes. Start a free RTI workspace, build this list as a checklist, and the Photo Gate holds the submit button until every mandatory item is answered and its photos are attached. Approved inspections roll into a branded turnover package with a tamper evident audit trail.

Free checklist

Under-slab vapor retarder

Under-slab vapor retarder rough-in inspection checklist

Under-slab vapor retarder rough-in is the last time the work is fully visible. Once the cover inspection passes and the walls, ceilings and slabs close, every defect left behind becomes a demolition bill. This checklist walks the rough-in in the order the work goes in, with the photo each item needs before it gets buried. Work is commonly verified against ASTM vapor retarder standards, ACI concrete guidance, manufacturer's published instructions. Confirm the edition your authority having jurisdiction has adopted.

Start free with this checklist Download as PDF

The checklist

Every item, and the photo evidence it needs

The photo count on each row is what RTI would require before the item can be submitted. Work the list here and watch the gate hold, or load it into RTI and let it enforce the real thing.

Subgrade prepared

Base fine-graded, compacted and to grade
Base compacted and graded smooth to the slab elevation, no soft spots or ruts, surface tight enough to support the sheet without bridging.
Sheet position in the slab section confirmed from the details
Drawings read for where the retarder sits, directly under the slab or below a granular layer, and the base graded to suit that section.
No photo
Top of base is the material the drawings call for
Base stone or sand at the surface matches the drawings, with no oversized or angular rock left on top that would press through the sheet under load.

Surface clear of puncture hazards

Sharp debris cleared before the sheet goes down
Rock, rebar offcuts, form stakes and sharp debris removed from the pad so the retarder can lie flat without being punctured.
Under-slab trenches backfilled flush with the base
Plumbing and electrical trenches backfilled, compacted and dressed level with the pad, so the sheet does not sag into a trench line or drape over a spoil ridge.
Stub-ups at final location and braced before roll-out
Pipe and conduit stub-ups set where the layouts show and held rigid, so the sheet can be booted tight and no stub-up gets moved after it is sealed.
Work the drawings put below the sheet finished first
Any soil treatment, radon or vent piping, or under-slab insulation shown below the retarder complete and signed off, so no one lifts the sheet later.
No photo

Perimeter and depth

Grade set so the retarder can turn up at the edge
Subgrade elevation at the perimeter set so the sheet reaches the slab edge or footing and can turn up to tie in, not trimmed short.
Footing and form faces clean where the sheet turns up
Perimeter footing, grade beam or edge form faces free of mud, fins and sharp edges, so the turn-up can be taped or adhered as the detail shows.
Edge termination detail read with the crew
Detail for how the sheet ends at footings, grade beams and thickened edges reviewed with the crew before roll-out, including what it laps or tapes to.
No photo

Materials staged for roll-out

Approved retarder submittal on site with the crew
Approved product data and the manufacturer's installation instructions on hand at the pad, matching the product and class in the specification.
No photo
Roll label shows the specified class and thickness
Label on each roll photographed and compared with the spec and approved submittal: product, class and thickness as specified, not a generic poly sheet.
Seam tape, boots and mastic from the sheet's system
Tape, pipe boots and mastic labels photographed and checked against the products the sheet manufacturer lists for use with this retarder.
Rolls stored and handled as the manufacturer directs
Rolls kept wrapped, off the mud and out of the weather as the instructions say, with no crushed cores or torn outer wraps going onto the pad.

What usually sends this back

The failures are almost always the evidence, not the work

Sharp rock, rebar chairs or construction debris left on the subgrade that punches through the sheet the moment a crew walks the pad.
Base left soft or uneven in spots, so the retarder bridges a void and tears when the slab and crews load it.
Grade run high or low against the slab edge, so the retarder ends up trimmed short of where it needs to turn up and tie in.

Common questions

6 answers

What does this under-slab vapor retarder rough-in checklist cover?: 14 items across 4 sections, covering subgrade prepared, surface clear of puncture hazards, perimeter and depth, materials staged for roll-out. Each item spells out what the person walking the job is actually looking for, not just a box to tick.
Who should run this inspection?: The sitework or concrete crew preparing the subgrade, or the GC's superintendent walking the pad before the retarder is rolled out.
When in the schedule should this walk happen?: After the base is placed and compacted, before the vapor retarder is laid down and before any reinforcing is set on top of it.
Why do these items ask for a photo?: 10 of the 14 items call for photo evidence, 11 photos in all. A checklist answer without the photo is a claim; the photo is what makes the record worth something in a dispute and lets a reviewer approve work without re-walking the job.
What most often fails an under-slab vapor retarder rough-in inspection?: Sharp rock, rebar chairs or construction debris left on the subgrade that punches through the sheet the moment a crew walks the pad. Base left soft or uneven in spots, so the retarder bridges a void and tears when the slab and crews load it. Grade run high or low against the slab edge, so the retarder ends up trimmed short of where it needs to turn up and tie in.
Can I use this checklist in RTI?: Yes. Start a free RTI workspace, build this list as a checklist, and the Photo Gate holds the submit button until every mandatory item is answered and its photos are attached. Approved inspections roll into a branded turnover package with a tamper evident audit trail.

Related checklists

Under-slab vapor retarder Pre-pourUnder-slab vapor retarder pre-pour inspection checklistThe last look before concrete: vapor retarder continuous, laps sealed, penetrations boot-sealed and the sheet tied in at the edge14 items12 photos Under-slab vapor retarder FinalUnder-slab vapor retarder final inspection checklistAfter the pour, the slab edge and penetrations confirmed intact where the retarder tie-in is still visible or documented12 items5 photos

Run it with the Photo Gate

A checklist nobody can submit half-finished

Load this list into RTI, stick a QR tag on the area it covers, and the submit button stays locked until every mandatory item is answered and the 11 required photos exist. Approved walks roll into a branded turnover package with a tamper evident record behind every line.