The Black Mastic Under the Old Carpet

Why this matters

Old carpet hides what was on the floor before it. In a house with flooring installed in 1980 or earlier, that is often 9-inch resilient tile set in black adhesive, and both are presumed to contain asbestos until a lab says otherwise. The crew that keeps pulling once it sees them turns a floor replacement into an exposure event, for themselves and for the family living there. This case covers the hour after the discovery, the week waiting on results, and how the job was rebuilt around what the lab found.

The stop

The shop was replacing carpet with glue-down luxury vinyl plank in the basement family room of a 1964 ranch, about 18 by 24 feet. On the morning of tear-out, the crew had cut the carpet into strips and rolled back the first two. Underneath the old pad sat dark 9 by 9 inch tiles, a few cracked, and along one wall a patch where tiles were missing and black adhesive showed on the concrete.

The crew lead stopped the tear-out there. What had already happened mattered: rolling carpet and pad off the tile had not broken or abraded it. What came next would have. The plan for the day was to pull the tackless strip, which is nailed through the tile into the slab, and then scrape the floor smooth for glue-down. Both disturb tile and adhesive.

So the stop was specific, and the crew lead said it out loud to the crew before he said anything to the homeowner:

• Nothing more comes up. The rolled carpet stays rolled, the strip stays nailed, no scraping, no prying at loose tiles.
• No dry sweeping and no shop vacuum. Broken pieces and dust on the floor stay where they are. A shop vacuum without a HEPA filter blows fine fibers through its exhaust.
• The forced-air return in the room gets closed off. The basement return grille was taped over with poly so the furnace blower could not pull dust from the room into the rest of the house.
• The room gets closed. The door at the top of the stairs was shut and the homeowner was asked to keep children and the dog out.

Why stop at the first sight of the tile rather than after a quick look under more carpet? Because the presumption does not need more evidence. Any resilient floor or black adhesive of unknown age is treated as asbestos-containing until tested, and for an employer the federal rule is explicit: OSHA's construction asbestos standard, 29 CFR 1926.1101, requires asphalt and vinyl flooring installed no later than 1980 to be treated as asbestos-containing unless the employer proves otherwise by testing. Removing that flooring, or its adhesive, is Class II asbestos work under that standard, which calls for trained workers, specific work practices and exposure monitoring. This crew was not trained for Class II work, and the shop's policy is that it does not do it.

The conversation

CREW LEAD: We have to stop for today. Under the carpet
  is old 9 inch tile and black glue. On a house this
  age we treat both as asbestos until a lab says no.
HOMEOWNER: It's been under carpet for thirty years.
  Is the house contaminated?
CREW LEAD: Intact tile under carpet is not releasing
  much. It's breaking and scraping it that does.
  We stopped before we did either.
HOMEOWNER: So what happens to Monday's install?
CREW LEAD: It moves. A sample goes to a lab first.
  We get results in a few business days. If it's
  clean, we pick up where we left off. If not,
  we have two ways forward and we'll lay them out.
HOMEOWNER: Can't you just glue the new floor down
  over the old tile?
CREW LEAD: Not this floor. Glue-down needs the floor
  scraped and leveled, and that is the disturbance.
  If the test comes back positive, the options are
  having a licensed abatement crew remove it, or
  leaving it in place under a floor that does not
  need it disturbed.

The crew lead also told her what the room needed until results came back: door closed, nothing walked across the bare patch, nobody vacuuming down there. He did not tell her the tile was dangerous or safe, because he did not know yet, and an untested answer in either direction is the one thing he could not take back.

Testing

Who takes the sample. Some states and localities require samples to be collected by a licensed or accredited asbestos inspector; others let the property owner or a contractor collect them. The shop's office checked the local rule that morning. Here a state-accredited inspector was required, and the office scheduled one for the next day.

What gets sampled. The tile and the adhesive are separate materials and are tested separately. A tile can test negative over an adhesive that tests positive, and the reverse. The inspector took one tile sample and one adhesive sample from the patch where tiles were already missing, wetting each before cutting so no dust was raised, and patched the sample spots.

The lab. Samples went to a lab accredited for bulk asbestos analysis by polarized light microscopy, the standard method for floor tile and mastic. Standard turnaround was quoted at several business days, with faster turnaround available at extra charge; the homeowner chose standard.

The schedule change, in writing. The office sent the homeowner a written note the same afternoon: tear-out paused, the inspection date, the expected result date, and that the install date would be reset once results were in. The crew was moved to another job for the week. The rolled carpet stayed in the room, untouched.

The results and the fork

Results came back four business days later: the tile tested positive for chrysotile asbestos, and so did the black adhesive.

Had both come back negative, the crew would have resumed the original glue-down plan with one limit on what the result clears. A negative covers the material sampled and nothing else. A second layer of older tile under the first, a different color or size of tile in a closet, a patch of a different adhesive, or a sheet vinyl remnant under a doorway is a separate material with its own presumption, and the crew would have stopped again on finding any of them. Inspectors call each distinct material a homogeneous area for that reason. The scrape-and-prep would also still have been run as silica-generating work on the concrete, under the shop's 29 CFR 1926.1153 plan.

The positive results converted the presumption into a fact and left two paths. Both are built on the same rule: the material is safest left intact and undisturbed, and any removal is done by people licensed and trained to do it.

Path A, abate and glue down as planned. A licensed asbestos abatement contractor removes all the tile and the adhesive under the containment, work practices and disposal the state and local rules set, then the shop preps and installs the glue-down plank. Removing the black adhesive from concrete is its own step, and how it is done is the abatement contractor's call within those rules. This path leaves no asbestos in the house. It also adds the most time.

Path B, limited abatement and encapsulation. Leave the intact tile and adhesive in place and cover them with a floor that does not require disturbing them. A glue-down plank is out, because it needs a scraped, leveled surface. A floating floor over an underlayment can go directly over sound, well-bonded resilient tile where the flooring maker's instructions allow installation over existing resilient flooring. Two things still had to come out: the perimeter tackless strip, nailed through the tile, and the broken and loose tiles along the wall. Those were scoped to the abatement contractor as limited removal, with the bare patch then filled with a patching compound applied over the remaining adhesive rather than scraping it, where the flooring and patch makers permit it.

Encapsulation is one allowed path, not a universal one. It depends on the flooring maker's instructions allowing installation over existing resilient tile, on the tile being sound and well bonded, and on the state and local rules where the house sits. Federal EPA asbestos NESHAP rules at 40 CFR Part 61, Subpart M generally do not reach a single-family home, but some states and localities regulate residential asbestos work directly, including who may remove it and how it is disposed of, so the office confirmed the local rule before offering this path.

The homeowner chose path B. The new floor went from glue-down plank to a rigid-core floating plank, which also meant re-pricing and re-dating the job in a written change order she signed before any work restarted.

How the job finished

The abatement contractor removed the perimeter strip and the damaged tiles in one day under its own containment and provided its clearance documentation. With that in hand the basement return grille was uncovered and the furnace run to confirm it pulled air from the room again. The shop came back the following week. The crew checked the remaining tile for bond by tapping and pressing every tile in the field: none loose. The patch was flat to the floor maker's tolerance, the underlayment went down, and the floating floor went in with its expansion space at the walls, hidden by base and never pinned. Nothing in the shop's scope touched the tile below.

The record the homeowner keeps

The crew lead gave the homeowner copies of the lab report, the abatement contractor's documents, and a short note stating that asbestos-containing tile and adhesive remain in place under the family room floor, with the date and the floor installed over them. Whoever works on that floor next needs to know before they cut into it. Whether that has to be disclosed at a sale depends on her state's law, which is a question for her agent or attorney.

References

• 29 CFR 1926.1101, Asbestos (construction), including the presumption for flooring installed no later than 1980 and Class II work.
• 40 CFR Part 61, Subpart M, National Emission Standard for Asbestos, and your state and local asbestos rules.
• Flooring manufacturer's instructions on installation over existing resilient flooring.
• See related: Nine-Inch Floor Tile and Black Mastic; Asbestos in Old Resilient Floors and Adhesive; The Old Floor Removal and Disposal SOP.