Nine-Inch Floor Tile and Black Mastic

Why this matters

The 9-by-9 inch floor tile in an old kitchen, bath or basement is one of the most recognizable legacy materials in the country, and one of the most casually ripped out. Whole, it sits there harmlessly under a century of foot traffic. Sanded, ground, scraped, or chipped with a power tool, it and the black adhesive under it can release asbestos fibers into a room that someone is about to live in again. Flooring crews meet it every week, but so do plumbers pulling toilets, HVAC techs cutting register openings, and cleaning crews stripping floors with machines that were never meant for it.

What it is

The tile. Square resilient floor tile, most famously 9 inches on a side, made of asphalt or vinyl with fillers, in common use from roughly the 1920s through the 1970s. Some 12-inch tiles of the same era were made the same way, so the 9-inch size is a strong cue and not the definition. Older tiles are often dark (black, brown, deep red, dark green, marbled), thin, brittle at the edges, and sometimes a little wavy where the floor has moved.

The mastic. Black, tarry adhesive under the tile, often called cutback adhesive because it is asphalt thinned ("cut back") with a solvent. You see it at the edge of a lifted tile, at a doorway threshold, or as a black film on a subfloor where tile was removed. It is a separate material from the tile, made separately, and may contain asbestos when the tile above it does not, or the reverse.

What sits on top of it. These tiles are very often hidden under later flooring: sheet vinyl, carpet, laminate, newer tile. A 1990s floor in a 1950s house can be sitting on the original 9-inch tile and its mastic. The cue is the height of the floor at a threshold, or a glimpse at a floor register or under a toilet base.

Why the hazard is in the method

Intact, bonded, undamaged asbestos floor tile releases very little. The EPA's asbestos rules treat resilient floor covering as a non-friable material while it stays intact, and the federal OSHA construction standard (29 CFR 1926.1101) focuses its flooring rules on how the material is taken up. For employers, that standard sets work practices for removing vinyl and asphalt flooring, including that the flooring and its backing are not sanded, that dry sweeping is prohibited, that tiles are removed intact unless that is shown to be impossible, and that mechanical chipping is done only inside a negative pressure enclosure. It also directs that asphalt and vinyl flooring installed no later than 1980 be treated as asbestos-containing unless the employer demonstrates otherwise. Removing it is Class II work under the standard, supervised by a competent person.

Read that list as a list of what goes wrong on ordinary jobs:

• Sanding a tile floor or its mastic, including a floor sander used to "level" a subfloor before new flooring.
• Grinding mastic off concrete with a grinder or an abrasive wheel.
• Scraping brittle tiles off dry, which shatters them, and dry-scraping mastic.
• Bead blasting or shot blasting a basement slab with tile residue on it.
• Dry sweeping up the pieces afterward.
• Floor care. A high-speed burnisher, or a stripping pad run dry or hard on an old tile floor, wears down the surface. The EPA's guidance for floor care on asbestos-containing resilient floors has long recommended low-abrasion pads, low machine speeds and keeping the floor wet during stripping, and never dry buffing or burnishing down to bare tile.

Who meets it, and what their version of the job looks like

Flooring. The decision is overlay or remove. Overlaying the old floor with new underlayment and flooring leaves it intact, and the main question is whether fastening through it disturbs it in a way that matters; the competent person under the shop's asbestos program evaluates that, or the shop chooses a floating floor or adhesive method that leaves the tile untouched. Removal is regulated work.

Plumbing. Toilet flange replacement, drain cutting through a floor, moving a fixture. The cut is small but it is a cut.

HVAC. Cutting a new floor register opening, or enlarging an old one, through tile and mastic.

Electrical. Floor boxes, or fishing through a floor.

Appliance. Removing an old dishwasher or range and finding the floor under it has not been touched in decades; pulling up a loose tile to level the new unit.

Cleaning. Stripping and refinishing old commercial-looking tile floors in homes, rental turnovers and small offices.

Presume and avoid until tested

The working rule for every one of those trades: presume the tile and the mastic are both asbestos-containing until a lab says otherwise, and choose the method that leaves them intact. That means:

• Choose the repair that does not cut the floor, where one exists.
• Choose the floor-care method that does not abrade it.
• Choose overlay over removal where the owner's goal allows it.
• Where the job cannot avoid cutting, scraping or removing, the material is tested first by a licensed inspector, or the work goes to a contractor who works under the standard.

Two samples, not one. Because the tile and the mastic are separate products, the inspector samples them separately. A result on the tile says nothing about the mastic. That is the single most common misreading of a floor test.

The worked example: a toilet flange on a 1958 bathroom floor

The call. A rocking toilet in a 1958 house, with a damp subfloor smell. The bathroom has its original 9-by-9 tile, dark green, with black mastic visible at the doorway edge.

What the plumber sees when the toilet comes off. The plumber shuts the water at the toilet supply valve, flushes and sponges the bowl and tank dry, disconnects the supply, and lifts the toilet straight off the bolts onto a drop cloth in the tub, without rocking it across the tile. Under it: a cast iron closet flange with one bolt slot broken and the wax ring failed. The tile around the flange is intact, with a ring of old wax and grime. The usual repair on this flange would cut out a ring of tile around it to set a new flange at the right height, and that is the cut that stops the plan.

The two paths, in hours.

• Path A: avoid the floor. Install a repair ring that bolts to the existing cast iron flange through its own holes, not screwed down into the floor, or an internal flange that seals inside the pipe, with a thicker wax ring or a foam seal to make up the height. No tile cut and no fastener through the tile. About 1.5 hours.
• Path B: test first, then cut if clear. A licensed inspector samples the tile and the mastic separately; the plumber resets the toilet temporarily on a new wax ring so the house has a working toilet, and returns after results. If both are clear, the tile ring is cut and a new flange set to height, about 2.5 hours across two visits. If either is positive, the ring of tile is removed by a contractor under the standard before the plumber returns.

What the test produced. The owner wanted the full repair, so they chose Path B. The illustrative results came back with the tile "none detected" and the mastic "positive, chrysotile." The plumber's planned cut goes through both. The mastic result, not the tile result, decided the plan. The plumber explains to the owner that the tile result looks like good news on its own, but the cut goes through both materials, and the one that tested positive is underneath. The cut is not plumbing work now.

The revised plan. The owner chooses Path A after all, rather than paying for a contractor to remove a small ring of floor. The plumber bolts the repair ring to the old flange without fastening into the tile, sets it with a foam seal suited to the extra height, and sets and secures the toilet.

Putting water back. With the toilet set, the plumber opens the supply valve slowly with a hand on the supply line, watches the connection at the valve and the tank for drips while the tank fills, flushes several times, and checks the base and the floor around it with a dry paper towel for any water. The base caulk is applied only after a dry check. If the seal weeps, the toilet comes back off, water off first, and the seal is redone; the tile is still not cut.

Counting the visits. Path B as chosen: one visit to pull the toilet and assess, one inspector visit, one visit to finish. Three visits, of which two were the plumber's. Path A from the start would have been one visit. The extra visits bought the owner a known answer about the floor, which is now on the record for the next trade, and that record is the reason Path B is still worth offering.

What changes the answer. If the subfloor under the flange were rotted, the floor has to be opened regardless and testing or contractor removal is unavoidable; Path A is off the table. If the tile had been under a newer floor that the owner wanted removed anyway, the whole floor becomes a flooring removal question for a contractor under the standard. If both samples had come back clear, Path B's cut proceeds as ordinary work, and the record says so.

The cleaning crew's version

A rental turnover with an old 9-inch tile floor the property manager wants "stripped and waxed." The crew uses the low-abrasion approach: a wet strip with a mild stripper, a low-speed machine with a non-aggressive pad, no dry buffing, no high-speed burnishing on a floor worn down to bare tile, and a wet pickup rather than sweeping. Broken or loose tiles are not pried out and are noted for the manager. Where the floor is badly worn, cracked or already broken up, the crew declines the strip and says why, because the method no longer leaves the floor intact.

How to verify you got this right

You chose the method by what it does to the floor, and the record states it: "no cut, repair ring bolted to the old flange, nothing fastened through the tile" is a method; "careful" is not.

Tile and mastic have separate entries, separate results, and separate consequences on the plan.

Pieces stayed whole. Nothing was swept dry, ground or sanded, and any loose tile you moved was moved whole.

References

• 29 CFR 1926.1101, OSHA construction asbestos standard, including its work practices for removing vinyl and asphalt flooring.
• U.S. EPA guidance on floor care for asbestos-containing resilient flooring.
• Your state asbestos program for inspection and licensing rules in homes.
• See related: Asbestos-Suspect Materials by Location in a House; How to Get a Suspect Material Tested Without Becoming the Sampler.
• See related: Job Site Asbestos Discovery Stop Work Protocol.