Asbestos Discovery in an Occupied Apartment Corridor Renovation
You are the lead tilesetter on a corridor and 12 suite-entry renovation in a 1974 six-storey apartment building that remains occupied. The scope is to strip carpet and 300 mm × 300 mm vinyl composition tile (VCT) from the concrete slab, then install 600 mm × 600 mm porcelain. The schedule is five working days with two crews. On day one, while lifting carpet at suite 302, a worker exposes black mastic and cracked VCT; the building's hazardous-materials survey covers only the mechanical room. The general contractor's superintendent says the mastic is 'probably fine' and tells you to keep the crew moving because 40 m of corridor must be open every evening for residents. You have eight workers, one HEPA vacuum, no polyethylene containment, and no negative-air unit. The corridor is the only accessible route to 12 suites, including a resident who uses a walker. Outdoor temperature is 31 °C, so doors are propped open.
1. What must you do immediately when the black mastic and cracked tile are exposed, and why? Address the work area, occupants, and the superintendent.
Read the worked answer
Stop work in suite 302 and isolate the area. In a 1974 building, black mastic and 300 mm VCT are plausible asbestos-containing materials. Do not dry-sweep, chip, or use a standard shop vacuum, and do not treat the single HEPA vacuum as a substitute for containment or sampling. Restrict access, post signage, and keep a clean route past the area so residents can still reach their suites. Notify the owner/GC and the joint health and safety committee in writing; the owner must arrange bulk sampling by a qualified person and laboratory analysis. Tell the superintendent that continuing would spread suspect fibres and create a record of knowingly disturbing a suspect material. Give residents notice and a temporary accessible route; the walker user cannot be routed through a contested work zone. Document the stop-work time, location, photographs, and communications. Your crew does not remove the samples.
2. Assume a bulk sample confirms asbestos in the mastic. Describe the controls and sequence that must be in place before your crew can install tile in that area.
Read the worked answer
The suspect material must be abated by a licensed asbestos contractor, not by the tile crew. Required controls include a sealed containment under negative pressure with HEPA filtration, restricted access, worker training and fit-tested respiratory protection, protective clothing, a decontamination unit, wet methods, and sealed waste removal with manifests. Air monitoring and a clearance test by a qualified person must be completed before containment is removed. After clearance, re-inspect the slab: adhesive residue may remain and may need mechanical removal by grinding or shot blasting to the substrate condition required by the tile adhesive. Only then should layout and tile installation begin. The sequence is: stop work, sample, abate, clear, prepare slab, install tile, and restore egress. No tile work, material staging, or resident access through the contained area until written clearance is issued.
3. The superintendent asks for a written plan to recover the five-day schedule. What do you put in it, and what do you refuse to do?
Read the worked answer
Put in writing that abatement is a separate scope with its own duration and cannot be compressed into the tile schedule. The plan should show suite-by-suite and corridor phasing, a clean temporary walkway that maintains accessible egress, after-hours abatement if the building permits it, separate material staging, and a change order for the delay and abatement coordination. Include hold points: no tile until clearance, no covering of the slab until moisture and flatness are checked, and no reopening of the corridor until adhesives and grout have cured. Refuse to let your crew remove or disturb the suspect VCT, to work inside an uncontained area, or to accept a verbal 'probably fine' instruction. Also refuse to compress mortar cure or grout cure to recover time; that trades schedule for callbacks.