Dust Control on an Interior Repair

Purpose

A handyman patch makes a small volume of dust and a large distribution problem. What comes off a 2 sq ft ceiling repair would fit in a coffee can. Uncontrolled it lands in four rooms, on a piano lid, and inside a return grille that then blows the fine fraction through the house for a week.

This procedure guarantees that before an abrasive or cutting tool runs indoors, the material is named along with every route it can reach a person by, the dust is captured at the tool rather than chased around the room, the air moves in one proven direction, and every service, seal and alarm the containment disabled is restored and tested before the tech leaves. The failure it prevents is the visit that produces a good patch and a customer who finds gray film two floors away on Thursday.

Scope

Covers interior repair in an occupied house, apartment, small office or small retail space where sanding, cutting or demolition liberates airborne material: drywall and plaster patching, tile and mortar cutting, small masonry work, trim removal.

Explicitly not covered:

• Floor and path protection and moving customer property, owned by the job site setup procedure. Floor protection is not containment.
• Final cleaning and the walkthrough, owned by the end-of-visit cleanup procedure. This one ends when the containment is down and the space outside it proves clean.
• Coated surfaces in pre-1978 target housing, regulated under 40 CFR Part 745 Subpart E, which routes to the pre-1978 paint disturbance procedure BEFORE anything here is built.
• Suspected asbestos in textured ceilings, old floor tile or pipe wrap, and visible mold beyond a small area. Both are a stop and a referral.

Roles and responsibilities

The procedure

1. Name the material and every route it can reach a person by, before a tool comes off the truck. Acceptance: a written line naming the substrate (joint compound, plaster, mortar, tile body, mineral wool, hardwood) and each route this job's imperatives open: inhalation from cutting, ingestion from hands and food, contact to skin and eyes. Wrong looks like "drywall dust" written on a 1961 house whose walls are plaster over wood lath. Stop rule: pre-1978 with coated surfaces in the disturbance, or any suspicion of asbestos or mold, stops here and hands off. Hazard: none at this step, it is a decision made at the truck, and it sits first so the calls downstream get made once.

2. Shut the forced-air system down and seal every supply and return inside the boundary, counting what you closed. Acceptance: system off at the thermostat and at its service switch where one exists, every register and grille inside the work area taped on all four edges, count written, for example "3 supplies, 1 return." Wrong looks like sealing supplies and leaving the return open, which is the opening that pulls dust into the air handler and redistributes it. Stop rule: a return you cannot seal without covering a combustion air opening means the boundary moves to exclude it. Hazard: never seal an appliance vent, draft hood or combustion air opening, because that is a carbon monoxide event, not a dust one.

3. Build the boundary before anything is disturbed, and give it a real door. Acceptance: 6 mil sheeting floor to ceiling across every opening, sealed on all four edges, with a zipper door you can pass one-handed, and no billow when that door is worked. Wrong looks like a sheet stapled at the head only, which vents at the bottom on the first cord pull. Stop rule: a surface the tape will not hold or will damage, such as a textured ceiling, gets a spring pole system instead. Hazard: sheeting across a walking route is a trip, so weight every ground edge, and the boundary never closes off the room's only means of egress.

4. Capture at the tool first, and treat room air as the second line. Acceptance: every sander, grinder or saw on a shroud connected to a HEPA vacuum, meaning a filter rated 99.97 percent at 0.3 micrometer, running before the tool touches the surface. Wrong looks like dry sanding with an air machine in the corner, because a room machine dilutes a concentration and captures nothing at the source. Stop rule: no shroud or no working HEPA vacuum means the task goes hand and wet, or it reschedules. Hazard: compound, plaster, mortar and masonry release respirable crystalline silica when cut, ground or sanded, controlled at 29 CFR 1910.1053 in general industry and 1926.1153 in construction, whose Table 1 pairs task, control and respirator requirement; and a respirator counts only inside a written program per 29 CFR 1910.134, so no program means no task that needs one. Sanding or cutting the trim in the same scope liberates wood dust instead, which is a respiratory irritant and, for hardwoods, a recognized carcinogen, so the shroud and HEPA control applies to that tool too.

5. Set the air moving one direction, exhaust outdoors, and prove the direction before you cut. Size it from the room: volume in cubic feet, times design air changes per hour, divided by 60, is the cfm the machine must still deliver on a loaded filter. Four air changes per hour is the convention IICRC S520 sets for mold remediation, in the edition that trade works to; it binds a remediator, not you, and is used here as a starting point. Acceptance: computed cfm written down, machine rated above it with margin, exhaust ducted through a window block to outdoors, a named makeup path, and smoke at the door gap drawn in rather than out. Stop rule: no outdoor path means the machine runs in recirculation as a scrubber only and the ticket says so. Hazard: pulling a room negative in a house with an atmospherically vented water heater or furnace can reverse that appliance's draft and bring flue gas inside, so put a CO monitor beside the appliance, fire it, and check draft at the hood with smoke after about a minute; if smoke rolls out instead of in, or the monitor moves off zero, shut the machine down, open a makeup path near the appliance, and re-test.

6. Control the crossings and the ingestion route, not just the boundary. Acceptance: everything for the task staged inside before the door closes, so a crossing is an event you can name rather than a habit; a tack mat inside the door; occupant and pets outside with the alternate route named to them aloud. Stop rule: anyone entering unannounced stops the tool until they are back out. Hazard: dust on hands is an ingestion route independent of what you breathe, so nobody eats or drinks inside the boundary and hands and face get washed before touching the truck; the same dust is a contact hazard, so eye protection stays on overhead.

7. Take the containment down wet and in order, then prove the space outside it is clean. Acceptance: sheeting HEPA vacuumed on its inner face before anything moves, misted, folded inward on itself, bagged and out of the house; then a white-cloth wipe on a horizontal surface outside the boundary at three named spots, each coming back clean. Wrong looks like pulling poly dry, which releases in ten seconds what the boundary spent four hours collecting. Stop rule: a gray wipe means that area is cleaned to the same standard and re-wiped before the walkthrough. Hazard: changing a loaded bag is the highest short exposure of the day, so do it outdoors and never blow a filter out with compressed air.

8. Restore every service, seal and alarm the containment disabled, and prove each protective function still works. Acceptance: seals removed and counted against step 2's number with the two counts matching; system back on and run one full cycle; every alarm cover removed and each smoke and CO alarm sounded on its own test button; exhaust window closed and latched; the appliance from step 5 re-fired with the machine off and its draft re-checked. Wrong looks like an alarm left bagged behind a door, which is how a dust job becomes a fire fatality with the shop's tape on it. Stop rule: an alarm that will not sound, or an appliance whose draft does not re-establish, goes to the occupant and the lead before the tech leaves. Hazard: this step puts air movement, fuel and combustion back into a building you have been manipulating, so tell the occupant before you fire anything and stand clear of the appliance face on light-off.

The record this produces

A containment block on the ticket, reached the first time a customer reports dust in a room nobody worked in:

• Material and routes: substrate, year built with its source, routes listed, and the pre-1978 or asbestos question answered yes or no.
• HVAC: openings sealed by type and count, and the matching count at restoration.
• Boundary and capture: what was sheeted, how the door was made, which tools ran on shroud and vacuum.
• Airflow: room volume, air changes per hour, computed cfm, machine rating, exhaust destination, makeup path, and the draft and CO result at the vented appliance.
• Takedown and restoration: three wipe locations with results, seals removed, each alarm tested by name and location, appliance draft re-checked.

The lead reads the airflow and restoration lines on any callback.

Worked pass: bedroom ceiling patch after a roof leak, 1996 two-story

Booked at 4.0 hours: cut out and replace a water-stained ceiling section about 2 ft by 3 ft, tape, coat and sand.

Step 1: gypsum board and joint compound; 1996 confirmed from the county assessor record, so the pre-1978 route does not fire. Routes written: inhalation of respirable silica from sanding compound, ingestion from hands, contact to eyes overhead.

Steps 2 through 4: three supplies and one return inside the room, all four sealed on four edges, thermostat off and tagged. Doorway and closet opening sheeted in 6 mil with a zipper door, tape holding at the head on smooth painted board. Random-orbit sander on a shroud into a HEPA vacuum with a fresh bag.

Step 5 FAILED and took its stop rule. The room measures 12 ft by 14 ft with an 8 ft ceiling, so 12 times 14 is 168 sq ft and 168 times 8 is 1,344 cu ft. At 4 air changes per hour, 1,344 times 4 is 5,376 cu ft per hour, and 5,376 divided by 60 is 89.6 cfm required. The truck machine is rated 500 cfm, so 500 divided by 89.6 is about 5.6 times the computed requirement, and that margin is why it still holds a boundary on a loaded filter. Exhaust went out the bedroom window on a block, with makeup drawn from the hall, which passes an open utility closet holding a natural-draft gas water heater. On the pre-run check the heater was fired and at about one minute the smoke at the draft hood rolled OUT rather than in, with the CO monitor on the closet shelf still reading 0 ppm. Acceptance requires smoke drawn in, so the machine was shut down. Fix: a utility-area window opened about 6 in as a makeup path, heater re-fired, and on re-test the smoke was drawn into the hood and held a full 60 seconds with the monitor at 0 ppm. Only then did the cut start.

Steps 6 through 8: the tech crossed the boundary twice in 3.5 hours. Three wipes outside it, on the hall floor about 3 ft from the door, on the stair newel cap and on the bathroom counter across the hall, all three clean. Four seals off against four sealed at step 2; system cycled once; both smoke alarms on that floor sounded on their own test buttons; window closed and latched; machine off and the water heater draft re-checked with the utility window closed, smoke drawn in and held. Step 5's stop rule fired on the appliance rather than on the dust, which is why the draft check sits ahead of the cut.

References

• 29 CFR 1910.1053 and 29 CFR 1926.1153, respirable crystalline silica in general industry and in construction; Table 1 of the construction standard pairs task, control and respirator requirement.
• 29 CFR 1910.134, respiratory protection, which makes a written program with medical evaluation and fit testing the condition on any respirator use.
• 40 CFR Part 745 Subpart E, which governs before this procedure applies in pre-1978 target housing.
• See related: Job Site Setup and Floor Protection; End-of-Visit Cleanup and Walkthrough; Pre-1978 Paint Disturbance: Stop and Assess; Drywall Patch and Finish Standard.
• Manufacturer manuals for the vacuum and air machine state the filter change indication and the rated airflow at loading.