6.3 High-Risk Components, Common Areas, and Dust Pathways
Key Takeaways
- A component (745.223) is a building element distinguished by form, function, and location — interior lists run from ceilings and doors through window sashes, sills or stools, and troughs; exterior lists run from siding and soffits through sashes and wells.
- A common area is a portion of a building generally accessible to all occupants: hallways, stairways, laundry and recreational rooms, playgrounds, community centers, garages, and boundary fences (745.223). In multi-family housing, common-area paint and dust can re-contaminate cleared units.
- A living area is any area of a residential dwelling used by one or more children under age 6, including living rooms, kitchens, dens, play rooms, and children's bedrooms (745.223). Risk-assessment dust wipes target floors and interior window sills in those areas.
- Dust-lead hazards on or after January 12, 2026 are any reportable level on floors and interior window sills. Window troughs are not in that hazard definition, but they are a post-abatement action-level surface at 100 µg/ft² (action levels 5 / 40 / 100 on floors / sills / troughs). Do not teach 40 / 250 / 400 as current.
Name the component, then name the pathway
Quick Answer: 745.223 defines a component by form, function, and location, a common area as space generally accessible to all occupants, and a living area as any part of a dwelling used by one or more children under age 6. Dust-lead hazards on or after January 12, 2026 are any reportable level on floors and interior window sills. Window troughs are not in that hazard definition, but post-abatement action levels are 5 µg/ft² floors, 40 µg/ft² interior window sills, and 100 µg/ft² window troughs. Chips on the dripline after exterior work must be removed (745.227(e)(8)(v)(C)).
A supervisor who says "the bedroom is dusty" has not recognized a hazard. A supervisor who says "the lower sash is a friction component, the stool is the interior sill, the well is the trough, and the hallway common-area floor can re-contaminate Unit 2" is ready to write an occupant protection plan.
The 745.223 component list is the inventory
Component or building component means specific design or structural elements or fixtures of a building, residential dwelling, or child-occupied facility that are distinguished from each other by form, function, and location. The regulation then lists examples. Those examples are the high-risk inventory you walk.
| Interior components (745.223 examples) | Why they show up on jobs |
|---|---|
| Ceilings, crown molding, walls, chair rails | Large planes for deteriorated LBP; chair rails also sit in the chewable zone |
| Doors, door trim | Friction at the jamb; impact at the stop and the wall opposite the knob |
| Floors | Friction under traffic; the child's dust-contact surface; wipe-sample hazard surface |
| Fireplaces, radiators and other heating units | Distinct painting history; dust on horizontal tops |
| Shelves, shelf supports, built-in cabinets, vanities, counter tops | Horizontal dust shelves; chewable edges at child height |
| Stair treads, risers, stringers, newel posts, railing caps, balustrades | Friction on treads; chewable rails and newels; common-area stairs in multi-family |
| Windows and trim, including sashes, window heads, jambs, sills or stools and troughs | Friction pair plus the two dust shelves (sill and trough) |
| Columns, beams, air conditioners | Distinct components; AC sleeves punch through to exterior dust |
| Exterior components (745.223 examples) | Why they show up on jobs |
|---|---|
| Painted roofing, chimneys, flashing, gutters and downspouts | Water paths that fail paint and dump chips at the dripline |
| Ceilings, soffits, fascias, rake boards, cornerboards, bulkheads | Small-component 10% test (soffits, trim) vs large siding planes |
| Siding, floors, joists, lattice work | Large exterior poor-condition test at 10 ft² |
| Doors and door trim, fences, railings and railing caps, handrails, balustrades, columns | Impact, chewable rails, boundary fences as common areas |
| Stair risers, treads, stringers | Exterior friction and deteriorated paint over play areas |
| Window sills or stools and troughs, casings, sashes and wells, air conditioners | Same window anatomy as interior, now weathering into soil |
A window is not one component. Sash, jamb, head, sill/stool, trough/well, and casing each have form, function, and location. Inspection reports test distinct painting histories. Your work order should too. Replacing "the window" is a method. Wet-scraping "the window" without saying which piece is how crews miss the trough.
Window trough (745.63): on a typical double-hung, the portion of the exterior window sill between the interior window sill (or stool) and the frame of the storm window. If there is no storm window, the trough is the area that receives both the upper and lower sashes when they are both lowered. Field language still says window well. Same place.
Common areas re-contaminate units
Common area means a portion of a building that is generally accessible to all occupants. Such an area may include, but is not limited to, hallways, stairways, laundry and recreational rooms, playgrounds, community centers, garages, and boundary fences (745.223).
Multi-family dwelling means a structure that contains more than one separate residential dwelling unit. In that building the hallway is not a courtesy walk-through. Risk assessment in multi-family and COFs requires interior window-sill and floor dust samples in common areas adjacent to the sampled unit and in other common areas where children under 6 are likely to contact dust (745.227(d)(6)). Inspections must test each component with a distinct painting history in every common area (745.227(b)(2)(ii)).
Why the supervisor cares: you can abate Unit 4 to a clean visual, then watch occupants track hallway dust back onto the Unit 4 floor. Playground paint on a boundary fence, a laundry room window trough, and a stair railing are common-area hazards that keep feeding units. Treat common-area abatement as an occupant-protection and containment problem (Chapters 8, 10, and 11). Do not schedule Unit 4 clearance while the stairwell beside it is still being scraped. Common area group (745.63) is the assessor's clustering tool — similar hallways, stairwells, laundry rooms — so one failed sampled hallway can speak for unsampled hallways in the same group (745.227(h)(3)(iii)). You still contain the hallway you are working.
Living areas are where children use the dwelling
Living area means any area of a residential dwelling used by one or more children under age 6 including, but not limited to, living rooms, kitchen areas, dens, play rooms, and children's bedrooms (745.223). It is a use definition, not a floor-plan label. A dining room where a toddler eats and plays is a living area. A locked, unused attic is not, unless children actually use it.
Risk-assessment dust sampling in a residential dwelling collects floor and interior window sill samples in all living areas where children under 6 are most likely to come into contact with dust (745.227(d)(5)). That is why floors and sills — not troughs — define the dust-lead hazard. Children crawl and sit on floors. Children lean on stools. They do not typically play down in the trough; the trough still feeds the sill and the floor.
How dust actually moves
Lead dust does not stay on the component that generated it. High-risk pathways on a real job:
| Pathway | Mechanism | Where it lands |
|---|---|---|
| Window friction | Sash grinds jamb and well; paint becomes dust | Trough first, then interior sill, then floor under the window |
| HVAC returns | Returns pull room air — and dust — into ducts and blow it to other rooms | Floors and sills far from the work; furniture tops |
| Tracked dust on shoes | Crews, occupants, and visitors walk through dust or soil | Floor wipe locations along paths of travel, including outside containment |
| Exterior soil tracked in | Bare soil at the dripline and play area (soil-lead is Chapter 15) | Entry floors; living-area carpets |
| Friction grinding on floors and stairs | Painted treads and floors under feet | The floor itself — child's primary contact surface |
| Deteriorated exterior paint | Chips and dust fall | Dripline soil and horizontal outdoor living surfaces |
Children's wipe-sample story: the hazard definition follows the child. Floors and interior window sills are the two surfaces in 745.65(b) and 745.227(h)(3). On or after January 12, 2026, a dust-lead hazard is any reportable level of lead on those two surfaces (NLLAP laboratory, no "less than" qualifier — reportable level, 745.63). Abatement is still complete only when dust is below action levels. Those two ideas stay separate through Chapter 18.
Why troughs appear on clearance anyway
Post-abatement sampling is not a reprint of the hazard definition. 745.227(e)(8)(v)(A)–(B) requires dust samples from an interior window sill and from one window trough (if present) and from floors, inside containment (and one floor outside containment when containment was used). 745.227(e)(8)(viii) sets action levels on or after January 12, 2026 at 5 µg/ft² for floors, 40 µg/ft² for interior window sills, and 100 µg/ft² for window troughs.
| Surface | Dust-lead hazard (on/after 2026-01-12) | Post-abatement action level (on/after 2026-01-12) |
|---|---|---|
| Floors | Any reportable level | 5 µg/ft² |
| Interior window sills | Any reportable level | 40 µg/ft² |
| Window troughs | Not a 745.65(b) hazard surface | 100 µg/ft² |
That is why a trough can "fail clearance" at 100 µg/ft² even though a dust-lead hazard is not defined on troughs. The trough is a reservoir. If you leave it dirty, the next rain and the next sash movement put that dust on the sill — and the sill is a hazard surface at any reportable level. Supervisors who "skip the wells because hazards are only floors and sills" fail the visual or the trough wipe and then reclean.
Do not teach 40 / 250 / 400 µg/ft² as current. Those are obsolete HUD/EPA figures. The pre-January 12, 2026 action levels were 10 / 100 / 400. Current action levels are 5 / 40 / 100. Current dust-lead hazards on floors and sills are any reportable level, not 40 or 10.
Exterior chips, dripline, and the daily walk
Dripline (745.63) is the area within 3 feet surrounding the perimeter of a building. After exterior paint abatement, 745.227(e)(8)(v)(C) requires a visible inspection: all horizontal surfaces in the outdoor living area closest to the abated surface shall be cleaned of visible dust and debris, and a visual shall look for paint chips on the dripline or next to the foundation below any exterior surface abated. If paint chips are present, they must be removed from the site and properly disposed of. That is a supervisor walkthrough item every afternoon of an exterior job, not a surprise at clearance day.
Connect the chapter:
- Components tell you what can fail (sash, sill, trough, door, baseboard, siding, fence).
- Friction, impact, chewable, and other deteriorated LBP (Sections 6.1–6.2) tell you which failures are paint-lead hazards.
- Pathways tell you where the dust will be tomorrow morning — floors and sills for children, troughs for clearance, common-area floors for the neighbor's unit, dripline for exterior chips.
- Living areas and common areas tell you whom you are protecting while you set containment (later chapters).
You still do not collect the wipes. You do recognize a loaded trough, a gritty hallway, a painted stair that dumps dust into a living area, and chips in the dripline before the inspector's visual makes them your reclean.
On or after January 12, 2026, how do window troughs fit into dust-lead hazards versus post-abatement action levels?
Under 40 CFR 745.223, which statement about common areas is correct for a supervisor on a multi-family abatement?
After exterior paint abatement, a visual inspection finds paint chips on the dripline and next to the foundation below the abated wall. What does 40 CFR 745.227(e)(8)(v)(C) require?