IDFX Building Codes and ADA 2 — Questions and Answers

Question 1: IBC Section 1004 defines 'occupant load' for egress purposes. For a business occupancy (Group B), what is the occupant load factor per person?

100 gross square feet per person
150 gross square feet per person (Correct answer)
200 gross square feet per person
50 net square feet per person

Correct answer: 150 gross square feet per person

IBC Table 1004.5 assigns an occupant load factor of 150 gross square feet per occupant for business occupancies (Group B offices). This means a 3,000 SF office has an assumed occupant load of 20 persons for egress calculations.

IBC 2021 Table 1004.5 occupant load factors (gross SF/person): Business: 150; Mercantile (ground floor): 60; Assembly (concentrated seating): 7 net SF/person; Assembly (standing): 5 net SF/person; Educational classroom: 20 net SF/person; Healthcare inpatient: 240; Storage: 300. Some occupancies use net SF (actual usable area); others use gross SF. The occupant load determines the minimum number of means of egress (OL 1-499 requires 2 exits; OL 500-999 requires 3 exits; OL 1,000+ requires 4 exits under IBC Section 1006).

Question 2: Under ADA Standards, what is the maximum slope allowed for an accessible ramp?

1:10 (10%)
1:12 (8.33%) (Correct answer)
1:16 (6.25%)
1:20 (5%)

Correct answer: 1:12 (8.33%)

ADA Standards Section 405.2 limits accessible ramp running slope to a maximum of 1:12 (one inch of rise per 12 inches of horizontal run, or 8.33%). Steeper slopes are not ADA-compliant for accessible routes.

ADA Section 405 (Ramps): Maximum running slope: 1:12; maximum cross slope: 1:48; maximum rise per run: 30 inches; minimum width: 36 inches clear between handrails; handrails required on both sides if rise exceeds 6 inches; level landing required at top and bottom (minimum 60 by 60 inches); handrail height: 34-38 inches AFF; ramp edge protection required. In existing facilities, IBC Section 1012 and ADA allow 1:10 slopes where space constraints exist, with a maximum 6 inch rise at that slope. For new construction, 1:12 is the absolute maximum.

Question 3: According to IBC Section 1010.1.9, at what maximum height above the finished floor may a door hardware operating mechanism be mounted?

44 inches AFF
48 inches AFF (Correct answer)
52 inches AFF
54 inches AFF

Correct answer: 48 inches AFF

IBC Section 1010.1.9 and ADA Section 309.4 both require door hardware (handles, pulls, latches, locks) to be mounted no higher than 48 inches above the finished floor to be within the reach range of wheelchair users.

ADA Section 308 (Reach Ranges): Forward reach (unobstructed): max 48 inches AFF; side reach (unobstructed): max 48 inches AFF; obstructed forward reach over a counter: if obstruction depth 20 inches or less, max 48 inches AFF; if 20-25 inches deep, max 44 inches AFF. Door hardware must also be operable without tight grasping, pinching, or twisting of the wrist — lever handles, push plates, and loop pulls comply; round knobs do not. IBC Section 1010.1.9.1 additionally requires panic hardware (exit devices) to be mounted between 34 and 48 inches AFF on exit doors in Group A, B, E, and M occupancies.

Question 4: Which IBC occupancy classification applies to a nail salon?

Group A-2 (Assembly)
Group B (Business) (Correct answer)
Group M (Mercantile)
Group S-1 (Storage)

Correct answer: Group B (Business)

Nail salons, beauty salons, and similar personal service establishments are classified as Group B (Business) occupancies under IBC Section 304, which covers professional services, civic uses, and personal service businesses not primarily retail in nature.

IBC Occupancy Classifications relevant to commercial interior design: Group A (Assembly, OL 50+): restaurants (A-2), theaters (A-1), gyms (A-3); Group B (Business): offices, banks, barber/beauty shops, nail salons, outpatient clinics; Group E (Educational): schools; Group I (Institutional): hospitals (I-2), nursing homes (I-2); Group M (Mercantile): retail stores, markets, showrooms where merchandise is displayed and sold; Group R (Residential). The distinction between B and M is important: the mercantile classification triggers different fire suppression requirements, occupant load factors (60 SF/person vs. 150 SF/person), and sprinkler thresholds.

Question 5: What is the minimum number of accessible parking spaces required for a parking lot with 75 total spaces per ADA Standards Table 208.2?

2 spaces
3 spaces (Correct answer)
4 spaces
5 spaces

Correct answer: 3 spaces

ADA Standards Table 208.2 requires 3 accessible parking spaces for a lot with 51-75 total spaces (1 for 1-25 spaces, 2 for 26-50, 3 for 51-75, 4 for 76-100).

ADA Table 208.2 accessible parking requirements: 1-25 total spaces = 1 accessible; 26-50 = 2; 51-75 = 3; 76-100 = 4; 101-150 = 5; 151-200 = 6; 201-300 = 7; 301-400 = 8; 401-500 = 9; 501-1000 = 2% of total; 1001+ = 20 + 1 per 100 over 1000. Of the required accessible spaces, at least 1 in every 6 must be van-accessible (8-foot-wide space + 8-foot-wide aisle, or 11-foot-wide van space + 5-foot aisle). Van-accessible spaces must have 98 inch vertical clearance along the accessible route.

Question 6: The IBC 'means of egress' system consists of three sequential components. Which is the correct sequence from exit access to exit discharge?

Exit access, exit passageway, public way
Exit access, exit, exit discharge (Correct answer)
Exit corridor, exit stair, exit lobby
Occupied space, fire corridor, exterior door

Correct answer: Exit access, exit, exit discharge

IBC Section 1003 defines the three components of means of egress: (1) Exit access — the portion leading from the occupied space to the exit; (2) Exit — the protected path (enclosed stair, exterior door, horizontal exit); (3) Exit discharge — the path from the exit to the public way.

IBC Means of Egress components: Exit access (Section 1017): unprotected portion — occupied spaces, corridors, aisles leading to an exit; Exit (Section 1022): protected, enclosed, fire-rated components — exit enclosures (stairs, ramps), exit passageways, exterior exit stairways, horizontal exits, exterior exit doors at grade; Exit discharge (Section 1028): portion leading from exit termination to the public way. The exit enclosure requires fire-resistance rating of 1 hour (floors 1-3 stories) or 2 hours (4+ stories). Exit discharge must be at grade or lead directly to grade, with safe access to a public way.

IDFX Building Codes and ADA 2

IBC Section 1004 defines 'occupant load' for egress purposes.
For a business occupancy (Group B), what is the occupant load factor per person?