LICT-Interior cheat sheet

Gypsum board fire-rated assemblies: 5/8 in. Type X on each face of 3-5/8 in. steel studs with mineral wool and joint treatment yields a 1-hour rating; add a second layer per side for 2-hour ratings.

Steel stud spacing governs board span: 1/2 in. gypsum board spans 16 in. o.c. maximum for walls; 24 in. o.c. requires 5/8 in. board or ceiling-specific framing.

Ceiling height: minimum 7 ft 6 in. in habitable rooms and corridors; 7 ft 0 in. permitted in bathrooms, kitchens, and under beams and ducts in dwelling units.

Floor finish slip resistance: level floors generally 0.6 SCOF (dry) per ADA-referenced test; ramps and transitional surfaces require higher friction and contrasting detectable warnings.

Finish schedule cross-references: room number, finish code, base, wall, floor, and ceiling must match the reflected ceiling plan and door schedule; a mismatch is a common RFI source.

Acoustic separation: STC 50 for demising walls between dwelling units; achieved with double studs, resilient channels, and insulated cavities rather than single-layer board.

Tile installation: ANSI A108 series governs; large-format tile (≥15 in.) requires ≥95% mortar coverage on interior floors and 100% in wet areas per TCNA methods.

Millwork: AWI quality grades Economy, Custom, and Premium govern joinery, panel matching, and finish; specify grade and panel face sequence on drawings.

Occupant load factors (IBC Table 1004.5): business 150 gross sq ft/occupant; assembly unconcentrated tables/chairs 15 net; classroom 20 net; mercantile 60 gross; storage 300 gross.

Interior finish classes (IBC 803): Class A flame spread 0-25, Class B 26-75, Class C 76-200; smoke-developed index limited to 450 for all three.

Sprinkler credit: in fully sprinklered buildings, Class B and C wall/ceiling finishes are permitted in most occupancies where Class A would otherwise apply (IBC 803.1.2).

Corridor walls: minimum 1-hour fire-resistance in most occupancies; 0.5-hour permitted in sprinklered Group R-2 and certain B occupancies per IBC Table 1020.1.

Means of egress width: 0.2 in. per occupant for level components and ramps, 0.15 in. per occupant for stairways and other egress components (IBC 1005.3.1).

Change of occupancy: IEBC Chapter 10 requires evaluation of egress, fire protection, and accessibility; a higher-hazard classification may trigger full compliance.

Dwelling unit separation: 1-hour fire-resistance between units and between units and corridors in Group R-2; 0.5-hour permitted in sprinklered buildings in some editions.

Fire-rated door assemblies: label ratings 20, 45, 60, 90, and 180 minutes; 20-minute labels permitted only in 1-hour or less rated walls and require no hose stream test.

Door hardware: panic hardware required on egress doors in assembly and educational occupancies serving 50 or more occupants; fire-rated doors require positive latching.

Fireblocking: required in concealed spaces at floor/ceiling levels, at soffits, and where chases pass between stories; use approved materials tested to ASTM E136 or listed systems.

Firestopping: through-penetrations in rated assemblies must be sealed with listed systems (ASTM E814/UL 1479); annular space and sleeve type dictate the required system.

Smoke barriers: 1-hour minimum with smoke-tight joints; smoke partitions are not required to be rated but must limit smoke spread and be labeled as such.

Exit access travel distance: 250 ft unsprinklered and 300 ft sprinklered in most non-industrial occupancies; Group R-2 typically 125 ft / 250 ft.

Standpipe and extinguisher cabinets in rated walls: recessed cabinets require protection equal to the wall rating or listed cabinet assemblies.

Accessible route clear width: 36 in. minimum continuous; 32 in. minimum at a point (door clear width is measured with the door open 90 degrees).

Ramp requirements: maximum slope 1:12; 1:10 and 1:8 permitted only for existing site constraints with limits; landings required at top, bottom, and every 30 in. of rise.

Handrails: 34-38 in. above floor surface; extensions of 12 in. beyond top and bottom of stair flights; clearance of 1-1/2 in. from wall.

Stair geometry: riser height 4-7 in.; tread depth 11 in. minimum; nosing projection 3/4-1-1/4 in.; uniform riser and tread throughout a flight.

Door maneuvering clearances: 60 in. clear on the pull side and 36 in. on the push side, plus 18 in. on the latch side of the pull side; measured from the door face.

Accessible parking: 8 ft wide space plus 8 ft access aisle for car spaces; 11 ft space plus 5 ft aisle for van-accessible spaces; one in every six accessible spaces van-accessible.

Exit signs: illuminated, visible from any point in the path, with directional indicators where the path to the exit is not obvious; maximum viewing distance and height per code.

Concrete moisture: adhesive and resilient flooring require vapor emission ≤3 lb/1000 sq ft/24 hr (calcium chloride) and RH ≤75-80% per manufacturer; test before installation.

Gypsum board fastening: screws spaced 12 in. o.c. on ceilings and 16 in. o.c. on walls for single-layer; joints staggered and treated with setting-type compound for fire-rated assemblies.

Acoustical ceiling grid: main runners at 4 ft o.c. maximum, cross tees at 2 ft; hanger spacing 4 ft o.c. and within 8 in. of the boundary.

Ceramic tile substrate: cement backer board or approved membrane required in wet areas; deflection limit L/360 for floors and L/360 for ceilings with tile.

Paint systems: primer plus two finish coats typical; gloss level affects scrubbability; drywall joints must be sanded and primed to avoid flashing.

Carpet installation: direct glue-down, stretch-in, and modular tile methods; stretch-in requires tackless strip and power stretcher; modular requires flat substrate and acclimation.

Wood flooring: solid wood requires 3/4 in. thickness and nail-down over plywood; engineered wood permits glue-down or floating over concrete with vapor barrier.

Pre-cover inspection: framing, fireblocking, firestopping, and MEP rough-in must be inspected before gypsum board is installed; document with photos and signed inspection reports.

Firestop inspection: ASTM E2174 (through-penetration) and E2393 (joint systems) define inspection and testing of installed firestop systems.

Moisture testing documentation: record test method, date, location, and results; retain for the project record and provide to flooring manufacturer for warranty.

Punch list and substantial completion: AIA G704 Certificate of Substantial Completion defines the date, incomplete items, and warranty start.

Shop drawings and submittals: product data, samples, and mockups must be approved before installation; record approved submittal numbers on as-builts.

Final inspection: verify accessibility clearances, fire-rated hardware, exit signage, and finish schedule compliance; document with marked-up drawings and inspection reports.

Mockups: required for exterior wall assemblies and often for interior finishes; test the mockup for water, air, and finish appearance before full installation.