OBC House Exam cheat sheet

Model codes (IBC, IRC, IEBC, IMC, IPC, NEC/NFPA 70) become enforceable only when adopted by the local jurisdiction, often with amendments.

Occupancy classification drives allowable height, area, egress, and fire protection; mixed uses require either separated occupancies or a calculated allowable-area method.

Type of construction (I-A through V-B) sets permitted building height, number of stories, and fire-resistance ratings for structural elements.

Building area limits are set by Table 506.2; frontage increase is allowed for yards abutting public ways or open space.

A change of occupancy triggers compliance review under the International Existing Building Code, including egress and fire-resistance checks.

Permits are required before construction, alteration, or demolition; work without a permit is a code violation subject to stop-work orders.

The code official has authority to interpret code provisions and may require tests or engineering analysis to demonstrate compliance.

Variance and appeal requests generally go to a board of appeals, not to the inspector who issued the denial.

Dead load is the self-weight of structure and fixed finishes; live load is occupancy and use load per ASCE 7 Chapter 4.

Load combinations per ASCE 7 use 1.2D + 1.6L for basic strength design and include wind, seismic, and snow terms.

Soil bearing capacity must be verified by geotechnical report; presumptive values in code are minimums when no test data exist.

Footings must extend below the frost line or be designed for frost heave; depth varies by region and soil type.

Continuous footings require reinforcement sized for bending and must bear on undisturbed or compacted soil.

Lateral load resistance comes from shear walls, braced frames, or moment frames; collectors and diaphragms must be continuous to the foundation.

Wood framing: notches in the tension edge of a joist are limited, and holes must be located away from the top and bottom edges.

Concrete strength is verified by cylinder tests at 28 days; low breaks may require core testing or structural evaluation.

The building envelope must control bulk water, capillary action, air movement, vapor diffusion, and thermal transfer.

Water-resistive barriers must be shingled so upper courses lap over lower courses, and penetrations must be flashed.

Flashing is required at roof-wall intersections, valleys, chimneys, window heads, sills, and thresholds exposed to weather.

A continuous air barrier reduces uncontrolled infiltration and must be sealed at joints, penetrations, and transitions.

Vapor retarder placement depends on climate: on the warm side in cold climates, and generally omitted or vapor-permeable in hot-humid walls.

Roof slope determines roofing type; low-slope roofs below 3:12 use membrane systems, while steep-slope roofs use shingles or tiles.

Weep holes and a drainage plane behind masonry veneer allow moisture to escape and prevent trapped water damage.

Condensation risk is evaluated by comparing dew point location with the assembly's thermal and vapor profile.

HVAC sizing follows Manual J for load calculation, Manual S for equipment selection, and Manual D for duct design.

Duct leakage in unconditioned space wastes energy; ducts should be sealed and insulated to the required R-value.

Combustion appliances need adequate combustion air; direct-vent appliances draw air from outdoors.

Electrical service size depends on calculated demand load; the NEC provides demand factors for dwellings and commercial occupancies.

GFCI protection is required in bathrooms, kitchens, garages, outdoors, and near sinks; AFCI protection is required on dwelling branch circuits.

Bonding and grounding must connect metallic piping and equipment to the grounding electrode system to clear faults.

Plumbing fixtures require traps, venting, and proper slope on horizontal drains; DWV systems must maintain trap seals.

Water heater temperature and pressure relief valves must discharge to a safe location and never be capped.

Means of egress has three parts: exit access, exit, and exit discharge; each must be continuous and unobstructed.

Egress width is based on occupant load multiplied by a capacity factor, typically 0.2 inches per occupant for level components.

Two exits are generally required when occupant load exceeds the threshold for the occupancy, or where travel distance is excessive.

Exit signs and emergency lighting are required along the means of egress, and illumination must be maintained during power loss.

Fire-resistance-rated assemblies use listed materials and must be inspected; penetrations require listed firestop systems.

Sprinkler systems are governed by NFPA 13; residential systems by NFPA 13R, and they may allow area and height increases.

Smoke alarms and carbon monoxide alarms are required in dwellings and must be interconnected where required by code.

Fire extinguishers must be selected by hazard class (A, B, C, D, K) and mounted with proper travel distance to the hazard.

The energy code (IECC or ASHRAE 90.1) sets minimum envelope, lighting, and mechanical efficiency requirements.

Prescriptive path uses tables of R-values, U-factors, and fenestration limits; performance path uses whole-building energy modeling.

Building envelope air leakage is verified by blower door testing in many jurisdictions; targets are expressed in ACH50.

Duct leakage testing may be required; leakage is measured in CFM25 per 100 square feet of conditioned floor area.

Lighting power density limits are set in watts per square foot by space type; controls such as occupancy sensors are required.

HVAC equipment efficiency is rated by SEER, HSPF, or AFUE for residential systems and by COP or kW/ton for commercial.

Renewable energy and solar-ready provisions may be triggered by code adoption, project size, or jurisdiction.

Commissioning verifies that installed systems perform per design intent; it is required for larger commercial projects.

Accessible routes must be at least 36 inches clear width and have a maximum running slope of 1:20 without handrails.

Ramps require landings at top and bottom, edge protection, and handrails when the rise exceeds six inches.

Accessible parking requires a van-accessible space with an access aisle; signage must be mounted at the required height.

Door clear width in an accessible route is 32 inches minimum clear, with maneuvering clearance on both sides.

Accessible bathrooms require grab bars, turning space, and a lavatory with knee and toe clearance.

Occupant load is calculated by dividing floor area by the occupant load factor for the use and then rounding up.

Assembly occupancies have special requirements for aisle width, seating, and egress capacity.

Accessible means of egress may require areas of refuge or an accessible route in multi-story buildings.

Concrete is specified by compressive strength at 28 days, air content for freeze-thaw resistance, and slump for workability.

Reinforcement must have specified cover to protect against corrosion; cover varies with exposure conditions.

Wood framing members are graded for species and grade; moisture content affects shrinkage and strength.

Masonry walls require mortar joint size control and reinforcement or anchors for lateral stability.

Steel connections are either bolted or welded; bolt torque and weld inspection are required for structural connections.

Roof and floor sheathing must be installed with proper panel orientation, spacing, and fastening per manufacturer instructions.

Gypsum board assemblies achieve fire ratings based on layer count, thickness, and fastener spacing.

Fasteners must be compatible with treated wood; galvanized or stainless fasteners are required for preserved lumber.

Plan review checks code compliance before permit issuance; deficiencies must be corrected before approval.

Required inspections typically include footing, foundation, framing, rough-in, insulation, and final inspections.

Concrete placement requires inspection of forms, reinforcement, and embedments before the pour.

Framing inspection verifies member size, spacing, connections, and fireblocking before covering.

Rough-in inspections for plumbing, mechanical, and electrical occur before concealment by insulation or drywall.

Tests include water line pressure tests, drain line water or air tests, and duct leakage testing.

Special inspections are required for certain structural work and must be performed by qualified inspectors.

Final inspection confirms that all permitted work is complete, tested, and consistent with the approved plans.

Adopted code edition governs the project; later editions do not apply retroactively unless adopted.

Certificate of occupancy is issued after final inspection confirms compliance with the approved scope.

Fire-resistance ratings are expressed in hours and apply to structural members, shafts, and separations.

Occupancy separation requirements depend on the hazard levels of adjacent uses.

Accessibility provisions are enforced through the same permit and inspection process as other code requirements.

Deflection limits are set by code and material standards; excessive deflection can crack finishes.

Expansive soils require special foundation design, often with deepened footings or post-tensioned slabs.

Retaining walls must be designed for lateral earth pressure plus surcharge loads.

Anchor bolts transfer uplift and shear from the structure to the foundation.

Snow drift loads accumulate against parapets and taller adjacent roofs.