National Home Inspector Examination flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Joist notch limit

In solid-lumber floor joists, notches may not exceed one-sixth of the joist depth and are not permitted in the middle third of the span.

Horizontal foundation crack

Long horizontal cracks in a masonry or concrete foundation wall typically indicate lateral soil pressure or frost movement; vertical shrinkage cracks are usually narrower and less significant.

Truss field modification

Cutting, notching, or boring an engineered floor or roof truss in the field is not permitted without written approval from a design professional.

Joist bearing minimum

Wood joists need at least 1-1/2 inches of bearing on wood or metal supports and at least 3 inches of bearing on masonry.

Furnace temperature rise

The difference between return and supply air at a furnace; it must fall within the range on the manufacturer's data plate, commonly about 35 to 65 degrees Fahrenheit for gas units.

Air conditioner delta T

A central air conditioner in steady operation should deliver supply air about 15 to 20 degrees Fahrenheit cooler than the return air measured near the unit.

Condensate drain requirements

Primary condensate lines need a trap and must not drain into a crawlspace; a secondary pan drain should terminate where overflow can be seen.

Combustion air rule

Using indoor air infiltration, a gas appliance needs about 50 cubic feet of space per 1,000 BTU/h of input; otherwise dedicated outdoor combustion air is required.

GFCI required locations

Ground-fault protection is required in bathrooms, kitchens, garages, outdoors, unfinished basements, crawlspaces, and at receptacles within six feet of a sink.

Copper wire ampacity

14 AWG copper conductors are rated 15 amps, 12 AWG are rated 20 amps, and 10 AWG are rated 30 amps for standard branch-circuit use.

Subpanel neutral isolation

In a subpanel the neutral bus must be isolated from the equipment ground, and the main bonding screw must be removed so ground and neutral stay separate.

Receptacle spacing rule

Along a dwelling's walls, no point may be more than six feet from a receptacle, and any wall space two feet or wider requires one.

TPR discharge pipe rules

A water heater relief valve pipe must terminate within six inches of the floor, be full size and unthreaded, and must not be trapped or fitted with a valve.

Drain pipe slope

Drain lines two inches and smaller slope one-quarter inch per foot; three-inch and larger lines slope one-eighth inch per foot.

Water supply pressure

Residential supply pressure should be between 40 and 80 psi; a pressure-reducing valve is needed when incoming pressure exceeds 80 psi.

Dielectric union

A fitting that separates dissimilar metals such as copper and galvanized steel to prevent galvanic corrosion at the threaded connection.

Chimney 3-2-10 rule

A chimney must extend at least three feet above the roof surface where it penetrates and at least two feet above anything within ten feet.

Shingle layer limit

No more than two layers of asphalt shingles may be installed or remain on a roof; a third layer requires stripping the old roofing.

Step flashing

L-shaped metal used at roof-to-sidewall intersections, installed in courses with the shingles; kick-out flashing at the bottom diverts water away from the wall.

Ice dam membrane

Self-adhering waterproof membrane required along eaves in cold climates, extending at least 24 inches inside the exterior wall line to prevent ice-dam leakage.

Guardrail sphere rule

Openings in a guardrail must be small enough that a four-inch sphere cannot pass through; guards on residential decks are at least 36 inches high.

Handrail height

Handrails along stairs are installed 34 to 38 inches above the stair nosing, and the handrail profile must be graspable.

Siding clearance

Exterior siding should be at least six inches above finished grade and one inch above roof surfaces to prevent moisture wicking and rot.

Smoke alarm locations

Smoke alarms are installed inside each bedroom, outside each sleeping area, and on every story of the dwelling, including basements.

Garage separation wall

The wall between an attached garage and living space needs at least half-inch gypsum board, and the door must be self-closing and solid or 20-minute rated.

Egress window size

An emergency egress window needs at least 5.7 square feet of clear opening, 24 inches of height, 20 inches of width, and a sill no higher than 44 inches.

Exhaust fan discharge

Bathroom and kitchen exhaust fans must terminate outdoors through smooth duct, never into an attic, crawlspace, or other interior space.

Attic ventilation ratio

Attic vent area should equal 1/150 of the attic floor area, or 1/300 when a vapor retarder is installed; roughly half the vents are intake at the eaves.

Vapor retarder placement

The vapor retarder faces the warm side of the assembly: on the interior in cold climates and toward the exterior in hot-humid climates.

Inspection scope

A standard home inspection is a visual, non-invasive examination of readily accessible systems and components on the day of the inspection; it is not technically exhaustive.

Conflict of interest

An inspector should not repair or perform work on a property they inspected, and many states prohibit such work for 12 months after the inspection.

Reporting code compliance

Inspectors describe observed conditions, their implications, and recommended actions; they do not certify that a component complies with building codes.