Doors, windows & glazing: NASCLA Commercial General Building Practice Questions

A fire door assembly has a label. What must happen if the door, frame or hardware is altered in the field (for example, by cutting a new hole for hardware)?

Fire door assemblies are tested as a unit; NFPA 80 limits field modifications, and unlisted changes can void the rating.

Which features are generally required on a swinging fire door?

A fire door works only if it closes and latches; hold-opens are allowed only if they release automatically on fire alarm or smoke detection.

A fire barrier has a 2-hour rating. What rating does a door opening in it typically need?

Opening protectives are usually rated below the wall: 2-hour walls get 90-minute doors, 1-hour walls 60-minute doors (45 minutes in some partitions).

What minimum clear opening height does the IBC generally require for a means of egress door?

Egress doors need 80 inches of clear height (door stops and closers may project slightly lower within limits) and 32 inches of clear width.

When must an egress door swing in the direction of egress travel?

Doors serving 50 or more people (or Group H) must swing outward with the flow so a crowd cannot pin them shut.

Panic hardware is generally required on egress doors that have latches in which situation?

Panic hardware lets a crowd open a latched door by pushing; it is required in assembly and educational spaces of 50 or more, high-hazard occupancies and some electrical rooms.

What kind of door hardware is required on an accessible door?

Lever handles, push-pull hardware and panic bars meet the accessible operation rule; round knobs do not.

How many hinges (butts) does a typical 7 ft 0 in commercial door leaf usually get?

Common practice is one hinge for each 30 inches of door height or part of it: 3 for doors up to 90 inches, plus one for each additional 30 inches.

Hollow metal doors and frames are specified by steel gauge. Which is heavier-duty?

Lower gauge numbers are thicker steel; heavy-use doors and frames often call for 16 or 14 gauge.

Why is a hollow metal frame in a masonry wall filled with grout or anchored with masonry anchors as the wall goes up?

Frames are set plumb and braced, then built in with anchors at each jamb; grouting adds strength and sound control.

Under the IBC, which location is generally a hazardous location that requires safety glazing?

People push on or walk into glass in and beside doors; the code lists these and other hazardous locations (wet areas, large low panes, guards, stairs).

How does tempered glass break, and why is it used as safety glazing?

Heat treatment puts the surfaces in compression; when it breaks, it dices. Laminated glass is the type held together by an interlayer.

Which glass type stays in the opening after breaking because its pieces stick to an interlayer?

Laminated glass bonds layers with a plastic interlayer (such as PVB); it is used overhead, in guards and for security.

Can tempered glass be cut to size in the field?

Cutting tempered glass releases its stresses and shatters it, so accurate field measurements are needed before ordering.

What does a lower U-factor mean for a window?

U-factor is the rate of heat flow; lower is better for insulation. Solar heat gain coefficient (SHGC) measures how much solar heat comes through.