Roofing
What this domain tests
The Roofing domain checks whether you can read a roof, pick a covering its slope will actually accept, and stack the layers and flashing in the right order. Expect items on slope and pitch math, underlayment and ice-dam placement, shingle fastening, step and counterflashing, attic ventilation, material takeoffs, and fall protection while working at the edge.
Slope and pitch are not the same thing
Slope is rise over run, expressed against 12: a 6:12 roof rises 6 in. for every 12 in. of horizontal run. Pitch is rise over span, written as a fraction: that same roof has a 12 ft run and a 24 ft span, so its pitch is 6/24, or 1/4. Asphalt shingles require a minimum 2:12 slope; between 2:12 and 4:12 they need a double layer of underlayment, and below 2:12 you switch to a low-slope membrane.
Stacking the assembly
Underlayment runs shingle-fashion from the eave, upper courses lapping the lower, with roughly 2 in. side laps and 6 in. end laps. Ice-dam membrane extends at least 24 in. inside the interior wall line. At the eave the drip edge goes under the underlayment; at the rake it goes over. Step flashing at a sidewall is woven with each shingle course, never installed as one continuous strip.
Fastening
Three-tab shingles take four nails, six where wind exposure calls for it, driven flush within the nail zone just above the exposure line and about 1 in. from each end. Overdriving tears the mat and is a defect, not a shortcut.
Worked example
A gable roof is 40 ft long with a 20 ft run on each side at 6:12. The slope factor is the square root of (1 + 0.5 squared) = 1.118, so slope length = 20 x 1.118 = 22.4 ft. Area = 2 x 40 x 22.4 = 1,792 sq ft, about 18 squares. Applying 10 percent waste gives 20 squares; at three bundles per square, order 60 bundles. Note the trap: using the 20 ft plan run instead of the 22.4 ft slope length undercounts the roof.
Traps that cost marks
Treating pitch and slope as interchangeable; forgetting the eave drip edge belongs under the underlayment; nailing outside the nail zone or overdriving; and specifying shingles below their minimum slope.