Roofing, Thermal and Moisture Protection
This domain covers keeping water and heat where they belong. Understand roof slope (rise over run) and the difference between low-slope (under 3:12) and steep-slope roofs. Know common steep-slope materials (asphalt shingles, tile, metal, wood) and low-slope systems (built-up, modified bitumen, single-ply like TPO/EPDM). Understand underlayment, flashing (step, apron, valley), drip edge, and ice-and-water shield requirements in cold climates.
Master thermal protection: insulation types (batt, blown, rigid, spray foam), R-value (resistance to heat flow - higher is better), and U-factor (overall heat transfer - lower is better). Understand the building envelope and the vapor barrier/retarder - the rule is warm-side placement in cold climates (or use a smart retarder). Know ventilation (soffit and ridge vents) to prevent condensation and ice dams.
Understand waterproofing vs. dampproofing: waterproofing resists hydrostatic pressure; dampproofing resists soil moisture only. Know drainage plane and weather-resistive barrier (WRB) behind siding.
Worked rule of thumb: Roof slope 4:12 means 4 in rise per 12 in run = 33.3% slope. To find roof area from plan area, multiply by the slope factor: for 4:12, factor ≈ 1.054; for 6:12, ≈ 1.118; for 12:12, ≈ 1.414. A 2,000 sq ft plan at 6:12 needs about 2,236 sq ft of roofing.
Traps: confusing R-value and U-factor; putting vapor barrier on the cold side; using dampproofing where waterproofing is needed; ignoring slope factors in material takeoff.