Construction Glossary
Plain-English definitions for every term you'll encounter when estimating materials.
B
- Board Footlumber
- A unit of lumber volume equal to 144 cubic inches (a board 1 inch thick, 12 inches wide, and 12 inches long). Board feet = (thickness × width × length) ÷ 12, where thickness and width are in inches and length is in feet.
C
- Cubic Yardconcrete
- A unit of volume equal to 27 cubic feet (3 ft × 3 ft × 3 ft). The standard unit for ordering ready-mix concrete, gravel, and mulch in the United States.
- Concrete Bag Yieldconcrete
- The mixed volume a single bag of dry concrete produces: 80-lb bag ≈ 0.60 ft³; 60-lb bag ≈ 0.45 ft³; 40-lb bag ≈ 0.30 ft³. Divide total cubic feet by yield to find bag count.
- Coverage Ratepaint
- The area a gallon of paint covers in one coat, typically 350–400 ft² for flat finishes on smooth drywall. Rough or porous surfaces reduce coverage to 200–300 ft².
- Compacted Depthgravel
- The depth of aggregate after it has been tamped or rolled into place. Gravel typically compacts 15–20%, so order 15–20% more material than the finished depth suggests.
J
- Joist Spanframing
- The unsupported horizontal distance a joist must bridge. Maximum span depends on species, grade, size, and load. A 2×10 Douglas Fir at 16" OC typically spans 17 ft for residential floor loads.
L
- Linear Footlumber
- A one-dimensional measurement of length equal to 12 inches. Used to price fence pickets, trim lumber, and pipe without regard to width or thickness.
O
- On Center (OC)framing
- The distance from the center of one structural member to the center of the next. Standard joist and stud spacing is 16" OC; some applications use 12" or 24" OC.
R
- Roofing Squareroofing
- One roofing square equals 100 square feet of roof surface. Shingles are typically sold by the square. Three bundles of standard architectural shingles cover one square.
- Roof Pitchroofing
- The steepness of a roof expressed as rise over run — the vertical rise in inches for every 12 inches of horizontal run. A 6/12 pitch rises 6 inches per foot of horizontal distance.
- R-Valueinsulation
- A measure of thermal resistance — how well a material resists heat flow. Higher R-value = better insulation. Code minimums vary by climate zone: attics typically R-38 to R-60, walls R-13 to R-21.
W
- Waste Factorgeneral
- An additional percentage of material added to account for cuts, breakage, and sub-grade variation. Typical values: 5% for gravel, 10% for concrete and tile (straight), 10–15% for flooring, 15–20% for diagonal tile.