Construction Glossary
Definitions with numbers in them — each term links to the calculators where it actually does work.
#57 Stone
Clean, washed crushed stone graded roughly ¾ to 1 inch with no fines — the standard drainage aggregate. Used i…
AWG (American Wire Gauge)
The US standard for wire diameter — smaller numbers mean thicker wire. Residential circuits pair 15A breakers …
Aggregate Base
Dense-graded crushed stone layer between subgrade and pavement that spreads wheel loads. Compacts to roughly 1…
BTU
British Thermal Unit — the heat to raise one pound of water 1°F, and HVAC's sizing currency. Cooling loads run…
Bank Volume
Volume of soil or rock measured in its undisturbed natural state before digging. Excavation pay quantities are…
Bitumen
The black petroleum binder that glues aggregate into asphalt, making up 4–7% of hot mix by weight. Bitumen is …
Board Foot
Hardwood lumber's volume unit: 144 cubic inches, equivalent to a 1-inch-thick board one foot square. Computed …
California Bearing Ratio (CBR)
Penetration test rating subgrade strength against crushed rock at 100. Soft clays run CBR 2–5, good granular s…
Compaction
Mechanical densification of soil, aggregate, or asphalt by rolling or tamping. Fresh asphalt loses 8–12% of it…
Crusher Run
Crushed stone with fines included (also called dense-graded base), which locks tight under compaction. The wor…
Cubic Yard
The volume unit of American bulk construction: 27 cubic feet, a cube one yard per side. Concrete, mulch, topso…
Frost Line
Maximum depth to which ground freezes in winter, from a few inches in the South to 5+ feet in the northern sta…
Geotextile Fabric
Permeable synthetic fabric separating soil layers while passing water. Under base stone it stops aggregate pun…
Grain (Water Hardness)
Unit of dissolved calcium and magnesium: one grain per gallon equals 17.1 ppm. US water runs from soft (<3.5 g…
Hot Mix Asphalt (HMA)
Asphalt concrete produced at 300–350°F by coating graded aggregate with bitumen binder. Compacted density is a…
Joist Span
The distance a horizontal framing member can bridge, set by species, grade, size, spacing, and load tables in …
Kilowatt-Hour
Energy of one kilowatt flowing for one hour — the billing unit of electricity. A solar array's monthly product…
Level 4 Finish
Drywall finishing standard (of levels 0–5) for painted walls: tape embedded, two coats over joints, fasteners …
Manual J
ACCA's residential load-calculation standard — the room-by-room heat gain/loss method behind proper HVAC sizin…
Mil
One thousandth of an inch — the thickness unit of coatings and films. Garage epoxy systems build about 10 mils…
NEC (National Electrical Code)
NFPA 70, the model electrical code adopted across the US. Sets conductor ampacity, 40% conduit fill limits, de…
Nitrogen Analysis (N-P-K)
The three numbers on fertilizer bags: percent nitrogen, phosphate, potash by weight. Lawn programs dose by rea…
On-Center Spacing (OC)
Distance between the centers of repeating framing members — studs, joists, rafters, fence posts. Standard wall…
Pattern Repeat
The vertical distance before a wallpaper motif repeats. Large repeats force alignment cuts that waste up to 15…
Peak Sun Hours
Daily solar energy expressed as equivalent full-intensity hours (1 kW/m²). The US ranges from about 3.5 in the…
Pitch Multiplier
Factor converting a building's flat footprint into true sloped roof area, equal to √(1+(rise/12)²). A 6:12 roo…
Portland Cement Concrete
The rigid paving and structural material: portland cement, sand, coarse aggregate, and water, ordered by the c…
Proctor Density
Laboratory reference for soil compaction (ASTM D698 standard / D1557 modified). Field compaction is specified …
R-Value
Resistance to heat flow through a material — higher means better insulation. Fiberglass batts deliver about R-…
RAP (Reclaimed Asphalt Pavement)
Milled or crushed old asphalt reused in new mix or as base material. Modern plants routinely run 20–30% RAP, r…
Rebar
Deformed steel reinforcing bar cast into concrete to carry tension the concrete cannot. Sized in eighths of an…
Riser and Tread
A stair's vertical step height (riser) and horizontal depth (tread). US residential code caps risers at 7¾ inc…
Roofing Square
Roofing's area unit: 100 square feet of roof surface. Shingles ship three bundles to the square; roofing labor…
Sealcoat
Protective coal-tar or asphalt-emulsion film applied over cured asphalt to block UV oxidation and water. Appli…
Short-Load Fee
Surcharge ready-mix plants add to concrete orders below their economic minimum, typically under 4 cubic yards …
Sonotube
Trade name for cylindrical cardboard concrete forms used for deck piers and columns, sized by diameter. A 12-i…
Superpave
SUperior PERforming Asphalt PAVEments — the national mix design system that replaced the Marshall method in th…
Swell Factor
The percentage a material expands when excavated from its natural bank state. Sand swells 10–15%, common earth…
Tack Coat
Thin sprayed emulsion layer that bonds successive asphalt lifts into one monolithic slab. Applied at 0.04–0.07…
Thinset vs. Mastic
The two tile adhesives: cement-based thinset for floors, wet areas, and large tile; premixed organic mastic on…