Plan Reading, Estimating, and Bidding
Reading the set
Every project has a drawing set: plan views, elevations, sections, details, and a legend/sheet index. Before measuring anything, find the scale (each sheet and each detail can carry its own, e.g., site plan at 1"=20' while a wall detail is 1"=1'-0"), the north arrow, benchmark, contour interval, and spot elevations. Contours close together mean steep ground; a contour V points uphill in a drainageway. Confirm whether dimensions are feet-inches or decimal feet - mixing them is the single most common arithmetic error.
Estimating vs. bidding
A takeoff is quantities by assembly: excavation, base, paving, edging, soil, plants, irrigation, and labor. Convert units before pricing (1 CY = 27 CF, 1 SY = 9 SF, 1 acre = 43,560 SF). Add waste, then overhead, profit, and contingency. An estimate predicts cost; a bid is a binding offer, so read general conditions, specifications, addenda, alternates, and allowances, and state exclusions in writing. Change orders and differing site conditions are where unbudgeted losses appear.
Worked example
A planting bed measures 3.5 inches on a 1/8" = 1'-0" plan. Since 1/8" = 1', one inch = 8 ft, so 3.5" = 28 ft. If the bed is 20 ft wide, area = 560 SF. Mulch at 3" depth: 560 × 0.25 = 140 CF ÷ 27 = 5.2 CY, plus 10% waste = 5.7 CY. Rule of thumb: 5% waste on paving, 10% on plants and mulch, 3–5% contingency.
Traps
Using the detail scale for the plan; ignoring the waste factor; forgetting that paving quantities are usually sold by the ton or square yard; and bidding without a site visit.