Guides & Reference Tables
Our calculators give you a number. These guides explain where those numbers come from: the waste allowances built into the results, the unit conversions the trades actually use, and the code requirements that constrain them.
Material Waste Factors
Every quantity calculator gives you a geometrically perfect number, and that number will leave you short. This guide covers typical waste allowances by material, and why compaction and settling are different problems that need separate allowances.
Updated
Mortar, Grout & Core Fill
Mortar bonds the units, grout fills the cores, and standard concrete mix does neither well. This guide sets the three side by side, then works through how much of each a job takes, including why a partially grouted wall needs roughly a third of the fully grouted figure.
Updated
Paint Coverage Rates
A gallon of architectural paint is commonly labelled at 350 to 400 square feet, and that figure assumes a smooth, sealed, primed surface, one coat, applied with a roller. This guide starts with that number and then works through each condition that pulls the real rate away from it, ending with how to turn a corrected rate into cans.
Updated
Paver Base and Bedding
A paver patio is a stack of five layers, and each one can fail on its own. This guide follows the stack in the order it gets built, from the subgrade up: how deep the base goes for a patio against a driveway, which aggregate belongs in it, and why the inch of sand above it is not a levelling course.
Updated
Construction Unit Conversions
The trades measure in units that rarely match how material is sold. This is a reference for the conversions that come up most, covering cubic yards to tons, roofing squares, board feet, and bag counts, including why any yards-to-tons conversion needs the material's density.
Updated
Stair Code Requirements
The IRC caps residential risers at 7 3/4 inches and requires treads of at least 10 inches, but the rule that fails inspections most often is uniformity: no more than 3/8 inch of variation between the tallest and shortest riser in a flight.
Updated