Guides
Plain-language trade math, written to be actually useful.
Every guide pairs with a calculator on this site, and every number comes from a published table or code rule — not an estimate. Use the tool for your build, then read the guide to understand the math behind it and where the rules come from.
Concrete Slab Thickness & How Much Concrete You Need
How thick a slab should be (IRC minimum plus practice by use), the volume formula, waste, and bags vs. ready-mix.
Read →Concrete Curing Time: When You Can Walk, Load & Seal
Walk-on, form-strip, drive-on, and full-load timings, the ACI 70% rule, and why cold weather doubles the wait.
Read →Deck Board Spacing: Why Gaps Matter
1/8″ vs 1/4″ gaps, why boards move, and how to keep spacing even.
Read →How Deep Should Mulch and Gravel Be?
Depth by material — bark 3″, chips 4″, driveway stone 4–6″ — plus the cubic-yard math and what to add for settling.
Read →Stair Math: Risers, Treads & Code Rules
IRC limits on riser height and tread depth, the 3/8″ variation rule, and a worked 105″ example.
Read →What Size Wire for a 100 Amp Subpanel?
3 AWG copper or 1 AWG aluminium to start, 2 AWG at 150 ft, 1 AWG at 200 ft — with the 83% rule trap and the ground wire size.
Read →Deck Stairs: How Many Steps & What the Code Requires
Total rise to step count, the riser and tread limits, when a landing is required, and the footing and guard rules for the bottom of the run.
Read →What Size Wire for a 200 Amp Service?
2/0 copper or 4/0 aluminium for a 200 A service under the 83% rule; 3/0 copper or 250 kcmil aluminium for a 200 A subpanel. Distance table and worked example.
Read →Deck Post Spacing: How Far Apart Should Posts Be?
Post spacing is your beam span, not a fixed number — how to read Table R507.5(1), plus post size from R507.4, footing size from R507.3.1, and the post-to-footing connection.
Read →