Sources & formulas

Every calculator on RestorationCalcs rests on established arithmetic plus stable IICRC/AHAM/EPA conventions. Unlike topics with a time dependency, "verification" here is mathematical: each formula is tested against known values and is therefore correct for good. Here are the technical foundations by area.

Identities & thresholds

• Volume & water: 27 cubic feet = 1 cubic yard; 7.48 gallons = 1 cubic foot; an inch of water over a square foot is 0.623 gallons.
• Air changes: ACH = CFM × 60 ÷ room volume (cu ft); required CFM = ACH × volume ÷ 60; containment/IAQ targets 4–6 ACH.
• EPA thresholds: mold over about 10 sq ft usually needs a professional; the radon action level is 4 pCi/L.

Water & drying (IICRC)

• Category 1/2/3: how contaminated the water is (clean → gray → black).
• Class 1–4: how much water and how hard it is to dry.
• Air movers: ceil(affected sq ft ÷ ~50–70 sq ft per unit); LGR dehumidifiers: ceil(affected sq ft ÷ ~500 sq ft per unit) — labeled IICRC/AHAM typicals.

Cost tools

• Every cost tool uses the prices you enter ($/sq ft, $/ft, $/day, $/hr, $/vent, $/sample, $/point) — no restoration or labor price, no cost index is stored, so the site needs no maintenance. Cost bands are a labeled sanity guide.
• Cost: total = (affected sq ft × your $/sq ft × category/severity multiplier + Σ line items) ×(1 + contingency).
• Insurance: out-of-pocket = max(0, min(covered loss, damage) − deductible) — illustrative only.

Restoration pricing, permit rules, local code and disposal rates vary by place and change over time — always get itemized written quotes and permits from a licensed, insured, IICRC-certified restoration contractor and your local authority/insurer. Category 2/3 water, sewage and biohazard are health hazards — hire certified pros. Asbestos and lead are regulated hazardous materials (licensed abatement only).