DeckMath

13 calculators · IRC 2021 · Free forever

Maintain or upgrade

Cost and material calculators for keeping an existing deck — stain coverage, sealer estimation, power-washing cost, refinishing vs resurfacing decisions, and demolition pricing if it's time to start over. Plus drainage to extend any deck's life.

Should I refinish or rebuild my deck?

Refinish if the structure (joists, beams, footings) is sound and only the deck boards or stain are weathered. Rebuild if there's rot in the framing, the ledger is failing, footings are heaving, or the deck no longer meets current IRC code. The Resurface vs Rebuild Calculator quantifies the crossover.

13 calculators

Refinish, restore, or tear down?

Deck Stain Calculator

How many gallons of stain — real surface-area model, 13 brands (Cabot, Behr, Olympic, Defy), wood absorbency, stocked-size bundle.

Live7K searches/mo

Deck Sealer Calculator

Coverage + cost engine for clear deck sealers. Thompson's WaterSeal, Olympic, Cabot, Penofin Marine, Behr, Ready Seal. Surface condition + method + multi-year maintenance schedule. 2026 pricing.

Live3K searches/mo

Deck Paint Calculator

Gallons + cost + coats for painting a deck. 5 paint types (acrylic P&F, oil-alkyd, elastomeric, solid stain, anti-slip) × 5 condition tiers. Paint-vs-stain 5-yr TCO comparison.

Live3K searches/mo

Deck Coats & Coverage Calculator

Per-coat gallons math across 10 brands × 6 product types — Behr, Sherwin, Cabot, Ready Seal, Olympic, Thompsons. Wood-porosity multiplier on 1st coat + sealed-surface ramp on subsequent coats. 2026 retail.

Live3K searches/mo

Stain Coverage Calculator

Accurate gallons calc for deck stain — 5 opacity tiers × 7 wood species × 4 age tiers × 4 prep states × 4 application methods. Multiplier transparency panel shows exactly what's reducing yield.

Live3K searches/mo

Power Wash Cost Calculator

DIY vs contractor deck pressure-washing cost. 5 PSI tiers (electric 1500 → gas 4000+), 5 chemicals (oxygen / bleach / stripper / brightener), 5 condition tiers. Recommend right washer for condition + sqft.

Live2K searches/mo

Deck Refinishing Cost Calculator

Phase-by-phase deck refinishing cost: power-wash + strip + sand + brighten + apply. 5 current × 4 new finishes × 3 conditions. DIY material + pro full-service + hybrid. 2026 regional pricing.

Live5K searches/mo

Deck Resurfacing Cost Calculator

Resurface existing deck (keep frame, replace boards/railings) vs full rebuild. 7 decking materials × 3 fastener systems × 5 railing actions. Structural-viability check + 25-yr lifecycle TCO + sale recoup delta.

Live4K searches/mo

Deck Demolition Cost Calculator

Full cost to remove an existing deck. Labor + dumpster (10/20/30/40 yd³) OR junk-removal flat fee + tipping + permits + lead/asbestos hazard testing. 5 substructure types × 5 footing systems × 9 railing systems.

Live4K searches/mo

Resurface vs Rebuild Calculator

Head-to-head resurface vs rebuild — keep framing vs full tear-down. 8 board materials × 4 framing conditions. 25-yr lifecycle cost. Framing-condition-driven recommendation. 2026 retail.

Live3K searches/mo

Below-Deck Drainage Calculator

Standalone below-deck drainage sizing — Trex RainEscape / TimberTech DrySpace / Zip-UP UnderDeck / DeckDrain / DIY EPDM. BoM per system + ceiling lighting + ROI. Convert under-deck to finished space.

Live2K searches/mo

Deck Drainage Calculator

Above-deck (board gap + slope) AND under-deck (Trex RainEscape, TimberTech DrySpace, Zip-UP). IRC R507.2.4 compliance, drainage capacity, 5-system comparison.

Live2K searches/mo

Deck Cover/Roof Calculator

Deck cover cost across 6 types — open pergola, louvered (Struxure/Equinox), retractable awning, gable roof, lean-to, polycarbonate. Dead-load check vs deck capacity. 2026 retail.

Live4K searches/mo

Frequently asked

About this path

How often should I stain or seal a deck?
Pressure-treated lumber needs sealing every 1–3 years and staining every 3–5 years. Cedar needs sealing every 2–3 years to keep its color. Composite and PVC need only periodic washing — no sealing, ever.
How much stain do I need for my deck?
Most penetrating stains cover 200–400 sqft per gallon depending on wood porosity. For new pressure-treated lumber expect closer to 200 sqft/gal because the wood absorbs heavily. The Stain Coverage Calculator gives you a precise count by brand.
When is it cheaper to demolish than refinish?
When framing repair exceeds ~40% of new-build cost, or when joists, beams, or footings show rot or movement, demolition usually wins. The Resurface vs Rebuild Calculator handles the math with your specific deck size and material.
Will adding under-deck drainage extend my deck's life?
Yes — under-deck drainage systems (Trex RainEscape, TimberTech DrySpace) keep joists dry, which is the single biggest factor in framing lifespan. Most pay back in 10–15 years by deferring framing replacement.