Structural Drying Equipment Needs Estimator

ANA›Life Services Authority›National Calculator Authority›Structural Drying Equipment Needs Estimator

.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }

Structural Drying Equipment Needs Estimator

Estimates the number of air movers and dehumidifiers required to dry a water-damaged structure based on affected square footage, material types, saturation class, and ambient conditions.

Affected Floor Area (sq ft)

Ceiling Height (ft)

Water Damage Class

Class 1 – Minimal absorption (part of room, low porosity) Class 2 – Significant absorption (entire room, carpet/pad) Class 3 – Greatest absorption (walls, ceilings, insulation) Class 4 – Specialty drying (hardwood, plaster, concrete)

Water Category

Category 1 – Clean water Category 2 – Grey water Category 3 – Black water

Current Relative Humidity (%)

Ambient Temperature (°F)

Affected Wall Area (sq ft, 0 if none)

Carpet/Pad Present in Affected Area?

No Yes

Calculate Equipment Needs Fill in all fields and click Calculate.

function sdeCalc() { var resultDiv = document.getElementById('sde_result');

// --- Gather inputs --- var area = parseFloat(document.getElementById('sde_area').value); var ceilHt = parseFloat(document.getElementById('sde_ceiling_ht').value); var waterClass = parseInt(document.getElementById('sde_water_class').value); var waterCat = parseInt(document.getElementById('sde_water_cat').value); var rh = parseFloat(document.getElementById('sde_rh').value); var temp = parseFloat(document.getElementById('sde_temp').value); var wallArea = parseFloat(document.getElementById('sde_affected_walls').value); var hasCarpet = parseInt(document.getElementById('sde_has_carpet').value);

// --- Validation --- var errors = []; if (isNaN(area) || area 30) errors.push("Ceiling height must be between 6 and 30 ft."); if (isNaN(rh) || rh 100) errors.push("Relative humidity must be between 10% and 100%."); if (isNaN(temp) || temp 110) errors.push("Temperature must be between 40°F and 110°F."); if (isNaN(wallArea)|| wallArea 0) { resultDiv.innerHTML = 'Please fix the following:' + errors.map(function(e){ return ''; }).join('') + ''; return; }

// ===================================================================== // STEP 1: Air Movers // IICRC S500 Standard: 1 air mover per 10–16 sq ft of wet surface area // Base rule: 1 air mover per 10 sq ft (Class 1), scaling up by class // ===================================================================== // Class multipliers for air mover coverage (sq ft per unit) var amCoverageMap = { 1: 16, 2: 10, 3: 8, 4: 6 }; var amCoverage = amCoverageMap[waterClass];

// Total wet surface = floor + walls (walls counted at 0.5 weight for air movers // since air movers primarily address floor/horizontal surfaces) var totalWetSurface = area + (wallArea * 0.5);

// Carpet adds extra surface area factor (pad underneath doubles drying surface) if (hasCarpet === 1) { totalWetSurface = totalWetSurface * 1.25; }

var airMoversRaw = totalWetSurface / amCoverage; var airMovers = Math.ceil(airMoversRaw);

// ===================================================================== // STEP 2: Dehumidifiers // IICRC S500 / LGR method: // Volume (cu ft) = area × ceiling height // Psychrometric grain load: // Grains of moisture to remove = Volume × (GPP_current - GPP_target) // GPP (grains per pound of dry air) from temp & RH using approximation // Target RH = 40% (standard drying goal) // Dehumidifier capacity in pints/day (standard LGR unit = 150 pints/day) // Pints/day needed = grain load / 7000 × 8.34 × 24 / drying_days // Simplified IICRC formula: 1 dehumidifier per 800–1600 cu ft (class-dependent) // =====================================================================

var volume = area * ceilHt; // cubic feet

// Saturation pressure approximation (Magnus formula) → GPP // Ws (lb water/lb dry air) = 0.62198 × Pws / (P - Pws) // Pws (psia) ≈ exp(23.7836 - 4144.96/(T_rankine - 33.91)) / 144 [simplified] // GPP = Ws × 7000 function calcGPP(tempF, rhPct) { var T = tempF + 459.67; // Rankine // Antoine-style approximation for saturation pressure in psia var lnPws = 23.7836 - 4144.96 / (T - 33.91); var Pws = Math.exp(lnPws) / 144; // convert psf to psia var phi = rhPct / 100; var P = 14.696; // atmospheric pressure psia var Ws = 0.62198 * (phi * Pws) / (P - phi * Pws); return Ws * 7000; // grains per pound dry air }

var gppCurrent = calcGPP(temp, rh); var gppTarget = calcGPP(temp, 40); // target 40% RH

// Density of air ≈ 0.075 lb/cu ft at standard conditions; adjust for temp var airDensity = 0.075 * (530 / (temp + 459.67)); // lb/cu ft

// Total grains to remove from the space var totalGrains = volume * airDensity * Math.max(0, gppCurrent - gppTarget);

// Assume 3-day drying cycle (IICRC standard monitoring interval) var dryingDays = 3; var grainsPerDay = totalGrains / dryingDays;

// Convert grains/day to pints/day: 7000 grains = 1 lb water; 1 pint water = 1.04 lb var pintsPerDay = grainsPerDay / 7000 / 1.04;

// Add structural moisture load: wet materials release moisture // Class multiplier for structural load factor var structLoadMap = { 1: 1.1, 2: 1.3, 3: 1.6, 4: 1.4 }; pintsPerDay = pintsPerDay * structLoadMap[waterClass];

// Wall area adds additional evaporative load if (wallArea > 0) { // Walls contribute ~0.05 pints/day per sq ft of wet wall (empirical) pintsPerDay += wallArea * 0.05; }

// Carpet adds moisture load if (hasCarpet === 1) { pintsPerDay += area * 0.03; }

// Standard LGR dehumidifier capacity = 150 pints/day (AHAM rating ~70 pints/day // but LGR units used in restoration = 100–175 pints/day; use 150 as standard) var dehCapacity = 150; // pints/day per unit var dehRaw = pintsPerDay / dehCapacity; var dehumidifiers = Math.ceil(dehRaw); dehumidifiers = Math.max(1, dehumidifiers); // minimum 1

// ===================================================================== // STEP 3: Category adjustments // Cat 2/3 may require additional equipment for containment/negative air // ===================================================================== var negativeAirMachines = 0; var airScrubbers = 0; if (waterCat >= 2) { // 1 air scrubber per 1000 sq ft for Cat 2; 1 per 500 sq ft for Cat 3 var scrubberCoverage = (waterCat === 3) ? 500 : 1000; airScrubbers = Math.ceil(area / scrubberCoverage); airScrubbers = Math.max(1, airScrubbers); } if (waterCat === 3) { negativeAirMachines = Math.ceil(area / 1000); negativeAirMachines = Math.max(1, negativeAirMachines); }

// ===================================================================== // STEP 4: Drying time estimate // Simplified: base days by class, adjusted for RH and temp // ===================================================================== var baseDaysMap = { 1: 2, 2: 3, 3: 5, 4: 7 }; var estimatedDays = baseDaysMap[waterClass]; // High RH extends drying if (rh > 80) estimatedDays += 1; if (rh > 90) estimatedDays += 1; // Low temp extends drying (optimal 70–90°F) if (temp 95) estimatedDays += 1; // too hot also slows dehumidification

// ===================================================================== // STEP 5: Estimated daily power consumption // Air mover ≈ 5–7 amps @ 120V = ~720W each // LGR dehumidifier ≈ 7–8 amps @ 120V = ~900W each // Air scrubber ≈ 1.5–2 amps @ 120V = ~200W each // ===================================================================== var powerAM = airMovers * 720; // watts var powerDH = dehumidifiers * 900; // watts var powerAS = airScrubbers * 200; // watts var powerNAM = negativeAirMachines * 750; // watts var totalPowerW = powerAM + powerDH + powerAS + powerNAM; var totalPowerKW = (totalPowerW / 1000).toFixed(2); var dailyKWh = (totalPowerKW * 24).toFixed(1);

// ===================================================================== // Build output // ===================================================================== var classNames = { 1:"Class 1 (Minimal)", 2:"Class 2 (Significant)", 3:"Class 3 (Extensive)", 4:"Class 4 (Specialty)" }; var catNames = { 1:"Category 1 (Clean)", 2:"Category 2 (Grey)", 3:"Category 3 (Black)" };

var html = '### Equipment Estimate Results '; html += ''; html += 'EquipmentQuantityNotes';

var rows = [ ['Air Movers', airMovers, 'Axial/centrifugal, 1 per ' + amCoverage + ' sq ft wet surface'], ['LGR Dehumidifiers', dehumidifiers, '150 pints/day capacity each'], ]; if (airScrubbers > 0) rows.push(['Air Scrubbers / Negative Air', airScrubbers, 'HEPA filtration for Cat ' + waterCat + ' contamination']); if (negativeAirMachines > 0) rows.push(['Negative Air Machines', negativeAirMachines, 'Containment & pressure differential for Cat 3']);

rows.forEach(function(r, i) { var bg = i % 2 === 0 ? '#f4f8fb' : '#fff'; html += '' + '' + r[0] + '' + '' + r[1] + '' + '' + r[2] + '' + ''; }); html += '';

html += ''; html += 'Drying Conditions Summary';

var summaryRows = [ ['Damage Class / Category', classNames[waterClass] + ' / ' + catNames[waterCat]], ['Affected Floor Area', area.toLocaleString() + ' sq ft'], ['Affected Wall Area', wallArea.toLocaleString() + ' sq ft'], ['Room Volume', volume.toLocaleString() + ' cu ft'], ['Current GPP (Grains/lb)', gppCurrent.toFixed(1)], ['Target GPP @ 40% RH', gppTarget.toFixed(1)], ['Moisture Load to Remove', pintsPerDay.toFixed(0) + ' pints/day'], ['Estimated Drying Time', estimatedDays + ' days (monitored)'], ['Total Power Draw', totalPowerKW + ' kW (' + dailyKWh + ' kWh/day)'], ];

summaryRows.forEach(function(r, i) { var bg = i % 2 === 0 ? '#f4f8fb' : '#fff'; html += '' + '' + r[0] + '' + '' + r[1] + '' + ''; }); html += '';

if (waterCat === 3) { html += '' + '⚠ Category 3 (Black Water): Full containment, PPE, and antimicrobial treatment required. ' + 'Consult IICRC S500 and local health regulations before proceeding.

'; }

resultDiv.innerHTML = html; }

#### Formulas Used

Air Movers: Air Movers = ⌈(Floor Area + Wall Area × 0.5) × Carpet Factor / Coverage per Unit⌉ Coverage per unit: Class 1 = 16 sq ft, Class 2 = 10 sq ft, Class 3 = 8 sq ft, Class 4 = 6 sq ft (IICRC S500). Carpet factor = 1.25 if carpet/pad present.

Dehumidifiers: GPP = W × 7000, where W = 0.62198 × φ·Pws / (P − φ·Pws) Pws = saturation pressure (Antoine approximation), φ = RH fraction, P = 14.696 psia Total Grains = Volume × Air Density × (GPP_current − GPP_target@40%) Pints/Day = (Total Grains / 3 days) / 7000 / 1.04 × Class Load Factor + Wall Load + Carpet Load Dehumidifiers = ⌈Pints/Day / 150⌉ (LGR unit = 150 pints/day capacity)

Air Scrubbers (Cat 2/3): 1 per 1,000 sq ft (Cat 2) or 1 per 500 sq ft (Cat 3). Negative Air Machines (Cat 3): 1 per 1,000 sq ft.

Estimated Drying Time: Base days by class (1→2d, 2→3d, 3→5d, 4→7d), extended for RH >80%/90% and temperature outside 70–95°F range.

#### Assumptions & References

More Calculators

Read Next

Study Time Planner Authority Network America › Life Services Authority › National Calculator Authority .calc-container { max-width: 640px;...

References

Related Authorities

Life Services Authority › Professional Services Authority › Trade Services Authority › United States Authority ›