Subfloor Repair Material Calculator
ANA›Life Services Authority›National Calculator Authority›Subfloor Repair Material Calculator
.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; } }
Subfloor Repair Material Calculator
Estimate the materials needed to repair or replace a damaged subfloor section, including plywood sheets, construction screws, subfloor adhesive, and blocking lumber.
Repair Area Length (ft)
Repair Area Width (ft)
Plywood Thickness
1/2 inch (12.7 mm) 5/8 inch (15.9 mm) 3/4 inch (19.1 mm) — most common
Joist Spacing (in)
12 inches on center 16 inches on center 19.2 inches on center 24 inches on center
Waste / Cut Factor (%)
Plywood Sheet Cost ($/sheet, optional)
Calculate Materials
function subCalc() { var length = parseFloat(document.getElementById('sub-length').value); var width = parseFloat(document.getElementById('sub-width').value); var thickness = parseFloat(document.getElementById('sub-thickness').value); var joistSpacing = parseFloat(document.getElementById('sub-joist-spacing').value); var wastePct = parseFloat(document.getElementById('sub-waste').value); var plywoodCost = parseFloat(document.getElementById('sub-plywood-cost').value);
var errors = []; if (isNaN(length) || length 0 ft)."); if (isNaN(width) || width 0 ft)."); if (isNaN(wastePct) || wastePct 50) errors.push("Waste factor must be between 0% and 50%.");
var resultDiv = document.getElementById('sub-result'); resultDiv.style.display = 'block';
if (errors.length > 0) { resultDiv.innerHTML = 'Please fix the following:' + errors.map(function(e){ return ''; }).join('') + ''; return; }
/ ── Core Calculations ── /
// 1. Net area and area with waste var netArea = length * width; // ft² var grossArea = netArea * (1 + wastePct / 100); // ft² with waste
// 2. Plywood sheets (4×8 = 32 ft² per sheet) var sheetArea = 4 * 8; // 32 ft² var sheetsNeeded = Math.ceil(grossArea / sheetArea);
// 3. Construction screws // Industry standard: 1 screw every 6 in along edges, every 8 in in field // Simplified: ~1 screw per 0.5 ft² of subfloor (accounts for edge + field) var screwsPerSqFt = 2.0; // screws/ft² var totalScrews = Math.ceil(grossArea * screwsPerSqFt); // Screws sold in boxes of 100 var screwBoxes = Math.ceil(totalScrews / 100);
// 4. Subfloor adhesive (construction adhesive / PL Premium) // One 28-oz tube covers ~40 linear ft of bead; apply 1 bead per joist // Number of joists crossed = floor(length / (joistSpacing/12)) + 1 var joistSpacingFt = joistSpacing / 12; // convert in → ft var joistsAlongLen = Math.floor(length / joistSpacingFt) + 1; var joistsAlongWid = Math.floor(width / joistSpacingFt) + 1; // Total linear feet of adhesive bead (one bead per joist run across the width or length) var adhesiveLinFt = joistsAlongLen * width + joistsAlongWid * length; var tubeCapacityFt = 40; // ft per 28-oz tube var adhesiveTubes = Math.ceil(adhesiveLinFt / tubeCapacityFt);
// 5. Blocking / bridging lumber (2×6 or 2×8 blocks between joists at panel edges) // Panel edges perpendicular to joists need blocking every joist bay // Bays = joists - 1; each block ≈ joistSpacing inches long // We estimate blocking for the perimeter panel edges only var blocksNeeded = Math.ceil((joistsAlongLen - 1) + (joistsAlongWid - 1)); var blockLengthFt = joistSpacingFt; // each block fills one bay var blockingLinFt = blocksNeeded * blockLengthFt; // 2×6 lumber sold in 8-ft lengths var blockingPieces = Math.ceil(blockingLinFt / 8);
// 6. Optional cost estimate var costHTML = ''; if (!isNaN(plywoodCost) && plywoodCost > 0) { var totalPlywoodCost = sheetsNeeded * plywoodCost; // Rough unit costs for other materials var screwCostPerBox = 12.00; // ~$12 per 100-ct box of 2.5" screws var adhesiveCostEach = 8.50; // ~$8.50 per tube var lumberCostPer8ft = 9.00; // ~$9 per 8-ft 2×6 var totalScrewCost = screwBoxes * screwCostPerBox; var totalAdhCost = adhesiveTubes * adhesiveCostEach; var totalLumberCost = blockingPieces * lumberCostPer8ft; var grandTotal = totalPlywoodCost + totalScrewCost + totalAdhCost + totalLumberCost; costHTML = 'Estimated Material Cost' + 'Plywood$' + totalPlywoodCost.toFixed(2) + '' + 'Screws$' + totalScrewCost.toFixed(2) + '' + 'Adhesive$' + totalAdhCost.toFixed(2) + '' + 'Blocking Lumber$' + totalLumberCost.toFixed(2) + '' + 'Grand Total (materials)$' + grandTotal.toFixed(2) + ''; }
resultDiv.innerHTML = '### Material Estimate ' + '' + 'ItemQuantity' + 'Net Repair Area' + netArea.toFixed(1) + ' ft²' + 'Gross Area (with ' + wastePct + '% waste)' + grossArea.toFixed(1) + ' ft²' + 'Plywood Sheets (4×8, ' + (thickness === 0.5 ? '1/2"' : thickness === 0.625 ? '5/8"' : '3/4"') + ')' + sheetsNeeded + ' sheets' + 'Construction Screws (2½" coarse)' + totalScrews + ' screws (' + screwBoxes + ' box' + (screwBoxes !== 1 ? 'es' : '') + ' of 100)' + 'Subfloor Adhesive (28-oz tubes)' + adhesiveTubes + ' tube' + (adhesiveTubes !== 1 ? 's' : '') + '' + 'Blocking Lumber (2×6, 8-ft pieces)' + blockingPieces + ' piece' + (blockingPieces !== 1 ? 's' : '') + ' (' + blockingLinFt.toFixed(1) + ' lin ft)' + costHTML + ''; }
#### Formulas Used
Net Area: Length (ft) × Width (ft)
Gross Area: Net Area × (1 + Waste% ÷ 100)
Plywood Sheets: ⌈Gross Area ÷ 32⌉ (one 4×8 sheet = 32 ft²)
Screws: ⌈Gross Area × 2 screws/ft²⌉ → boxes of 100 (6-in edge / 8-in field spacing)
Adhesive Tubes: ⌈Total Joist Bead Length ÷ 40 ft/tube⌉ (28-oz tube covers ~40 lin ft)
Joist Bead Length: (⌊L ÷ s⌋ + 1) × W + (⌊W ÷ s⌋ + 1) × L where s = joist spacing (ft)
Blocking Pieces: ⌈Total blocking linear ft ÷ 8⌉ (2×6 in 8-ft lengths)
#### Assumptions & References
- Standard plywood panel size is 4 ft × 8 ft (32 ft²) per APA – The Engineered Wood Association.
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