Blown in Insulation Calculator

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Blown-In Insulation Calculator

Estimate the amount and cost of blown-in insulation needed for your attic or wall cavities. This calculator helps you determine the required R-value, thickness, and number of bags based on your chosen material and area.

Recommended R-values vary by climate zone (e.g., R-38 to R-60 for attics).
Enter 0 if starting from scratch.
Cellulose (R-3.7/inch) Fiberglass (R-2.8/inch)
Enter 0 if doing it yourself.

Calculation Results:

Total Area: — sq ft

Additional R-Value Needed: —

Required Thickness: — inches

Estimated Bags Needed: — bags

Estimated Material Cost: $–

Estimated Labor Cost: $–

Total Estimated Cost: $–

function calculateBlownInInsulation() { // Get input values var roomLength = parseFloat(document.getElementById("roomLength").value); var roomWidth = parseFloat(document.getElementById("roomWidth").value); var rValueDesired = parseFloat(document.getElementById("rValueDesired").value); var rValueCurrent = parseFloat(document.getElementById("rValueCurrent").value); var insulationType = document.getElementById("insulationType").value; var costPerBag = parseFloat(document.getElementById("costPerBag").value); var laborCostPerSqFt = parseFloat(document.getElementById("laborCostPerSqFt").value); // Validate inputs if (isNaN(roomLength) || roomLength <= 0) { alert("Please enter a valid Area Length (must be a positive number)."); return; } if (isNaN(roomWidth) || roomWidth <= 0) { alert("Please enter a valid Area Width (must be a positive number)."); return; } if (isNaN(rValueDesired) || rValueDesired <= 0) { alert("Please enter a valid Desired R-Value (must be a positive number)."); return; } if (isNaN(rValueCurrent) || rValueCurrent < 0) { alert("Please enter a valid Current R-Value (0 or greater)."); return; } if (isNaN(costPerBag) || costPerBag < 0) { alert("Please enter a valid Cost Per Bag (0 or greater)."); return; } if (isNaN(laborCostPerSqFt) || laborCostPerSqFt < 0) { alert("Please enter a valid Labor Cost Per Sq Ft (0 or greater)."); return; } // Define material properties var rValuePerInch; var sqFtPerBagAtR1; // Represents how many sq ft one bag covers to achieve R-1 var bagCoverageExampleRValue = 30; // Standard R-value used for manufacturer bag coverage data if (insulationType === "cellulose") { rValuePerInch = 3.7; // A typical 25lb bag of cellulose might cover 40 sq ft to R-30. // So, sqFtPerBagAtR1 = 40 sq ft * 30 R-value = 1200 sq ft-R sqFtPerBagAtR1 = 40 * bagCoverageExampleRValue; } else if (insulationType === "fiberglass") { rValuePerInch = 2.8; // Average for loose-fill fiberglass // A typical 25lb bag of fiberglass might cover 50 sq ft to R-30. // So, sqFtPerBagAtR1 = 50 sq ft * 30 R-value = 1500 sq ft-R sqFtPerBagAtR1 = 50 * bagCoverageExampleRValue; } else { alert("Invalid insulation type selected."); return; } // Calculations var totalArea = roomLength * roomWidth; var rValueNeeded = Math.max(0, rValueDesired – rValueCurrent); // Ensure R-value needed is not negative // Handle cases where no additional insulation is needed if (rValueNeeded <= 0) { document.getElementById("resultArea").innerText = "Total Area: " + totalArea.toFixed(2) + " sq ft"; document.getElementById("resultRValueNeeded").innerText = "Additional R-Value Needed: 0"; document.getElementById("resultThickness").innerText = "Required Thickness: 0 inches (Current R-value meets or exceeds desired)"; document.getElementById("resultBags").innerText = "Estimated Bags Needed: 0 bags"; document.getElementById("resultMaterialCost").innerText = "Estimated Material Cost: $0.00"; var calculatedLaborCost = totalArea * laborCostPerSqFt; document.getElementById("resultLaborCost").innerText = "Estimated Labor Cost: $" + calculatedLaborCost.toFixed(2); document.getElementById("resultTotalCost").innerText = "Total Estimated Cost: $" + calculatedLaborCost.toFixed(2); return; } var thicknessNeeded = rValueNeeded / rValuePerInch; var bagsNeeded = (totalArea * rValueNeeded) / sqFtPerBagAtR1; bagsNeeded = Math.ceil(bagsNeeded); // Always round up for bags var materialCost = bagsNeeded * costPerBag; var laborCost = totalArea * laborCostPerSqFt; var totalCost = materialCost + laborCost; // Display results document.getElementById("resultArea").innerText = "Total Area: " + totalArea.toFixed(2) + " sq ft"; document.getElementById("resultRValueNeeded").innerText = "Additional R-Value Needed: " + rValueNeeded.toFixed(0); document.getElementById("resultThickness").innerText = "Required Thickness: " + thicknessNeeded.toFixed(2) + " inches"; document.getElementById("resultBags").innerText = "Estimated Bags Needed: " + bagsNeeded + " bags"; document.getElementById("resultMaterialCost").innerText = "Estimated Material Cost: $" + materialCost.toFixed(2); document.getElementById("resultLaborCost").innerText = "Estimated Labor Cost: $" + laborCost.toFixed(2); document.getElementById("resultTotalCost").innerText = "Total Estimated Cost: $" + totalCost.toFixed(2); }

Understanding Blown-In Insulation

Blown-in insulation, also known as loose-fill insulation, is a popular choice for improving a home's energy efficiency. It consists of small, loose particles of insulation material that are blown into attics, wall cavities, and other hard-to-reach areas using specialized equipment. This method creates a seamless thermal barrier, reducing air leakage and heat transfer more effectively than traditional batt insulation in many applications.

Benefits of Blown-In Insulation:

  • Superior Coverage: It conforms to irregular spaces, filling gaps and voids around wiring, pipes, and framing, which are common sources of air leaks.
  • Enhanced Energy Efficiency: By creating a dense, uniform layer, it significantly reduces heat loss in winter and heat gain in summer, leading to lower energy bills.
  • Sound Dampening: The dense material also helps to absorb sound, making your home quieter by reducing noise transmission from outside or between rooms.
  • Eco-Friendly Options: Many blown-in cellulose products are made from recycled paper, offering an environmentally conscious choice.
  • Pest Deterrent: Some types, particularly cellulose, are treated with borate, which can act as a fire retardant and a deterrent to pests like insects and rodents.

Types of Blown-In Insulation:

The two most common types of blown-in insulation are:

  • Cellulose: Made primarily from recycled paper products, treated with fire-retardant chemicals. It has a high R-value per inch (around R-3.7) and is excellent for dense packing.
  • Fiberglass: Composed of fine glass fibers. It's naturally non-combustible and moisture-resistant. Its R-value per inch typically ranges from R-2.5 to R-3.0.

Understanding R-Value

R-value is a measure of thermal resistance, indicating how well an insulating material resists the conductive flow of heat. A higher R-value means greater insulating power. The recommended R-value for your home depends on your climate zone and the specific area being insulated (e.g., attic, walls, floor). For attics, common recommendations range from R-38 to R-60.

How to Use the Calculator:

  1. Area Length & Width: Measure the length and width of the area you plan to insulate (e.g., your attic floor).
  2. Desired R-Value: Determine the recommended R-value for your climate zone. You can find this information from the Department of Energy or local building codes.
  3. Current R-Value: If you're adding insulation to an existing layer, estimate its current R-value. If starting from scratch, enter 0.
  4. Insulation Material Type: Choose between Cellulose or Fiberglass. The calculator uses typical R-values per inch for each.
  5. Cost Per Bag: Enter the average cost of a bag of your chosen insulation material from your local supplier.
  6. Labor Cost Per Sq Ft: If you plan to hire a professional, enter their estimated labor cost per square foot. If you're doing it yourself, enter 0.
  7. Calculate: Click the button to get estimates for required thickness, number of bags, and total cost.

Factors Affecting Cost:

  • Material Type: Cellulose and fiberglass have different price points and R-values per inch, affecting the number of bags needed.
  • Desired R-Value: Higher R-values require more material and thus increase costs.
  • Area Size: Larger areas naturally require more insulation.
  • Accessibility: Difficult-to-access attics or wall cavities can increase labor costs.
  • DIY vs. Professional: Doing it yourself can save on labor but requires renting equipment.

DIY vs. Professional Installation:

Installing blown-in insulation can be a DIY project, especially for attics. You can rent insulation blowing machines from home improvement stores, often for free with a minimum insulation purchase. However, professional installers have specialized equipment, experience, and can often achieve a more uniform and dense application, particularly in tricky areas like wall cavities. Consider the complexity of your project and your comfort level with DIY tasks when making this decision.

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