*Estimates are based on national averages. Actual local contractor bids may vary by ±15%.
function calculateRoofCost() {
// Get Inputs
var footprint = document.getElementById('homeFootprint').value;
var pitchMultiplier = document.getElementById('roofPitch').value;
var materialCostPerSqFt = document.getElementById('roofMaterial').value; // This is actually price per square / 100 roughly, logic below
var hasTearOff = document.getElementById('tearOffCheck').checked;
var hasPermits = document.getElementById('permitCheck').checked;
// Validate Input
if (footprint === "" || footprint <= 0) {
alert("Please enter a valid square footage for the home footprint.");
return;
}
// Convert strings to floats
var baseArea = parseFloat(footprint);
var pitchFactor = parseFloat(pitchMultiplier);
var materialPricePerSquare = parseFloat(materialCostPerSqFt); // The value in select is Price Per Square (100sqft)
// 1. Calculate Roof Area
// Area = Base * Pitch Factor
// We add 10% waste factor standard for cuts/overlaps
var wasteFactor = 1.10;
var actualRoofArea = baseArea * pitchFactor * wasteFactor;
// Calculate "Squares" (1 square = 100 sq ft)
var roofSquares = actualRoofArea / 100;
// 2. Calculate Costs
// Material & Install Cost
var totalMaterialCost = roofSquares * materialPricePerSquare;
// Tear off Cost (Average $70 per square)
var tearOffCost = 0;
if (hasTearOff) {
tearOffCost = roofSquares * 70;
}
// Permits
var permitCost = 0;
if (hasPermits) {
permitCost = 400; // Flat rate estimate
}
// Total
var totalCost = totalMaterialCost + tearOffCost + permitCost;
// 3. Format & Display Results
// Helper for currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 0,
maximumFractionDigits: 0,
});
document.getElementById('res-area').innerText = Math.round(actualRoofArea).toLocaleString() + " sq ft (" + Math.round(roofSquares) + " Squares)";
document.getElementById('res-material').innerText = formatter.format(totalMaterialCost);
document.getElementById('res-tearoff').innerText = formatter.format(tearOffCost);
document.getElementById('res-permits').innerText = formatter.format(permitCost);
document.getElementById('res-total').innerText = formatter.format(totalCost);
// Show results div
document.getElementById('roofing-result').style.display = 'block';
}
How to Estimate Roofing Costs in 2024
Replacing a roof is one of the most significant investments a homeowner will make. Whether you are dealing with storm damage, aging shingles, or simply looking to upgrade your home's curb appeal, understanding the financial breakdown is crucial. This guide walks you through the factors that influence your final quote and how to budget effectively for your roofing project.
1. Understanding the "Square"
In the roofing industry, you won't often hear contractors talk about square footage in the same way realtors do. Instead, roofers use a unit of measurement called a "Square".
Key Metric: One "Square" equals 100 square feet of roof area. If your roof is 2,000 square feet, a roofer will say it is a 20-square job.
Our calculator above automatically converts your home's footprint into estimated roof squares, accounting for the slope and necessary waste materials.
2. Primary Cost Factors
While the size of your home is the starting point, three main variables will dictate the final price tag:
A. Material Selection
The material you choose has the largest impact on price. Here is a breakdown of common options:
Asphalt Shingles (3-Tab): The most affordable option. Good for budget repairs but has a shorter lifespan (15-20 years). Expect to pay between $350-$400 per square installed.
Architectural Shingles: The standard for modern homes. They add dimension and durability (25-30 years). Costs range from $450-$600 per square.
Metal Roofing: Extremely durable and energy-efficient. Standing seam metal roofs can last 50+ years but cost significantly more, often $900-$1,200 per square.
Tile & Slate: The premium tier. Heavy, long-lasting, and distinct. These require specialized installation and can cost upwards of $1,500 per square.
B. Roof Pitch (Steepness)
A "walkable" roof is cheaper to replace than a steep one. As the pitch increases, safety equipment (harnesses, scaffolding) becomes necessary, and the work proceeds slower. A steep roof not only has more surface area than a flat roof covering the same footprint, but the labor cost per square also rises due to the difficulty and risk involved.
C. Tear-Off and Disposal
Can you layer new shingles over old ones? In some jurisdictions, yes, but it is rarely recommended. "Tear-off" refers to removing the existing material down to the deck. This allows the roofer to inspect the plywood underneath for rot. Tear-off is labor-intensive and requires dumpster rental fees, typically adding $60-$90 per square to the total.
3. Hidden Costs to Watch For
When reviewing a contractor's estimate, ensure these items are discussed so you aren't surprised by change orders later:
Decking Repair: Once the old shingles are off, if the wood underneath is rotten, it must be replaced. This is usually billed per sheet of plywood ($60-$100/sheet).
Ventilation: Proper attic airflow extends the life of your roof. Adding ridge vents or soffit vents may be an extra line item.
Flashing: The metal strips around chimneys, valleys, and skylights prevent leaks. Reusing old flashing is risky; always budget for new flashing.
Permits: Most municipalities require a building permit for re-roofing.
Conclusion
While online calculators provide a solid baseline, every roof is unique. We recommend getting at least three written quotes from licensed, insured local contractors. Use the estimate generated above to ensure the quotes you receive are within a reasonable market range. Remember, the cheapest quote is not always the best—quality installation is just as important as the material itself.