Building a new deck is an exciting home improvement project. Choosing composite decking offers a durable, low-maintenance alternative to traditional wood. However, understanding the cost factors involved is crucial for proper budgeting. This calculator helps you estimate the total cost based on various project parameters.
Key Cost Components
Composite Decking Material: This is typically the largest single cost. The price varies significantly by brand, style (e.g., capped vs. uncapped, grain pattern), and color. The calculator estimates the amount of decking needed based on your deck dimensions and board width, then multiplies it by the cost per linear foot.
Railing: A deck often requires railing for safety and aesthetics. The cost depends on the material, style, and linear footage of railing needed.
Stairs: If your deck includes steps, each step adds to the material and labor cost.
Foundation/Posts: The support structure, typically posts and concrete footings, is essential. The cost is estimated based on the number of posts required, influenced by deck height and dimensions.
Labor: Professional installation significantly impacts the total cost. This includes the time taken for framing, decking, railing installation, and finishing. The estimated labor hours and hourly rate are key here.
Fasteners & Accessories: While not explicitly an input, costs for screws, hidden fasteners, underlayment, and waste factor should be considered in the overall budget. Our calculator simplifies this by focusing on major components.
How the Calculator Works
Our Composite Deck Cost Calculator uses the following logic:
Board Coverage: Calculates how many linear feet of composite board are needed. This considers the width of the composite boards and assumes a standard installation with minimal waste.
Total Decking Cost:Total Linear Feet of Decking * Board Cost per Linear Foot.
Railing Cost: Assumes railing goes around the perimeter of the deck. Calculated as (2 * Deck Width + 2 * Deck Length) * Railing Cost per Linear Foot. (Note: This is a simplified perimeter; actual railing needs may vary based on stairs, gates, and openings).
Stair Cost:Number of Stair Steps * Cost per Stair Step.
Foundation Cost: Estimates the number of posts needed based on typical spacing requirements for a given deck height and size, then multiplies by Foundation Cost per Post. A common estimate is one post per ~8-10 linear feet of perimeter for a moderately high deck.
Labor Cost: Calculated as Estimated Labor Hours * Labor Cost per Hour.
Total Estimated Cost: The sum of all individual cost components (Decking, Railing, Stairs, Foundation, Labor).
Important Note: This calculator provides an *estimate*. Actual costs can vary due to material waste, complex designs, local labor rates, permits, and specific site conditions. Always obtain detailed quotes from contractors for precise pricing.
function calculateDeckCost() {
var deckWidth = parseFloat(document.getElementById("deckWidth").value);
var deckLength = parseFloat(document.getElementById("deckLength").value);
var deckHeight = parseFloat(document.getElementById("deckHeight").value);
var joistSpacing = parseFloat(document.getElementById("joistSpacing").value);
var boardWidth = parseFloat(document.getElementById("boardWidth").value);
var boardCostPerLinearFt = parseFloat(document.getElementById("boardCostPerLinearFt").value);
var railingCostPerLinearFt = parseFloat(document.getElementById("railingCostPerLinearFt").value);
var stairCostPerStep = parseFloat(document.getElementById("stairCostPerStep").value);
var foundationCostPerPost = parseFloat(document.getElementById("foundationCostPerPost").value);
var laborCostPerHour = parseFloat(document.getElementById("laborCostPerHour").value);
var laborHours = parseFloat(document.getElementById("laborHours").value);
var totalCost = 0;
var deckingCost = 0;
var railingCost = 0;
var stairCost = 0;
var foundationCost = 0;
var laborCost = 0;
var deckAreaSqFt = 0;
var linearFtOfDecking = 0;
var perimeter = 0;
var numberOfPosts = 0;
// — Input Validation —
if (isNaN(deckWidth) || deckWidth <= 0 ||
isNaN(deckLength) || deckLength <= 0 ||
isNaN(deckHeight) || deckHeight < 0 ||
isNaN(joistSpacing) || joistSpacing <= 0 ||
isNaN(boardWidth) || boardWidth <= 0 ||
isNaN(boardCostPerLinearFt) || boardCostPerLinearFt < 0 ||
isNaN(railingCostPerLinearFt) || railingCostPerLinearFt < 0 ||
isNaN(stairCostPerStep) || stairCostPerStep < 0 ||
isNaN(foundationCostPerPost) || foundationCostPerPost < 0 ||
isNaN(laborCostPerHour) || laborCostPerHour < 0 ||
isNaN(laborHours) || laborHours 1, there's at least one stair calculation.
var estimatedSteps = Math.ceil(deckHeight * 7 / 12); // Rough estimate: 7 inches rise per step, convert height to inches
stairCost = estimatedSteps * stairCostPerStep;
// 4. Foundation Cost
// Estimate number of posts. A rough rule of thumb: 1 post per 8-10 linear feet of perimeter for a standard height deck.
// For higher decks, more posts might be needed. This is a simplification.
var postsPerLinearFt = 0.12; // Roughly 1 post per 8 ft of perimeter
if (deckHeight > 5) postsPerLinearFt = 0.15; // Slightly more for higher decks
numberOfPosts = Math.ceil(perimeter * postsPerLinearFt);
// Ensure at least 4 posts for smaller decks, or if perimeter is very small
if (numberOfPosts 0) {
numberOfPosts = 4;
}
foundationCost = numberOfPosts * foundationCostPerPost;
// 5. Labor Cost
laborCost = laborHours * laborCostPerHour;
// 6. Total Cost
totalCost = deckingCost + railingCost + stairCost + foundationCost + laborCost;
// — Display Result —
var resultHtml = "