How much waste should I order for decking?

For a simple rectangular deck, add 10% waste. For decks with angles, curves, or diagonal patterns, add 15–20%. This accounts for cuts, fitting, and any defective boards.

How many deck boards do I need for a 12×12 deck?

A 12×12 deck is 144 square feet. With 10% waste, you need about 159 sq ft of material. Using ipe bundles (15 sq ft each), that is 11 bundles. Using composite slats (21 sq ft each), that is 8 bundles.

Should I order extra decking material?

Yes. Always order at least 10% extra for waste from cuts and installation. Consider ordering 1–2 additional bundles beyond waste for future repairs, as matching boards from different batches can vary slightly in color.

How do I calculate decking for an L-shaped deck?

Split the L-shape into two rectangles. Calculate the area of each rectangle, add them together, then add your waste factor. Example: A 10×20 section + an 8×12 section = 200 + 96 = 296 sq ft.

What size deck boards should I use?

The most common decking board width is 1×6 (nominal). This provides a good balance of coverage per board, structural span capability, and visual proportion. Wider boards cover area faster but may be more prone to cupping.

How Much Decking Do I Need? Calculator & Estimation Guide

Ordering the right amount of decking material is critical for any project. Too little means delays and mismatched boards from different batches. Too much wastes money. This guide walks you through the calculation process and helps you account for waste, cuts, and complex deck shapes.

Step 1: Measure Your Deck Area

Start by measuring the total area of your deck in square feet. For rectangular decks, multiply length × width.

Example: A deck that is 20 feet long and 12 feet wide = 240 square feet.

For irregular shapes, break the area into rectangles and triangles, calculate each separately, and add them together.

Rectangle: Length × Width
Triangle: (Base × Height) ÷ 2
L-shaped deck: Split into two rectangles

Step 2: Add Waste Factor

Every decking project generates waste from cuts, defects, and fitting around obstacles. Industry standard waste factors:

Simple rectangular deck: Add 10% waste
Deck with angles or curves: Add 15% waste
Complex multi-level deck: Add 15–20% waste
Diagonal board pattern: Add 15–20% waste

Example: 240 sq ft deck + 10% waste = 264 sq ft of material needed.

Step 3: Convert to Bundles or Board Feet

Different products are sold in different units. Here is how common iLumber products are packaged:

Product	Coverage per Bundle
Ipe Wood Decking (1×6)	15 sq ft per bundle
Thermo Wood Ayous Cladding	15 sq ft per bundle
Natural Elegance Composite Slats	21 sq ft per bundle

Example: 264 sq ft ÷ 15 sq ft/bundle = 17.6 → round up to 18 bundles.

Always round up to the nearest whole bundle. You cannot order partial bundles.

Planning a decking or cladding project?

Use our material estimator or explore our premium hardwood and thermo wood materials.

Shop Ipe Decking Shop Composite Slats Explore Thermo Ayous

Common Deck Sizes and Material Estimates

Deck Size	Sq Ft	+10% Waste	Ipe Bundles (15 sf)	Composite Bundles (21 sf)
10×10	100	110	8	6
12×12	144	159	11	8
14×20	280	308	21	15
16×24	384	423	29	21
20×30	600	660	44	32

Tips for Accurate Estimation

Measure twice, order once — verify all dimensions before placing your order
Account for stairs, borders, and picture-frame edges separately
If your deck wraps around a corner, measure each section independently
Order all material from the same batch to ensure color consistency
Consider ordering 1–2 extra bundles for future repairs

Using the iLumber Material Estimator

Every iLumber product page includes a built-in material estimator. Simply enter your square footage or use the bundle calculator, and the waste adjustment tool will help you add the right amount of extra material.

The waste adjustment buttons (+10%, +15%, +20%) automatically round up to the nearest whole bundle, so you always order the right amount.