Measuring for a Hardwood Deck: What You Need to Know

You’ve done your research; you’ve weighed your options and you’re ready to pull the trigger on your new hardwood deck. Now what? The next question is how much do you need? Calculating square footage for a deck is easy. Here are a few tips to help you through.

Step One - Don’t Run Out of Decking

The most common mistake made by homeowners and inexperienced carpenters is underestimating both total quantity and the length of the deck boards needed. If you run out of decking, your project stops. Dead in the water. Don't sell yourself short. Order enough material to get the job done, right, the first time.

It’s important to understand that not every deck board is perfect. In fact, a more truthful statement is NO decking board is perfect. It’s wood. It’s natural. There will be variations in each deck board. Plan for it.

A basic rule of thumb is to plan on using an extra 10% material. This will allow for ‘defect cutting’, waste, and trimming board lengths to hit on a deck joist. Also, most lumber has some checking at the end (small cracks) and most boards are not cut square. This is normal, not a defect. Plan on having to cut a couple inches off each hardwood decking board.

If your deck measures fourteen feet across, a fourteen-foot board probably will not work. You should go up to the next size. Better yet, you can minimize waste by using random length deck boards and putting joints in the field. Not only does using random length decking work better, it looks better, too. It gives you the freedom to use any deck board wherever it works best for your decking layout.

Likewise, if you figure that your deck is 300 square feet, you need more than 300 square feet of material. There is always waste. As previously stated, NO board is perfect. Plan for it. Sometimes a deck board has those small defects at the end, but sometimes it may have a defect or imperfection in the middle. Or perhaps your deck board is too bowed to work with, and you’ll have to cut it down into more usable lengths.

Trimming, defect cutting and making best use of your deck boards is normal, just part of working with wood. And don’t forget, (though it has never happened to me as far as you know…wink, wink), sometimes people make mistakes. If you cut one deck board wrong but only ordered exactly enough material, you’re out of luck.

Length x Width = Square footage of decking needed.

It’s basic math but converting that into a decking order is a bit more complicated. Square footage is calculated by multiplying length by width. Simple enough, but decking is sold by the linear foot not by the square foot. To convert it you need to know how many square feet is in a linear foot of decking.

In most cases deck lumber is either a nominal 4" (3-1/2" actual width) or a nominal 6" width (5-1/2" actual width) dimensions. Multiply the actual width of the board by 12 inches and divide by 144 (one square foot).

Professional Tips for Planning a Hassle Free Decking Installation

Here’s a professional cheat sheet to plan on the proper amount of decking materials, used by professional contractors and carpenters. Pro's make sure there is enough decking materials to get the job done right. Don't run short. Don't use unusable deck boards. Use the best decking boards, even if you have to trim them up to work best.

How to find the square footage of a board:

For 1 x 6: (5.5 x 12) / 144 = .46

For 1 x 4: (3.5 x 12) / 144 = .29

How to calculate how many linear feet of decking boards you will need based on the square footage of your deck:

To plan on the proper amount of lineal footage of 1 x 6 nominal decking:

Take your deck square footage and divide by .46. That's how many linear feet of 1x6 (or 5/4x6) decking you would need in a perfect world. Now add 10% for trimming, waste and best use of each deck board. Done.

For example:

• A 12 foot by 16 foot deck equals 192 square feet.
• 192 divided by .46 equals 418 linear feet of decking
• Multiply times 1.1 to add 10% for waste and trimming.
• Order 460 linear feet of 1x6 or 5/4x6 nominal decking.

To plan on the proper amount of lineal footage of 1 x 4 nominal deck boards:

Take your deck square footage and divide by .29. That's how many linear feet of 1x4 (or 5/4x4) nominal decking you would need in a perfect world. Now add 10% for trimming. Done.

For example:

• A 12 foot by 16 foot deck equals 192 square feet.
• 192 divided by .29 equals 662 linear feet of 1x4 nominal decking
• Multiply times 1.1 to add 10% for waste and trimming.
• Order 729 linear feet of 1x4 or 5/4x4 nominal decking.

Planning for the right amount of deck fasteners

Excellent. You know have the right amount of decking to order. It's time to get the right amount of decking fasteners for your deck project. Hidden deck fasteners are beautiful, and can be used in many different types of decks. Decking screws are stronger and can be used on all decks.

Learn more: 6 Things You Should Know About Hidden Deck Fasteners

How to find the number of hidden deck fasteners you need for 16” O. C. framing:

Formula: Multiply .75 x linear foot = number of hidden deck fasteners

Example:

• Take .75 and multiply by 729 linear feet = 547 hidden fasteners
• Now add 10%.
• Order 602 hidden deck fasteners.