Having a deck gives you additional living space and creates an area for you to get outside and enjoy the nice weather. When it comes to building a deck, a variety of materials are needed to make it happen. With so many options for all the materials, it’s recommended that you consider your home’s design and your current outdoor space as you plan your new deck.
Guessing and calculating the number of materials you need to build a deck is an art and a science. It’s a good place to start with a detailed drawing of your deck, which you will need to have when applying for a permit and for help from your local hardware store. You can make this yourself or contact a professional contractor. The drawing should have specific sizes and the number of deck piers or footings you’ll need and the size and length of any posts and beams. Your drawing will also indicate ledger and deck frame size, joist spacing, decking type, railing post size and quantity along with any stairs that will indicate the width and approximate length.
Knowing and purchasing materials in advance will prevent construction delays and other material obstacles; it’s always better to be over-prepared! We have gathered the information to help you create a list of materials for your deck-building project!
Before your construction design can be created, measurements must be taken and placement of your house and arrangement of footings must be determined. When measuring out your deck and determining your footings you will need batter boards and mason’s string.
A standard deck will require 4 footings parallel to the house, and they will need to be temporarily braced by 6-inch-by-6-inch posts. Double boards will need to be used to build beams on the top row of the post to frame the edges of your deck. These beams will be topped with post caps. Joist hangers and blocking pieces are also needed to be placed between the joists.
Start From The Base
You must determine if your deck will require in-ground footings, be set on piers, or if it is small enough grade to be set only on deck blocks. Start with the concrete required for in-ground footings or grade blocks. If you are using brackets to set the posts on piers, including the size and quantity on your list. Remember to include the bolts or other fasteners and hardware needed for each footing.
When constructing your footings for your posts for the deck, you will require concrete to secure them in their holes. To determine the amount you will need, you have to do a little math (sorry!). First, measure the hole in inches, then divide the diameter in half and multiply it by itself. Then, multiply that number by 3.14. The result of that will then be multiplied by the depth of the hole in inches. Finally, divide your answer by 1,278 (one cubic foot). Your final number is the amount of cubic concrete needed to fill that hole.
You will need to use a 60-pound bag of concrete for half a cubic foot. Once you know the amount of concrete needed, divide it by 0.5 to calculate the number of bags you will need. Or, with the total amount of cubic feet you’ve calculated, you can ask a concrete supplier to deliver that much ready-made concrete.
Double-Check Sizes For Safety
You will need to consult a span table to make sure your joists are heavy enough to carry the load. These charts show you how large your joists need to be for the size of the deck you are building. Usually, the external frame, or rim joists, are the same size or slightly larger than the internal joists. Make sure to include enough lumber for the outside frame.
You will also need joist hanger brackets and fasteners for each piece along with brackets, screws or nails and bolts for attaching to posts. When shopping for hardware, the most detail you can provide about your deck’s construction plan will make shopping for the necessary hardware be less stressful.
For the standard, elevated deck, there are many board and decking materials available. To calculate the amount of treated wood or other deck boards you will need, multiply the length of your proposed deck surface times the width to get the decking square footage. Account for any overhangs and provide yourself will an allowance for some waste when it comes to your deck floor materials. For example, for a 12 x 16 deck, if you choose to use 20-foot boards, you will need to purchase 22 of these boards. Similarly, 18-foot boards will call for 24 boards, 16-foot boards will call for 27 boards, 14-foot boards will call for 31 boards, and so on with your options factoring in about 5% waste.
The board size and amount can depend on the material you choose to work with. There are many options out there that provide different looks and costs. You can build with pressure-treated cedar, redwood, ipe or even wood composites. Composite materials, such as PVC, are also an option. Composite is more expensive but it requires less regular maintenance and refinishing, unlike wood, saving you money over time.
Always Have Extras
You should plan to include about 15% more deck material than needed for missed cuts or unusable small pieces. When calculating decking material, remember to include stairs and benchtops if they are to be made of the same material.
Lumber materials sizes are “nominal” meaning that a 2×6 deck board is only 5.5 inches wide. You can account for these lengths in the 15% extra materials. Another thing to look out for is the 5/4 deck board. This is a standard decking material size, that is about 1 and 1/8 inches thick, as opposed to the 1 and 1/2 inch thick 2x lumber used for framing.
Railings & Stairs
The materials for the accessories, like rails, steps and skirting will depend on your deck design. Skirting is optional unless building codes call for it. Necessary extra deck material or lumber includes railings and stairs. These will call for additional wood or other material. Refer to your drawing to estimate the amount of posts, balusters, rails and railing material, stair treads and stringers. Before constructing your railing or stairs, make sure your estimate is correct by measuring on-site, which may differ from earlier numbers. Purchasing additional wood will help you avoid issues.
If your deck is below a certain local code dictated height, usually 18 or 24 inches, or if you plan on having your stairs run the width of the one side of your deck, you will not need to install a railing.
Your deck will be secured with hardware. Calculate how many metal connectors, fasteners, bolts, and other hardware for framing you will need. To estimate a good amount of screws or nails, plan to use 5 pounds of screws for 100 square feet of decking you are planning to build.
When buying hardware, know that getting cheap or lower-quality screws will result in them corroding, shortening the lifespan of your deck. Stainless steel or coated screws made for pressure-treated wood are made to resist corrosion and extend the life of a deck.