Deck board calculator: rows, boards and fasteners
The width across the deck, divided by a board and its gap, is the rows. Rows times how far they run is the feet of board, and those feet, with your extra for cuts, divided by the length you buy, is the boards. In the example below a deck of 192 square feet takes 29 boards. This page counts boards. The frame under them, the footings, the rail and the permit come from the plans and your building department.
Count the deck boards
Type the size of the deck and the boards you are laying. You get the rows, the feet of board, the boards to buy and the fasteners, and lines to put on a quote. It counts the boards, and nothing under them.
The deck
A deck that is not a rectangle is counted a rectangle at a time.
The side the boards lie along, end to end.
The side the rows are counted along.
The boards
It starts at 5.5, what decking sold as 6 inches wide measures. A board sold as 4 inches wide measures 3.5.
It starts at 0.125, an eighth of an inch: the wood council's deck guide says approximately that.
Leave it empty to see the boards in feet.
It starts empty: we found no figure for a deck at a source worth naming. Type your own.
The fasteners
Leave the first of these empty to count boards only.
From the plans. This page does not say how far apart joists go.
It starts at 2, what the wood council's deck guide gives.
Type how far the boards run and how far the deck is across them. The count shows here.
The boards of one deck, counted
An example with made-up numbers, not a going rate
Say the boards of a deck run 16 feet and the deck is 12 feet across them: 192 square feet. Say the boards are 5.5 inches wide with an eighth of an inch between them: 26 rows, and 416 feet of board. Say you add 10% for cuts and buy boards 16 feet long: 457.6 feet, so 29 boards. Say your plans put the joists 16 inches apart: the boards cross 13 of them, and at 2 screws at each crossing that is 676 screws.
From the width to the boards
- Rows: the distance across the boards, in inches, plus one gap, divided by a board and a gap, rounded up. The one gap is added because the last row has none after it.
- A board is narrower than its name. In the Southern Forest Products Association's table of standard sizes, decking sold as 6 inches wide is 5 and a half inches once it is dressed, and a board sold as 4 is 3 and a half.
- Feet of board: the rows times how far the boards run.
- Boards: those feet, plus your extra for cuts, divided by the length of the boards you buy, rounded up.
- Fasteners: the joists a board crosses are the run divided by their spacing, rounded up, and one more for the far end. Rows times joists is the crossings, and the crossings times the fasteners at each is the count.
What the wood council says about decking
- The American Wood Council publishes a deck guide, DCA 6, based on the 2015 International Residential Code: American Wood Council, DCA 6: Prescriptive Residential Wood Deck Construction Guide. Two of its lines are about the boards themselves. They are given here as the council's words, not as advice from this page.
- On fastening, the guide says: "Attach decking to each joist with 2-8d threaded nails or 2-#8 screws." The box for the fasteners at each crossing starts at that 2.
- On spacing, it says: "Space decking boards approximately 1/8" apart." The box for the gap starts at an eighth of an inch, typed as 0.125.
- The guide says of itself: "Where differences exist between provisions of this document and the IRC, provisions of the IRC shall apply." And: "All construction and materials must be approved by the authority having jurisdiction." It is about wood. A composite board has its maker's own gap, fastening and joist spacing, and this page does not count composite.
Three boxes that start empty
The length of the boards, the extra for cuts and the spacing of the joists all start empty.
The length is whatever you buy. Boards as long as the deck runs make every row one piece. Shorter boards make every row more than one piece, end to end, and the counter says so when that happens.
The extra for cuts has no figure here because we found none for a deck at a source worth naming. Your last deck is the place to get it: feet bought against feet laid.
The joist spacing comes from the plans. This page does not say how far apart joists go, and the count of joists it shows is for the fasteners only.
What this count is not
- It is not a framing plan. No joist, beam, post or footing is sized here, and no span is checked. A deck holds people up: its frame comes from the plans, an engineer or your building department.
- It does not cover the rail, the steps, a border round the edge or the boards on the face of the frame.
- It is for wood. Composite decking is laid to its maker's own figures, and this page does not have them.
- It does not price anything. TailGateBid has no price data, and the box for what a board costs you is on the page that prices the deck.
From the count to the quote
The lines under the calculator start with the square feet of decking, then the boards as you buy them, then the fasteners. They are the decking and nothing else: the frame, the rail and the steps are lines you add from the plans.
Next, work out what to charge for the whole deck: the boards at what one costs you, everything else on the plans as one figure, your hours on the frame and on the decking, and a price for each square foot. Or put the lines on an estimate and print it.
Pouring footings to the sizes on the plans? The concrete calculator turns them into cubic yards and bags.
Where each number comes from
- The box for the width of a board starts at 5.5 inches. In the Southern Forest Products Association's table of standard sizes, decking sold as 6 inches wide is that width once it is dressed, and a board sold as 4 inches wide is 3.5. Starting at the wider is our choice. Southern Forest Products Association, Standard Sizing, . (our choice, change it)
- The box for the gap between boards starts at 0.125 of an inch, which is an eighth. The American Wood Council's deck guide says: "Space decking boards approximately 1/8" apart." Starting there is our choice. The guide is for wood decking: another kind of board has its maker's own figure. American Wood Council, DCA 6: Prescriptive Residential Wood Deck Construction Guide, . (our choice, change it)
- The box for the nails or screws where a board crosses a joist starts at 2. The American Wood Council's deck guide says: "Attach decking to each joist with 2-8d threaded nails or 2-#8 screws." Starting there is our choice. What the plans or the fastener's maker call for decides. American Wood Council, DCA 6: Prescriptive Residential Wood Deck Construction Guide, . (our choice, change it)
On a TailGateBid quote the decking can be a line by the square foot, with the frame, the rail and the steps as lines of their own.
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Sources
Related
- Deck buildingA wood deck's square feet, its boards counted at your cost, everything else off the plans, and the hours on the frame kept apart from the hours on the decking.
- Estimate makerType a few lines and print a clean estimate or quote, in English or Spanish. Nothing you type is sent anywhere.
- Concrete calculatorSlabs, footings and round forms into cubic yards to order and bags to buy, with lines to put on a quote.
- Job price16 hours of work and $600 of materials cost you $1,320. See what five prices would leave you.
By TailGateBid. .
A count is as good as the measurements you type. What is printed on the bag, the can, the pail or the box you buy decides, and so do the plans.