Deck worked example: 5.0 m x 3.6 m backyard deck

BuildTrue deck pack. Estimates only. This example uses the same formulas as the deck calculator on the pack page and the standalone BuildTrue deck estimator. Verified by hand, step by step, below.

Inputs

Input	Value
Deck length (boards run along this direction)	5.0 m
Deck width	3.6 m
Board width	140 mm (0.140 m)
Gap between boards	6 mm (0.006 m)
Joist spacing	400 mm (0.4 m) on centre
Screws per board per joist crossing	2

Step by step arithmetic

1. Board pitch (the width each board actually covers):

140 mm + 6 mm = 146 mm = 0.146 m.

1. Boards across the width:

3.6 m / 0.146 m = 24.6575. Round up with the epsilon safe ceiling: 25 boards. Check: you cannot buy 0.66 of a board row, so 24 boards would leave the last strip uncovered.

1. Linear length of decking:

25 boards x 5.0 m per board = 125 linear metres. In imperial: 125 / 0.3048 = 410.1 linear feet.

1. Joists:

5.0 m / 0.4 m = 12.5, ceiling = 13 spaces worth of count, plus 1 end joist = 14 joists. Each joist runs the width of the deck: 3.6 m per joist.

1. Screws:

25 boards x 14 joist crossings x 2 screws = 700 screws.

Purchasable counts

Item	Raw result	Buy
Deck boards, 5.0 m stock length or the nearest stock length at or above 5.0 m	25 boards exactly from the count	25 boards, plus 1 spare board recommended for a bad crown or a miscut (26 total if you take the spare)
Joists, 3.6 m stock length or nearest above	14 joists	14 pieces
Deck screws	700 screws	Boxes totalling at least 700 screws. A 1,000 count box covers the job with spares; two 500 count boxes do the same
Joist hangers	1 per joist end landing on a beam or ledger	Count on the frame layout; not produced by the board calculator

Sample material list for this job

Item	Specification	Quantity
Deck boards	140 mm wide, 5.0 m length	25, plus 1 spare recommended
Joists	Length 3.6 m	14
Rim and ledger boards	To match frame layout	As laid out on site
Deck screws, exterior rated	Length suited to board thickness	At least 700 count
Ledger flashing and structural ledger fasteners	As designed	1 set for the ledger run
Footing material	As designed for this deck	Per footing design, not counted here

Notes and limits

• The calculator counts boards, linear length, joist crossings, and screws. It does not design footings, beams, stairs, or railings, and it does not check structure or code.
• If the deck width reading on site is wider than 3.6 m at any point, rerun the count with the widest reading. The board count is set by the widest row.
• Estimates only. Confirm local code and permit requirements with your municipality and a qualified professional before you build.