.svg)
Deck planning tool
Composite deck board estimator
The short version of the take-off. Enter a deck size, or a total area if you already have one, and this returns the square metres, the linear metres of board and the number of 2,500 mm Tarimatec boards to order, with a waste allowance included. Same arithmetic as the full calculator, four fields instead of eight.
The arithmetic, in one line
Deck area divided by the board's coverage pitch gives linear metres of board. Multiply by the waste allowance, divide by the 2.5 m board length, round up. That is the whole calculation, and it is worth understanding rather than trusting, because the coverage pitch is where people go wrong.
Boards per square metre, said three ways
Tarimatec's literature quotes coverage as about 6.5 boards per square metre, and that figure confuses almost everyone who meets it, because a 2,500 mm board is obviously much bigger than a sixth of a square metre. The number is really a linear-metre figure. Here is the same fact expressed three ways.
| Expressed as | Hollow, 150 mm board | Solid, 149.2 mm board |
|---|---|---|
| Coverage pitch, board plus 5 mm side gap | 155.0 mm | 154.2 mm |
| Linear metres of board per square metre | 6.45 m | 6.48 m |
| Full 2,500 mm boards per square metre | 2.58 | 2.59 |
| Square metres covered by one board | 0.3875 m² | 0.3855 m² |
| Boards for a 24 m² deck, before waste | 62 | 63 |
The 5 mm side gap is not optional and it is not a taste decision. It is set physically by the hidden H clip that holds each board down, so every board in the field sits at that pitch whether you plan for it or not. Leave it out of the arithmetic and you will be roughly 3 per cent short across the deck.
How much waste to allow
- 5 per cent for a straight rectangle with boards running the long way and no cut-outs. This is the sensible default.
- 8 per cent once you have a picture frame border, mitred corners, angled edges, or a post or planter to cut around. Every cut end is a piece you cannot use elsewhere.
- 10 per cent or more for diagonal and herringbone layouts, small awkward decks, and any deck where the run length divides badly into 2.5 m. A 2.6 m run wastes 1.9 m per board, and no waste percentage fixes that; changing the board direction sometimes does.
One thing worth checking before you settle on a number: how your run length divides into 2,500 mm. Deck runs of 2.5 m, 5.0 m and 7.5 m are almost free of end waste. Runs just over a multiple are the expensive ones.
What a board count does not tell you
Boards are usually less than half the material on a Tarimatec deck. The aluminium joist at 350 mm centres, the closed perimeter frame, 25 hidden clips per square metre, the substrate anchors at 500 mm and the fascia are all still to come, and the substructure is where most of the cost and nearly all of the labour lives. If you are budgeting rather than just curious, run the full board, joist and clip calculator instead.
Also settle the end gaps before anything is cut. Composite boards move with temperature, and the gap you leave depends on the board length and how warm it is on the day of install. That is what the expansion gap guide is for.
Related: all planning tools, the installation guide, and the cost calculator once quantities are settled.
Check the colour before you order the count
A board count is easy to change; a whole deck in a colour you have only seen on a screen is not. Paid sample tiles ship from Vaughan, Ontario in 5 to 10 business days. Boards themselves are import to order, so allow 8 to 12 weeks from a confirmed order.
Order samples