How many decking boards do I need?
Each row of decking takes 145 mm of the deck: a 140 mm board and the 5 mm gap the hidden clips leave between boards. Divide the depth of the deck by 145 mm to get the rows, then work out how many 5.4 m boards each row is cut from.
The calculator does that for every row of the deck you draw, counts whole boards with the offcuts included, and puts breaker boards where a run is longer than one board. The table below is worked out the same way for common rectangular decks.
A picture frame does not always add boards. On a 6 m deck with no frame, the boards are laid in three equal bays about 1.9 m long, and a 5.4 m board only cuts two of those. The frame takes the outside course off the field, so the bays come down to about 1.8 m and each board cuts three: less waste, fewer boards.
| Deck | Area m² | Boards, no frame | Boards, picture frame | Fixing boxes |
|---|---|---|---|---|
| 3 × 3 m | 9.0 | 21 | 23 | 1 |
| 4 × 3 m | 12.0 | 21 | 23 | 2 |
| 4 × 4 m | 16.0 | 28 | 30 | 2 |
| 5 × 4 m | 20.0 | 28 | 30 | 2 |
| 6 × 4 m | 24.0 | 44 | 33 | 3 |
| 6 × 5 m | 30.0 | 55 | 40 | 3 |
| 8 × 4 m | 32.0 | 44 | 46 | 4 |
Picture frame decking
Picture frame decking runs one, two or three courses of boards around the edge of the deck, so no board ends show at the edge. The corners are mitred, or square where one side runs through and the other butts into it.
A deck with a sloping side, such as a triangle, can only have a mitred frame, and the calculator sets that for you.
Breaker boards
A breaker board runs across the deck where the boards would otherwise be longer than one 5.4 m board, so you never butt two boards end to end in the middle of the deck. The calculator spaces the breakers evenly: a 10 m deck gets one breaker down the middle.
When a deck is longer than one board in both directions, the breakers and the frame sides that run with them are joined end to end with a 5 mm gap over a noggin, as the MexyTech installation guide shows.
Joists, fixing boxes and fascia
MexyTech boards need joists at 400 mm centres on a home deck and 300 mm centres for commercial or high-traffic decks. One decking box has the clips, starter clips and screws for 10 m² of deck at 400 mm centres; closer joists need more.
The fascia is a 140 × 11 mm board in the same colours, one, two or three boards high depending on how high the deck sits. Deck sizes in the calculator are to the edge of the deck boards; the fascia is not added to them.
Questions
Yes. Draw your deck, change it as often as you like, and add the list to a quote when you are ready. There is nothing to sign up for.
Yes. Pick a shape and drag the corners or tap a length to type it, or draw your own shape corner by corner. You can also add a second area, such as a step or a landing.
Yes. It counts whole 5.4 m boards with the offcuts included, and shows the offcut each board leaves in every bay.
Yes. Every line has − and + buttons and you can type a number. The suggested figure stays on show so you can go back to it.
Copy the link or email it to yourself. Opening the link brings the plan back exactly as you left it, ready to change or add to a quote.
Not yet. It plans MexyTech composite decking today. Timber decks are laid and fixed differently, so they need their own rules before they can be added.
Disclaimer
A guide only. Check the MexyTech installation guide and your builder before you order, and talk to us about anything unusual.