Build a Deck

A deck is the rare project where the materials list and the safety case are the same document. Joist span, beam size, post count and footing volume aren't just an order — they're what keeps the structure standing with twenty people on it at a summer party. That's why the takeoff starts from span tables rather than guesswork, and why the first step in this hub is a design check rather than a materials run.

The sequence follows the build: design and span check first, because a design you can't frame is a drawing, not a plan. Then footings and concrete, posts and beam, joists, deck boards and finishing. The deck lumber calculator totals the framing order — joists, beam, posts, boards and fasteners — from your dimensions and span tables, and the concrete calculator sizes the footing pours that carry all of it.

One honest gap is flagged in the plan below: railings and guards are not in the lumber takeoff. Requirements change with deck height and country, so confirm the local rule first, then count the parts for the system you've chosen. Timber sizes themselves vary by region too — the same wall is framed from very different boards in metric and imperial countries — which is why the timber guide is on the reading list.

1. Design it and check the spans. Fix the size, the height off grade and the board direction, then check joist spans against timber size and spacing. A typical spacing is 400 mm (16 in) centres; the span tables in the deck guide set what that timber can carry.
2. Pour the footings. Count posts, then size the holes — a typical round footing is around 300 mm (12 in) across, dug to below the local frost line, which varies enormously by climate. Hole volume times post count is the concrete order.
3. Stand the posts and beam. Post length runs from footing to beam; beam size follows the span between posts. Adjusting post spacing at this stage is a design change — re-run the span check, not just the count.
4. Frame the joists. Count them from deck length and spacing, add rim joists and blocking over the beam. This is the bulk of the lumber order and the part the calculator itemises.
5. Lay the boards. Decking area plus waste — typically 5–10% for straight laying, more for diagonals. Fastener counts come with the takeoff.
6. Plan railings and stairs — honestly, separately. Guards are not in the takeoff: many regions require them once a deck is more than roughly 600 mm (24 in) above grade, and systems differ. For steps, the stair calculator works out risers, treads and the comfort check.
7. Finish and protect. Oils and stains are coverage jobs like paint — the paint calculator's area-and-coats maths transfers directly, with deck boards usually needing both faces done before fixing.