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A complete framing takeoff: joists, rim, beam, posts, footings, blocking and hangers.
With these inputs:
| Result | Value |
|---|---|
| Joists needed | 13 × 2x8 at 12.0 ft |
| Beam | 3-ply 2x8, one beam at 16.0 ft |
| Posts | 3 × 4x4 |
| Footings | 3 |
| Deck area | 192 sq ft |
| Joist lumber | 156 linear ft |
| Ledger | 16.0 ft of 2x8 pressure-treated |
| Rim and end joists | 40 linear ft |
| Beam lumber | 48 linear ft (3 plies × 1) |
| Post lumber | 12 linear ft of 4x4 |
| Blocking | 1 row, 12 pieces, 16 linear ft |
| Joist hangers | 13 |
| Post bases / caps | 3 bases, 3 caps |
| Total framing lumber | 288 linear ft |
This is a prescriptive takeoff for a rectangular deck at 16" on centre. Before you buy, check the joist size against the span table for your species — a 2x8 does not reach every depth — and confirm the beam ply count and post size with your building department, because beam sizing depends on the span between posts as well as the deck depth. Posts are cut long by a foot here so you have trim allowance. Footings must reach below the local frost line.
Every other framing calculator gives you one number. This one gives you the whole frame. Put in the deck size, joist spacing and height and it returns the joist count and lengths, the rim and end joists, how many plies the beam needs, the post and footing count, rows of blocking, and the hanger and hardware counts you take to the counter.
Divide the deck length in inches by the spacing and add one for the closing joist. A 16 ft deck at 16 inches on centre is 192 divided by 16, which is 12, plus one — 13 joists. At 12 inches on centre the same deck needs 17. The extra joists at tighter spacing are why composite decking costs more to frame as well as to buy.
Eight feet is the practical maximum along a beam for ordinary residential framing, and many builders use six. The real limit comes from the beam: a doubled 2x10 carrying a 12 ft deck depth will not reach 8 ft between posts in every species. Closer posts mean more footings but a smaller beam, and that trade is usually cheaper.
Codes generally require blocking or bridging when joists span more than a certain distance, and it is good practice regardless. Blocking stops the joists rolling under load, stiffens the whole frame noticeably underfoot, and gives you something to fasten to under a picture-frame border or a diagonal pattern. One row per 8 ft of span is the usual rule.
Attached is cheaper and uses less lumber, but the ledger connection is the deck's biggest structural risk and some wall types — brick veneer, stucco over foam, a cantilevered floor — cannot carry one at all. Freestanding needs a second beam and another row of footings, but it never loads the house, never leaks into the band joist, and often skips the hardest part of the inspection.
Need the whole roof at once? The free roofing calculator works out roof area, squares, shingle bundles, underlayment, drip edge, ridge cap and installed cost from one set of measurements.