OUTSIDE BLUEPRINT
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SAMPLE OUTPUT · 12 × 16 FT TREX DECK

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Below is the complete shopping list and build guide for a 12×16 ft Trex Transcend — Spiced Rum deck with stairs and a guardrail — every board, bag, and bracket priced, then the build in order with dimensioned drawings. In the designer, the same documents are generated for your own design and update free as you edit it.

192 SQ FT16 FT ALONG THE HOUSE × 12 FT OUTLEDGER-ATTACHEDTREX TRANSCEND — SPICED RUM2x8 JOISTS @ 16" OC(2) 2x12 BEAM3 POSTS · 3 FOOTINGS4 FT STAIRS36" GUARDRAIL
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01SHOPPING LIST
20 ITEMS · 6 CATEGORIES
ITEMQTYEST. UNITEST. TOTAL
DECKING$2,066
Trex Transcend — Spiced Rum decking23 boards @ 20 ft (≈401 lin ft, 10% waste)23$82.64$1,900.80
Trex Transcend — Spiced Rum fascia2 boards (≈40 lin ft)2$82.50$165.00
FRAMING LUMBER$637
2x8 joists (interior)11 pcs @ 12 ft11$23.98$263.74
Beams — (2) 2x122 plies @ 16 ft (2x12)2$58.75$117.50
Posts — 6x63 pcs @ 8 ft3$48.00$144.00
Ledger — 2x81 pcs (≈16 lin ft)1$31.97$31.97
Rim / band joists — 2x82 pcs (≈40 lin ft)2$39.96$79.92
FOOTINGS$131
Concrete (60 lb bags)21 bags (7/footing × 3, holes 36" deep)21$6.25$131.25
STAIRS$246
Stair stringers — 2x125 pcs @ 8 ft (12" OC for composite treads)5$20.11$100.57
Stair treads — Trex Transcend — Spiced Rum4 treads @ 4 ft4$36.30$145.20
RAILINGS$621
Rail posts — 4x410 pcs @ 8 ft10$9.60$96.00
Top & bottom rails — 2x44 pcs (≈72 lin ft)4$18.47$73.87
Balusters (aluminum)7777$3.00$231.00
Rail post anchors1010$22.00$220.00
CONNECTORS & FASTENERS$211
Joist hangers1313$2.25$29.25
Hurricane ties1313$0.95$12.35
Post-beam caps33$16.00$48.00
Post bases33$24.00$72.00
Ledger fasteners (1/2" lag)1414$1.50$21.00
Deck screws / fasteners≈700700$0.04$28.00
20 ITEMS · PRICES: US-AVERAGE ESTIMATES ±15%TOTAL $3,911
02BUILD GUIDE
9 STEPS · 11 DRAWINGS
STEP 01

Before you begin

  1. 1.1Study the framing plan and cross-section below — every later step refers back to them. The plan is the top-down view (house at the top); the section cuts through one joist from footing to railing.
  2. 1.2Verify this plan against your locally adopted building code and pull the required permits before starting.
  3. 1.3Call 811 to have underground utilities located before any digging.
  4. 1.4Use pressure-treated lumber for all framing, and corrosion-resistant (hot-dip galvanized or stainless) fasteners and connectors. Any hardware touching treated lumber must be rated for it (G185 galvanized or stainless).
  5. 1.5Have your footing and framing inspected before you cover anything.
FIG 1.1
FIG 1.2
STEP 02

Footings & layout

  1. 2.1Stake out the 16 × 12 ft outline with string lines off the house wall on batter boards set a couple of feet outside the corners, so the strings survive the digging.
  2. 2.2Square the layout: check a 3-4-5 triangle at each end of the ledger (3 ft along one line, 4 ft along the other — the diagonal must be exactly 5 ft), then confirm the two overall diagonals of the outline match within 1/4".
  3. 2.3Mark 3 footing locations (1 beam line × 3 per line) with a plumb bob down from the string intersections — see the framing plan for where each beam line sits.
  4. 2.4Dig 3 holes to below the local frost line (≈36"+). Footings are sized 16" (≈18" round) for 1500 psf soil.
  5. 2.5Pour the concrete footings/piers and set galvanized post bases; check that all tops are level with each other.
FIG 2.1
FIG 2.2
STEP 03

Ledger board

  1. 3.1Remove the siding where the ledger lands and check the house band joist — it must be solid lumber, not just sheathing over floor trusses. If you find rot or can't confirm solid backing, stop and resolve it first (this connection is the #1 cause of deck collapse).
  2. 3.2Set the ledger height so the finished decking sits about 1–1.5" below the door threshold: threshold − decking thickness − joist depth gives the ledger's bottom edge. Strike a level line — don't trust the siding.
  3. 3.3Fasten the 2x8 ledger (~16 ft) to the band joist with 1/2" lag screws @ 15" OC, staggered top and bottom, each fastener ≥2" from the ledger edges and ends.
  4. 3.4Install flashing over and behind the ledger (up behind the housewrap, over the ledger top, then down its face) so water can never sit on the connection.
FIG 3.1
STEP 04

Posts & beams

  1. 4.1Stand 3 6x6 posts on the bases and brace each plumb in two directions with scrap 2x4s — leave the braces on until the joists are down.
  2. 4.2Build the beam: laminate 2 plies of 2x12 into (2) 2x12 with all crowns up, fastened with 2 rows of 10d nails @ 16" OC (or through-bolts). Any splice between plies must land over a post, and splices in adjacent plies must be offset.
  3. 4.3Set the beam on the posts at 8.0 ft post spacing; mark and cut the posts to height (a laser or water level beats a tape here); secure with post caps.
  4. 4.4Set the outer beam 1 ft in from the rim edge — the joists cantilever past it to the rim (within DCA-6's ¼-of-backspan limit).
FIG 4.1
STEP 05

Joists

  1. 5.1Mark the joist layout — 16" OC from one end — on the ledger and the outer rim at the same end so every joist runs parallel. Sight down each joist and set it crown up.
  2. 5.2Hang 13 2x8 joists @ 16" OC from the ledger using joist hangers, filling every hanger hole with the listed hanger nails (not deck screws — see the hardware detail).
  3. 5.3Secure each joist to the beam with hurricane ties.
  4. 5.4Install rim/band joists around the perimeter with (3) fasteners into each joist end, and check the frame is still square (equal diagonals) before decking.
  5. 5.5Install a row of solid 2x blocking between the joists at mid-span (spans over 8 ft) to stop twist and stiffen the floor.
FIG 5.1
FIG 5.2
STEP 06

Decking

  1. 6.1Lay Trex Transcend — Spiced Rum decking running parallel to the house, with ~0.25" gaps between boards — use spacers so the gaps stay consistent.
  2. 6.2Start the first board dead straight (snap a chalk line — don't trust the rim) and check every 4–5 boards that you're still parallel; make up small drift over several boards, never in one.
  3. 6.3Stagger any butt joints between rows and land every joint on a joist, with two fasteners per board at every bearing. Pre-drill within 1" of board ends to prevent splitting.
  4. 6.4Fasten with deck screws or hidden fasteners per the decking manufacturer; let the field boards run long, then snap a line and trim the whole edge in one saw pass.
  5. 6.5Wrap the exposed rim joists with Trex Transcend — Spiced Rum fascia board, flush with the decking surface.
FIG 6.1
STEP 07

Stairs

  1. 7.1Lay out the stair stringers (2x12) with a framing square using 7" rises and 11" runs down to grade at the front edge. Measure the total rise on site (deck surface to landing), divide by 7 and round to get the riser count, then divide back for the exact riser height.
  2. 7.2Cut one stringer, test-fit it against the deck, and use it as the template for the rest (stringers ≤ 18" apart for composite treads, ≤ 24" for 2x lumber). Code allows at most 3/8" variation between the tallest and shortest riser — the first cut sets all of them.
  3. 7.3Anchor the stringers to the deck framing with stringer hangers or a ledger strip; pour or set a footing/landing pad at the bottom and fasten the stringer feet to it.
  4. 7.4Install the treads (Trex Transcend — Spiced Rum) and risers; the stair width is 4 ft. Overhang the tread nosing 3/4–1 1/4" past the riser face.
FIG 7.1
STEP 08

Railings

  1. 8.1Mount 4x4 rail posts at the corners and ≤6 ft OC around the open edges. Through-bolt each post to the rim/joist framing with (2) 1/2" bolts — never notch the post, and add blocking behind the rim so the connection can't rack.
  2. 8.2Install the top and bottom rails at 36" guard height, keeping the bottom rail gap ≤4" above the decking.
  3. 8.3Fill with balusters spaced so a 4" sphere cannot pass (≤4" clear gaps) — divide each rail run evenly rather than accumulating a spacer, so the last gap doesn't come out wrong.
  4. 8.4Load-test every post (a guard must resist a 200-lb push at the top) before calling it done.
FIG 8.1
STEP 09

Finish

  1. 9.1Pass your framing and final inspections.
  2. 9.2Seal or finish the wood as recommended for your species and climate.
03YOUR DECK

Design your own deck — the list and guide follow it.

Designing is free. Set your size, height, decking, stairs, and railings in 3D, check the framing against span tables as you go, then unlock this same shopping list and build guide for your design with a one-time $19 purchase — priced for your ZIP, exportable to CSV, and updated free if you keep editing.

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