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Siding calculator

13.25 squares · 159 pieces1,325.00 SF net
Walls
1,260.00 SF
Gables
225.00 SF
Windows and doors
− 160.00 SF
Net area
1,325.00 SF
Pieces
159 pieces (8.33 SF each)
Starter strip
140' 0"
J-channel / trim around openings
172' 8"
Gable rakes
67' 1"
Outside corners
4 × wall height = 36' 0"

These sketches are here to help you order material and price the work quickly. They are not engineered or shop drawings — always build from your approved project drawings.

Walls

Wall length is all the walls being sided, end to end (the perimeter for a whole house).

Windows and doors

Product

Exposure is the face that shows. Fiber cement: plank width − 1¼" lap. Vinyl: from the carton (double 4" = 8"). Check the length on your carton.

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  1. Walls
    wall length × wall height
    140' 0" × 9' 0" = 1,260.00 SF
  2. Gables
    gables × width × height ÷ 2
    2 × 30' 0" × 7' 6" ÷ 2 = 225.00 SF
  3. Windows and doors
    count × width × height, each
    10 × 3' 0" × 4' 0" + 2 × 3' 0" × 6' 8" = 160.00 SF
  4. Net siding area
    walls + gables − openings
    1,260.00 SF + 225.00 SF − 160.00 SF = 1,325.00 SF
  5. Squares
    net SF ÷ 100
    1,325.00 SF ÷ 100 = 13.25
  6. One piece covers
    exposure × piece length
    8" × 12' 6" = 8.33 SF
  7. Pieces
    net SF ÷ SF per piece, rounded up
    1,325.00 SF ÷ 8.33 SF = 159
  8. Trim around openings (J-channel)
    windows: 2 × (width + height); doors: 2 × height + width
    10 windows + 2 doors = 172.7
  9. Gable rakes
    gables × 2 × √((width ÷ 2)² + height²)
    2 × 2 × √(( 30' 0" ÷ 2)² + 7' 6" ²) = 67.1

Where the numbers come from

  • Exposure: Fiber-cement plank: plank width − 1¼" lap (8¼" plank = 7" exposure) · double 4" vinyl: 8" exposure, 12'6" panels (8.33 SF each, 24 = 2 squares)James Hardie HardiePlank instructions (and IRC R703.10.2) call for at least a 1¼" overlap, so the exposure is the plank width less 1¼" — 8¼" = 7", 6¼" = 5". Vinyl exposure is set by the panel: Owens Corning lists double 4" panels at 8" exposure, 12'6" long, 2 squares per carton, and double 5" at 12' long (https://sweets.construction.com/swts_content_files/40974/P26544.htm). Check your product's carton — lengths vary by brand.Source
  • Board and batten: Boards = wall length ÷ (board width + gap), rounded up · one batten over each gapGeometry only. The last board of each wall meets a corner, so it gets corner trim instead of a batten. Boards run past windows and doors and are cut around them — openings are not deducted. Piece counts assume boards are not spliced up the wall more than needed (wall height ÷ piece length, rounded up).

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Squares and pieces of lap siding (vinyl or fiber cement), or boards and battens — with the trim.