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Decking worksheet

Grades 5–6

Solve each problem and show your work. Round answers to 2 decimal places where needed.

1.
Problem 1.
- Deck length (the direction the boards run): 22 ft
- Deck width (across the boards): 13 ft
- Board width (actual): 4.8 in
- Gap between boards: 0.15 in
- Board length: 16 ft
- Joist spacing (on center): 16 in
- Extra boards for defects: 4%
- Fastening: Face screws (2 per joist)
Find: Deck boards (16 ft)
Answer
2.
Problem 2.
- Deck length (the direction the boards run): 19 ft
- Deck width (across the boards): 14 ft
- Board width (actual): 4.8 in
- Gap between boards: 0.14 in
- Board length: 13 ft
- Joist spacing (on center): 12 in
- Extra boards for defects: 5%
- Fastening: Face screws (2 per joist)
Find: Deck boards (13 ft)
Answer
3.
Problem 3.
- Deck length (the direction the boards run): 18 ft
- Deck width (across the boards): 16 ft
- Board width (actual): 4.6 in
- Gap between boards: 0.25 in
- Board length: 18 ft
- Joist spacing (on center): 24 in
- Extra boards for defects: 5%
- Fastening: Face screws (2 per joist)
Find: Deck boards (18 ft)
Answer
4.
Problem 4.
- Deck length (the direction the boards run): 17 ft
- Deck width (across the boards): 14 ft
- Board width (actual): 5.4 in
- Gap between boards: 0.19 in
- Board length: 11 ft
- Joist spacing (on center): 16 in
- Extra boards for defects: 5%
- Fastening: Face screws (2 per joist)
Find: Deck boards (11 ft)
Answer
5.
Problem 5.
- Deck length (the direction the boards run): 20 ft
- Deck width (across the boards): 7 ft
- Board width (actual): 6.4 in
- Gap between boards: 0.225 in
- Board length: 10 ft
- Joist spacing (on center): 12 in
- Extra boards for defects: 5%
- Fastening: Hidden clips (1 per joist)
Find: Deck boards (10 ft)
Answer
6.
Problem 6.
- Deck length (the direction the boards run): 16 ft
- Deck width (across the boards): 9 ft
- Board width (actual): 5.4 in
- Gap between boards: 0.17 in
- Board length: 15 ft
- Joist spacing (on center): 24 in
- Extra boards for defects: 5%
- Fastening: Hidden clips (1 per joist)
Find: Deck boards (15 ft)
Answer
7.
Problem 7.
- Deck length (the direction the boards run): 17 ft
- Deck width (across the boards): 11 ft
- Board width (actual): 6.4 in
- Gap between boards: 0.15 in
- Board length: 18 ft
- Joist spacing (on center): 12 in
- Extra boards for defects: 4%
- Fastening: Hidden clips (1 per joist)
Find: Deck boards (18 ft)
Answer
8.
Problem 8.
- Deck length (the direction the boards run): 18 ft
- Deck width (across the boards): 10 ft
- Board width (actual): 6 in
- Gap between boards: 0.23 in
- Board length: 15 ft
- Joist spacing (on center): 12 in
- Extra boards for defects: 5%
- Fastening: Hidden clips (1 per joist)
Find: Deck boards (15 ft)
Answer
9.
Problem 9.
- Deck length (the direction the boards run): 14 ft
- Deck width (across the boards): 10 ft
- Board width (actual): 4 in
- Gap between boards: 0.2 in
- Board length: 21 ft
- Joist spacing (on center): 12 in
- Extra boards for defects: 6%
- Fastening: Hidden clips (1 per joist)
Find: Deck boards (21 ft)
Answer
10.
Problem 10.
- Deck length (the direction the boards run): 11 ft
- Deck width (across the boards): 10 ft
- Board width (actual): 6.5 in
- Gap between boards: 0.17 in
- Board length: 18 ft
- Joist spacing (on center): 16 in
- Extra boards for defects: 5%
- Fastening: Hidden clips (1 per joist)
Find: Deck boards (18 ft)
Answer

Answer key: Decking worksheet

1. Deck boards (16 ft): 67
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{156 + 0.15}{(4.8 + 0.15)}$ $= 31.5455$ $= rounded up: 32$
2. Boards per row = deck length ÷ 16 ft board length, rounded up
  $\frac{22}{16}$ $= 1.375$ $= rounded up: 2$
3. Boards = rows × boards per row, plus 4% for defects, rounded up
  $32 \times 2 \times 1 + 0.04$ $= 66.56$ $= rounded up: 67$
4. Linear feet of decking on the deck = rows × deck length
  $32 \times 22$ $= 704 ft$
5. Joists = deck length in inches ÷ 16 in spacing, rounded up, plus one for the far end
  $\frac{264}{16} + 1$ $= rounded: 18$
6. Screws = rows × joists × 2 per crossing
  $32 \times 18 \times 2$ $= 1,152$
2. Deck boards (13 ft): 74
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{168 + 0.14}{(4.8 + 0.14)}$ $= 34.0364$ $= rounded up: 35$
2. Boards per row = deck length ÷ 13 ft board length, rounded up
  $\frac{19}{13}$ $= 1.4615$ $= rounded up: 2$
3. Boards = rows × boards per row, plus 5% for defects, rounded up
  $35 \times 2 \times 1 + 0.05$ $= 73.5$ $= rounded up: 74$
4. Linear feet of decking on the deck = rows × deck length
  $35 \times 19$ $= 665 ft$
5. Joists = deck length in inches ÷ 12 in spacing, rounded up, plus one for the far end
  $\frac{228}{12} + 1$ $= rounded: 20$
6. Screws = rows × joists × 2 per crossing
  $35 \times 20 \times 2$ $= 1,400$
3. Deck boards (18 ft): 42
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{192 + 0.25}{(4.6 + 0.25)}$ $= 39.6392$ $= rounded up: 40$
2. Boards per row = deck length ÷ 18 ft board length, rounded up
  $\frac{18}{18}$ $= 1$ $= rounded up: 1$
3. Boards = rows × boards per row, plus 5% for defects, rounded up
  $40 \times 1 \times 1 + 0.05$ $= 42$ $= rounded up: 42$
4. Linear feet of decking on the deck = rows × deck length
  $40 \times 18$ $= 720 ft$
5. Joists = deck length in inches ÷ 24 in spacing, rounded up, plus one for the far end
  $\frac{216}{24} + 1$ $= rounded: 10$
6. Screws = rows × joists × 2 per crossing
  $40 \times 10 \times 2$ $= 800$
4. Deck boards (11 ft): 66
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{168 + 0.19}{(5.4 + 0.19)}$ $= 30.0877$ $= rounded up: 31$
2. Boards per row = deck length ÷ 11 ft board length, rounded up
  $\frac{17}{11}$ $= 1.5455$ $= rounded up: 2$
3. Boards = rows × boards per row, plus 5% for defects, rounded up
  $31 \times 2 \times 1 + 0.05$ $= 65.1$ $= rounded up: 66$
4. Linear feet of decking on the deck = rows × deck length
  $31 \times 17$ $= 527 ft$
5. Joists = deck length in inches ÷ 16 in spacing, rounded up, plus one for the far end
  $\frac{204}{16} + 1$ $= rounded: 14$
6. Screws = rows × joists × 2 per crossing
  $31 \times 14 \times 2$ $= 868$
5. Deck boards (10 ft): 28
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{84 + 0.225}{(6.4 + 0.225)}$ $= 12.7132$ $= rounded up: 13$
2. Boards per row = deck length ÷ 10 ft board length, rounded up
  $\frac{20}{10}$ $= 2$ $= rounded up: 2$
3. Boards = rows × boards per row, plus 5% for defects, rounded up
  $13 \times 2 \times 1 + 0.05$ $= 27.3$ $= rounded up: 28$
4. Linear feet of decking on the deck = rows × deck length
  $13 \times 20$ $= 260 ft$
5. Joists = deck length in inches ÷ 12 in spacing, rounded up, plus one for the far end
  $\frac{240}{12} + 1$ $= rounded: 21$
6. Hidden clips = rows × joists × 1 per crossing
  $13 \times 21 \times 1$ $= 273$
6. Deck boards (15 ft): 42
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{108 + 0.17}{(5.4 + 0.17)}$ $= 19.4201$ $= rounded up: 20$
2. Boards per row = deck length ÷ 15 ft board length, rounded up
  $\frac{16}{15}$ $= 1.0667$ $= rounded up: 2$
3. Boards = rows × boards per row, plus 5% for defects, rounded up
  $20 \times 2 \times 1 + 0.05$ $= 42$ $= rounded up: 42$
4. Linear feet of decking on the deck = rows × deck length
  $20 \times 16$ $= 320 ft$
5. Joists = deck length in inches ÷ 24 in spacing, rounded up, plus one for the far end
  $\frac{192}{24} + 1$ $= rounded: 9$
6. Hidden clips = rows × joists × 1 per crossing
  $20 \times 9 \times 1$ $= 180$
7. Deck boards (18 ft): 22
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{132 + 0.15}{(6.4 + 0.15)}$ $= 20.1756$ $= rounded up: 21$
2. Boards per row = deck length ÷ 18 ft board length, rounded up
  $\frac{17}{18}$ $= 0.9444$ $= rounded up: 1$
3. Boards = rows × boards per row, plus 4% for defects, rounded up
  $21 \times 1 \times 1 + 0.04$ $= 21.84$ $= rounded up: 22$
4. Linear feet of decking on the deck = rows × deck length
  $21 \times 17$ $= 357 ft$
5. Joists = deck length in inches ÷ 12 in spacing, rounded up, plus one for the far end
  $\frac{204}{12} + 1$ $= rounded: 18$
6. Hidden clips = rows × joists × 1 per crossing
  $21 \times 18 \times 1$ $= 378$
8. Deck boards (15 ft): 42
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{120 + 0.23}{(6 + 0.23)}$ $= 19.2986$ $= rounded up: 20$
2. Boards per row = deck length ÷ 15 ft board length, rounded up
  $\frac{18}{15}$ $= 1.2$ $= rounded up: 2$
3. Boards = rows × boards per row, plus 5% for defects, rounded up
  $20 \times 2 \times 1 + 0.05$ $= 42$ $= rounded up: 42$
4. Linear feet of decking on the deck = rows × deck length
  $20 \times 18$ $= 360 ft$
5. Joists = deck length in inches ÷ 12 in spacing, rounded up, plus one for the far end
  $\frac{216}{12} + 1$ $= rounded: 19$
6. Hidden clips = rows × joists × 1 per crossing
  $20 \times 19 \times 1$ $= 380$
9. Deck boards (21 ft): 31
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{120 + 0.2}{(4 + 0.2)}$ $= 28.619$ $= rounded up: 29$
2. Boards per row = deck length ÷ 21 ft board length, rounded up
  $\frac{14}{21}$ $= 0.6667$ $= rounded up: 1$
3. Boards = rows × boards per row, plus 6% for defects, rounded up
  $29 \times 1 \times 1 + 0.06$ $= 30.74$ $= rounded up: 31$
4. Linear feet of decking on the deck = rows × deck length
  $29 \times 14$ $= 406 ft$
5. Joists = deck length in inches ÷ 12 in spacing, rounded up, plus one for the far end
  $\frac{168}{12} + 1$ $= rounded: 15$
6. Hidden clips = rows × joists × 1 per crossing
  $29 \times 15 \times 1$ $= 435$
10. Deck boards (18 ft): 20
1. Rows of boards = (deck width in inches + gap) ÷ (board width + gap), rounded up
  $\frac{120 + 0.17}{(6.5 + 0.17)}$ $= 18.0165$ $= rounded up: 19$
2. Boards per row = deck length ÷ 18 ft board length, rounded up
  $\frac{11}{18}$ $= 0.6111$ $= rounded up: 1$
3. Boards = rows × boards per row, plus 5% for defects, rounded up
  $19 \times 1 \times 1 + 0.05$ $= 19.95$ $= rounded up: 20$
4. Linear feet of decking on the deck = rows × deck length
  $19 \times 11$ $= 209 ft$
5. Joists = deck length in inches ÷ 16 in spacing, rounded up, plus one for the far end
  $\frac{132}{16} + 1$ $= rounded: 10$
6. Hidden clips = rows × joists × 1 per crossing
  $19 \times 10 \times 1$ $= 190$