Note: The span tables included in this appendix include only the most common species, spans and grades of lumber. For other species, spans and grades of lumber, refer to the National Building Code of Canada (National Research Council) or The Span Book (Canadian Wood Council).

Table 15
Maximum Spans for Floor Joists - General Cases 1, 2

 

Maximum Span, ft.-in. (m)

Joist Spacing, in. (mm)
Commercial Designation
Grade

  Joist Size, ft. (m)

  With Strapping

With Bridging
With Strapping and Bridging

12
(300)

16
(400)

24
(600)

12
(300)

16
(400)

24
(600)

12
(300)

16
(400)

24
(600)

Douglas fir – larch (includes Douglas fir and western larch) No. 1 and No. 2

2x6

10–2

9–7

8–7

10–10

9–10

8–7

10–10

9–10

8–7

(38x140)

(3.09)

(2.91)

(2.62)

(3.29)

(2.99)

(2.62)

(3.29)

(2.99)

(2.62)

2x8

12–2

11–7

11–0

13–1

12–4

11–3

13–9

12–10

11–3

(38x184)

(3.71)

(3.53)

(3.36)

(4.00)

(3.76)

(3.44)

(4.19)

(3.90)

(3.44)

2x10

14–4

13–8

13–0

15–3

14–4

13–6

15–10

14–10

13–10

(38x235)

(4.38)

(4.16)

(3.96)

(4.66)

(4.38)

(4.11)

(4.84)

(4.51)

(4.20)

2x12

16–5

15–7

14–10

17–2

16–2

15–3

17–10

16–7

15–6

(38x286)

(4.99)

(4.75)

(4.52)

(5.26)

(4.94)

(4.65)

(5.43)

(5.06)

(4.72)

Hem – fir (includes western hemlock and amabilis fir) No. 1 and No. 2

2x6

10-2

9–7

8–7

10–10

9–10

8–7

10–10

9–10

8–7

(38x140)

(3.09)

(2.91)

(2.62)

(3.29)

(2.99)

(2.62)

(3.29)

(2.99)

(2.62)

2x8

12–2

11–7

11–0

13–1

12–4

11–3

13–9

12–10

11–3

(38x184)

(3.71)

(3.53)

(3.36)

(4.00)

(3.76)

(3.44)

(4.19)

(3.90)

(3.44)

2x10

14–4

13–8

13–0

15–3

14–4

13–6

15–10

14–10

13–10

(38x235)

(4.38)

(4.16)

(3.96)

(4.66)

(4.38)

(4.11)

(4.84)

(4.51)

(4.20)

2x12

16–5

15–7

14–10

17–2

16–2

15–3

17–10

16–7

15–6

(38x286)

(4.99)

(4.75)

(4.52)

(5.26)

(4.94)

(4.65)

(5.43)

(5.06)

(4.72)

Spruce – pine – fir (includes spruce [all species except coast sitka spruce], jack pine, lodgepole pine, balsam fir and alpine fir)  

2x6

9–7

8–11

8–2

10–4

9–4

8–2

10–4

9–4

8–2

(38x140)

(2.92)

(2.71)

(2.49)

(3.14)

(2.85)

(2.49)

(3.14)

(2.85)

(2.49)

2x8

11–7

11–0

10–6

12–5

11–9

10–9

13–1

12–2

10–9

(38x184)

(3.54)

(3.36)

(3.20)

(3.81)

(3.58)

(3.27)

(3.99)

(3.72)

(3.27)

2x10

13–8

13–0

12–4

14–6

13–8

12–10

15–1

14–1

13–2

(38x235)

(4.17)

(3.96)

(3.77)

(4.44)

(4.17)

(3.92)

(4.60)

(4.29)

(4.00)

2x12

15–7

14–10

14–1

16–4

15–5

14–6

17–0

15–10

14–9

(38x286)

(4.75)

(4.52)

(4.30)

(5.01)

(4.71)

(4.42)

(5.17)

(4.82)

(4.49)

Northern species (includes any Canadian species covered by the NLGA Standard Grading Rules) No. 1 and No. 2

2x6

8–3

7–8

7–1

9–3

8–5

7–5

9–4

8–5

7–5

(38x140)

(2.51)

(2.33)

(2.16)

(2.83)

(2.57)

(2.25)

(2.83)

(2.57)

(2.25)

2x8

10–6

10–0

9–4

11–3

10–7

9–8

11–10

11–0

9–8

(38x184)

(3.19)

(3.04)

(2.84)

(3.44)

(3.23)

(2.96)

(3.60)

(3.36)

(2.96)

2x10

12–4

11–9

11–2

13–1

12–4

11–7

13–8

12–9

11–10

(38x235)

(3.76)

(3.58)

(3.41)

(4.01)

(3.77)

(3.54)

(4.16)

(3.88)

(3.62)

2x12

14–1

13–5

12–9

14–9

13–11

13–1

15–4

14–4

13–4

(38x286)

(4.29)

(4.08)

(3.88)

(4.53)

(4.25)

(4.00)

(4.67)

(4.35)

(4.06)

 

See also:

Note to Table 15

1. Spans apply only where the floors serve residential areas.

2. Subfloor must comply with minimum requirements from tables 17 and 18.

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