Deck Joist Span Chart (Canada)

Canada

Find the maximum span for your deck joists by size, species, spacing and treatment, from the Canadian Wood Council's deck span guide.

Your joists

1. Lumber

Most pressure treated S-P-F and Hem-Fir sold in Canada is incised: look for small slits on the faces.

Result

0

From the CWC deck span guide

1.9 kPa live load, 0.5 kPa dead load, No.2 or better, L/360. Spans are clear spans between supports. Where guards are required, joists and rim boards must be at least 2 × 8.

Where these spans come from

The spans are copied exactly from the Canadian Wood Council's Prescriptive Residential Exterior Wood Deck Span Guide (Revision 1, 2016), the only free Canadian table written specifically for decks. Its design basis, as the guide states it:

  • CSA O86-14 and NBC 2015
  • Live load 1.9 kPa (40 psf), dead load 0.5 kPa (10 psf)
  • No.2 or better lumber, live load deflection limit L/360
  • Wet service factors applied; incised tables also apply treatment factors

Check your snow load first. NBC 2020 Article 9.4.2.3 says a deck must carry the roof snow load or 1.9 kPa, whichever is greater. These tables only cover 1.9 kPa. Of the 105 cities in our snow load table, 26 have a higher roof load, including Burnaby, North Vancouver, Prince George, Nelson. Your building department decides which table it accepts.

Pressure treated, incised lumber (CWC Tables 3a and 3b)

Joists at 8 in (200 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 7' 6"
2.30 m 		7' 6"
2.30 m 		7' 2"
2.19 m 		6' 6"
1.98 m
2 × 6 11' 10"
3.61 m 		11' 10"
3.61 m 		11' 3"
3.44 m 		10' 2"
3.11 m
2 × 8 14' 11"
4.54 m 		15' 7"
4.75 m 		14' 10"
4.52 m 		13' 0"
3.96 m
2 × 10 18' 3" *
5.55 m 		19' 1" *
5.82 m 		18' 11" *
5.78 m 		15' 11"
4.84 m
2 × 12 21' 2" *
6.44 m 		22' 2" *
6.76 m 		22' 11" *
7.00 m 		18' 5" *
5.62 m

Joists at 12 in (300 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 6' 7"
2.01 m 		6' 7"
2.01 m 		6' 3"
1.91 m 		5' 8"
1.73 m
2 × 6 10' 0"
3.05 m 		10' 4"
3.16 m 		9' 10"
3.01 m 		8' 9"
2.66 m
2 × 8 12' 2"
3.71 m 		12' 9"
3.89 m 		13' 0"
3.95 m 		10' 7"
3.23 m
2 × 10 14' 10"
4.53 m 		15' 7"
4.75 m 		16' 2" *
4.92 m 		13' 0"
3.95 m
2 × 12 17' 3" *
5.26 m 		18' 1" *
5.52 m 		18' 9" *
5.71 m 		15' 1"
4.58 m

Joists at 16 in (400 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 6' 0"
1.82 m 		6' 0"
1.82 m 		5' 8"
1.74 m 		5' 2"
1.57 m
2 × 6 8' 8"
2.64 m 		9' 1"
2.77 m 		9' 0"
2.73 m 		7' 7"
2.30 m
2 × 8 10' 6"
3.21 m 		11' 1"
3.37 m 		11' 5"
3.49 m 		9' 2"
2.80 m
2 × 10 12' 11"
3.92 m 		13' 6"
4.12 m 		14' 0"
4.26 m 		11' 3"
3.42 m
2 × 12 14' 11"
4.55 m 		15' 8"
4.78 m 		16' 3" *
4.95 m 		13' 0"
3.97 m

Joists at 24 in (600 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 4' 11"
1.51 m 		5' 2"
1.58 m 		5' 0"
1.52 m 		4' 4"
1.32 m
2 × 6 7' 1"
2.15 m 		7' 5"
2.26 m 		7' 8"
2.34 m 		6' 2"
1.88 m
2 × 8 8' 7"
2.62 m 		9' 0"
2.75 m 		9' 4"
2.85 m 		7' 6"
2.28 m
2 × 10 10' 6"
3.20 m 		11' 0"
3.36 m 		11' 5"
3.48 m 		9' 2"
2.79 m
2 × 12 12' 2"
3.72 m 		12' 10"
3.90 m 		13' 3"
4.04 m 		10' 8"
3.24 m

Not incised lumber (CWC Tables 2a and 2b)

Joists at 8 in (200 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 7' 8"
2.34 m 		7' 8"
2.34 m 		7' 4"
2.23 m 		6' 7"
2.01 m
2 × 6 12' 1"
3.68 m 		12' 1"
3.68 m 		11' 6"
3.50 m 		10' 4"
3.16 m
2 × 8 15' 10"
4.83 m 		15' 10"
4.83 m 		15' 1"
4.60 m 		13' 8"
4.15 m
2 × 10 19' 9" *
6.02 m 		20' 3" *
6.17 m 		19' 3" *
5.88 m 		17' 3" *
5.25 m
2 × 12 22' 11" *
6.99 m 		24' 0" *
7.33 m 		23' 5" *
7.15 m 		20' 0" *
6.09 m

Joists at 12 in (300 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 6' 8"
2.04 m 		6' 8"
2.04 m 		6' 5"
1.94 m 		5' 9"
1.76 m
2 × 6 10' 6"
3.21 m 		10' 6"
3.21 m 		10' 0"
3.06 m 		9' 1"
2.76 m
2 × 8 13' 2"
4.02 m 		13' 10"
4.22 m 		13' 2"
4.02 m 		11' 6"
3.50 m
2 × 10 16' 2" *
4.92 m 		16' 11" *
5.16 m 		16' 10" *
5.13 m 		14' 1"
4.29 m
2 × 12 18' 9" *
5.70 m 		19' 8" *
5.98 m 		20' 4" *
6.20 m 		16' 4" *
4.97 m

Joists at 16 in (400 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 6' 1"
1.85 m 		6' 1"
1.85 m 		5' 10"
1.77 m 		5' 3"
1.60 m
2 × 6 9' 5"
2.86 m 		9' 7"
2.92 m 		9' 1"
2.78 m 		8' 2"
2.49 m
2 × 8 11' 5"
3.48 m 		12' 0"
3.65 m 		12' 0"
3.65 m 		9' 11"
3.04 m
2 × 10 14' 0"
4.26 m 		14' 8"
4.47 m 		15' 2"
4.62 m 		12' 2"
3.71 m
2 × 12 16' 2" *
4.94 m 		17' 0" *
5.18 m 		17' 7" *
5.37 m 		14' 2"
4.31 m

Joists at 24 in (600 mm) on centre

Joist DF-LH-FS-P-FNor
2 × 4 5' 4"
1.62 m 		5' 4"
1.62 m 		5' 1"
1.54 m 		4' 7"
1.39 m
2 × 6 7' 8"
2.34 m 		8' 0"
2.45 m 		8' 0"
2.43 m 		6' 8"
2.04 m
2 × 8 9' 4"
2.84 m 		9' 9"
2.98 m 		10' 2"
3.09 m 		8' 2"
2.48 m
2 × 10 11' 5"
3.48 m 		12' 0"
3.65 m 		12' 5"
3.78 m 		9' 11"
3.03 m
2 × 12 13' 3"
4.03 m 		13' 11"
4.23 m 		14' 4"
4.38 m 		11' 6"
3.52 m

* Joist stock longer than 16 ft (4.9 m) is not typically available. Species: DF-L is Douglas Fir and Western Larch; H-F is Western Hemlock and Amabilis Fir; S-P-F covers the spruces, lodgepole and jack pine, and alpine and balsam fir; Northern covers cedars, eastern hemlock, white and red pine, aspen and others.

Rules that come with the table

  • Guards mean 2 × 8 minimum. Where guards are required, joists and rim boards must be at least nominal 2 × 8.
  • Two spans at most. The guide's tables are not valid if joists run continuously over more than two supports.
  • Not covered: footings, guards, attaching the deck to the house, and lateral bracing.
  • Footings: see frost depth and footing depth.

Common questions

How far can a 2x8 deck joist span in Canada?
In pressure treated, incised S-P-F at 16 in centres, the CWC deck span guide gives 11' 5". Not incised S-P-F (for example untreated) gets 12' 0".
How far can a 2x10 deck joist span?
Incised S-P-F at 16 in centres: 14' 0". At 12 in centres it rises to 16' 2".
How far can a 2x6 deck joist span?
Incised S-P-F at 16 in centres: 9' 0". Note the guide requires joists and rim boards of at least 2 × 8 wherever the deck needs a guard (more than 600 mm above ground).
How far can a 2x12 deck joist span?
Incised S-P-F at 16 in centres: 16' 3". Joist stock over 16 ft is not typically available, which can limit longer spans in practice.
Do these span tables work everywhere in Canada?
No. They are designed for a 1.9 kPa live load. NBC 2020 Article 9.4.2.3 requires a deck to carry the roof snow load where that is higher, so in snowier places such as Quebec City (2.58 kPa) or St. John's (2.3 kPa) you need other tables or an engineer. Use our snow load lookup to check your city.
Should I use the incised or not incised table?
Most pressure treated S-P-F and Hem-Fir sold in Canada is incised: you can see rows of small slits on the faces. Incising lets the preservative in but weakens the wood slightly, so the incised table gives shorter spans. Use the not incised table for untreated, naturally durable species such as cedar.
How is joist span measured?
As the clear span between supports, from the inside face of one support to the inside face of the next. A cantilever beyond the beam is limited separately; the tables list the maximum for each size.