Canadian Rebar Sizes — CSA G30.18 Bar Dimensions and Properties
Reinforcing steel bars for Canadian concrete construction conform to CSA G30.18 (Carbon Steel Bars for Concrete Reinforcement) and are designed in accordance with CSA A23.3 (Design of Concrete Structures). Canadian rebar uses metric designations (10M through 55M) where the number indicates the nominal bar diameter in millimetres.
Canadian rebar grades include 400W (standard grade, f_y = 400 MPa) and 500W (high-strength grade, f_y = 500 MPa). Grade 400W is the default for most reinforced concrete construction in Canada, equivalent to ASTM A615 Gr. 60 but with weldability requirements specified by the "W" suffix. Grade 500W provides 25% higher yield strength for economy in heavily loaded members.
CSA G30.18 Bar Size Table
CSA G30.18-09 Table 1 specifies the following standard bar dimensions and mechanical properties:
| Bar Size | Nominal Diameter (mm) | Nominal Area (mm^2) | Mass per Metre (kg/m) | Perimeter (mm) |
|---|---|---|---|---|
| 10M | 11.3 | 100 | 0.785 | 35.5 |
| 15M | 16.0 | 200 | 1.570 | 50.3 |
| 20M | 19.5 | 300 | 2.355 | 61.3 |
| 25M | 25.2 | 500 | 3.925 | 79.2 |
| 30M | 29.9 | 700 | 5.495 | 93.9 |
| 35M | 35.7 | 1000 | 7.850 | 112.2 |
| 45M | 43.7 | 1500 | 11.78 | 137.3 |
| 55M | 49.5 | 2000 | 15.70 | 155.5 |
The nominal area follows the relationship A = pi x d^2 / 4, rounding to the nearest 100 mm^2 for larger bars. Mass per metre = A x 7850 kg/m^3. The bar diameter tolerance per CSA G30.18 is +/- 0.5 mm for 10M-20M and +/- 0.6 mm for 25M-55M.
Comparison with US Imperial Rebar Sizes
Canadian metric bars are similar to but not interchangeable with US imperial bars:
| Canadian Size | US Size | Diameter (mm) | Area (mm^2) | Notes |
|---|---|---|---|---|
| 10M | #3 | 11.3 / 9.5 | 100 / 71 | Canadian 10M larger than US #3 |
| 15M | #5 | 16.0 / 15.9 | 200 / 200 | Near equivalent |
| 20M | #6 | 19.5 / 19.1 | 300 / 284 | Canadian slightly larger |
| 25M | #8 | 25.2 / 25.4 | 500 / 510 | Near equivalent |
| 30M | #9 | 29.9 / 28.7 | 700 / 645 | Canadian larger |
| 35M | #10 | 35.7 / 32.3 | 1000 / 819 | Canadian significantly larger |
| 45M | #14 | 43.7 / 43.0 | 1500 / 1452 | Near equivalent |
| 55M | #18 | 49.5 / 57.3 | 2000 / 2581 | No direct US equivalent |
For projects designed to CSA A23.3, metric bars must be specified. Using US imperial bars as a substitute requires verification that the area and development length requirements are satisfied.
Grade 400W and 500W Mechanical Properties
CSA G30.18 specifies the following mechanical properties for standard rebar grades:
| Property | Grade 400W | Grade 500W |
|---|---|---|
| Minimum yield strength f_y | 400 MPa | 500 MPa |
| Minimum tensile strength f_u | 540 MPa | 620 MPa |
| Minimum elongation (200 mm gauge length) | 12% | 10% |
| Minimum elongation (50 mm gauge length) | 18% | 15% |
| Bend test mandrel diameter | 4d to 6d (size dependent) | 6d to 8d (size dependent) |
| Re-bend test | 160 deg C aging, 160 deg bend | 160 deg C aging, 160 deg bend |
| Carbon equivalent CEV (max) | 0.55% | 0.60% |
| Yield ratio f_y/f_u (actual, typical) | 1.35 | 1.24 |
The "W" suffix indicates weldability — the steel has a controlled carbon equivalent (CEV <= 0.55% for 400W, <= 0.60% for 500W) and weldability certification per CSA W186. This is an important difference from ASTM A615 Gr. 60, which does not have a guaranteed weldability requirement.
Development Length per CSA A23.3
For tension development of deformed bars per CSA A23.3:19 Clause 12.2, the basic development length L_d is:
L_d = 0.45 x k_1 x k_2 x k_3 x k_4 x (f_y / sqrt(f'_c)) x d_b
Where:
- k_1 = bar location factor (1.0 for bottom bars, 1.3 for top bars with > 300 mm concrete below)
- k_2 = coating factor (1.0 for uncoated, 1.2 for epoxy-coated with cover < 3d_b)
- k_3 = concrete density factor (1.0 for normal weight, 1.3 for semi-low density, 1.4 for structural low density)
- k_4 = bar size factor (0.8 for 10M-20M, 1.0 for 25M-30M, 1.4 for 35M-55M)
- f'_c = specified concrete compressive strength (MPa)
- d_b = nominal bar diameter (mm)
Example: Development length for a 25M bottom bar (uncoated) in 30 MPa normal-weight concrete:
L_d = 0.45 x 1.0 x 1.0 x 1.0 x 1.0 x (400 / sqrt(30)) x 25.2 L_d = 0.45 x (400 / 5.48) x 25.2 L_d = 0.45 x 73.0 x 25.2 L_d = 828 mm
Standard Hook and Bend Dimensions
Per CSA A23.3:19 Clause 12.5, standard hooks for seismic and non-seismic applications:
| Bar Size | Minimum Inside Bend Diameter | Standard Hook Extension | Seismic Hook Extension |
|---|---|---|---|
| 10M | 4d_b = 45 mm | 150 mm | 200 mm |
| 15M | 4d_b = 64 mm | 150 mm | 200 mm |
| 20M | 6d_b = 117 mm | 200 mm | 250 mm |
| 25M | 8d_b = 202 mm | 250 mm | 300 mm |
| 30M | 8d_b = 239 mm | 350 mm | 400 mm |
| 35M | 10d_b = 357 mm | 400 mm | 450 mm |
Seismic hooks (135-degree bend with extension) are required for hoops and cross-ties in seismic-force-resisting systems per CSA A23.3:19 Clause 21.3.
Worked Example — Tension Reinforcement for a Simply Supported Beam
Given: A rectangular concrete beam, b = 350 mm, d = 500 mm, spanning 8.0 m. Factored moment M_f = 350 kN.m. f'_c = 30 MPa, f_y = 400 MPa (Grade 400W). Determine the required tension reinforcement.
Solution per CSA A23.3:19:
Assume the neutral axis depth a = d - sqrt(d^2 - 2 x M_f / (0.85 x phi_c x f'_c x b))
phi_c = 0.65 per CSA A23.3 Clause 8.4.2
a = 500 - sqrt(500^2 - 2 x 350 x 10^6 / (0.65 x 0.85 x 30 x 350)) a = 500 - sqrt(250,000 - 2 x 350 x 10^6 / (5,801)) a = 500 - sqrt(250,000 - 120,670) a = 500 - 359.6 = 140.4 mm
Required steel area A_s = M_f / (phi_s x f_y x (d - a/2))
phi_s = 0.85 per CSA A23.3 Clause 8.4.3
A_s = 350 x 10^6 / (0.85 x 400 x (500 - 140.4/2)) A_s = 350 x 10^6 / (0.85 x 400 x 429.8) A_s = 350 x 10^6 / 146,132 A_s = 2,395 mm^2
Select bars: 5-25M bars (A_s = 5 x 500 = 2,500 mm^2 > 2,395 mm^2)
Check minimum reinforcement per CSA A23.3 Clause 10.5.1: A_s,min = 0.2 x sqrt(f'_c) x b x d / f_y = 0.2 x 5.48 x 350 x 500 / 400 = 480 mm^2 Also A_s,min = 1.4 x b x d / f_y = 1.4 x 350 x 500 / 400 = 613 mm^2
2,500 mm^2 > 613 mm^2 — OK
Check maximum spacing per CSA A23.3 Clause 10.6.1: Maximum clear spacing = min(3h, 450 mm) = min(1500, 450) = 450 mm Actual spacing = (350 - 2 x 40 cover - 2 x 10M stirrup - 25) / 4 = 59 mm — OK
Development length per Clause 12.2 (bottom bar, uncoated): L_d = 828 mm (as calculated above). Available embedment at support = 300 mm (typical seat width) — insufficient. Hooks or mechanical anchorage required at exterior supports.
Detailing Considerations
Per CSA A23.3:19 Clause 7.4, the following minimum concrete cover requirements apply for cast-in-place concrete:
| Exposure Condition | Cover (mm) |
|---|---|
| Cast against and permanently in contact with ground | 75 |
| Exposed to weather or in contact with ground (15M-55M bars) | 50 |
| Exposed to weather or in contact with ground (10M bars, wire) | 40 |
| Not exposed to weather — slabs, walls, joists (10M-20M) | 20 |
| Not exposed to weather — slabs, walls, joists (25M-55M) | 30 |
| Not exposed to weather — beams, columns | 40 |
Seismic Detailing Requirements
For ductile moment-resisting frames per CSA A23.3:19 Clause 21.3:
- Confinement reinforcement (hoops) must use seismic hooks (135-degree, 6d_b extension)
- Maximum hoop spacing in plastic hinge zones: d/4, 8 x d_bl (longitudinal bar diameter), or 200 mm
- Cross-ties must engage longitudinal bars at maximum 350 mm spacing
- Grade 500W may be used for longitudinal reinforcement; hoops are typically 10M Grade 400W
- Lap splices are not permitted in plastic hinge zones within 2 x member depth from the joint face
Design Resources
- Canadian Steel Grades
- Canadian Steel Properties
- CSA S16 Code Overview
- CSA S16 Beam Design
- Column Capacity Calculator
- Beam Capacity Calculator
- Canadian CSA Bolt Capacity
- All Canadian References
Frequently Asked Questions
What rebar sizes are used in Canada? Canada uses metric rebar sizes per CSA G30.18: 10M (11.3 mm diameter), 15M (16.0 mm), 20M (19.5 mm), 25M (25.2 mm), 30M (29.9 mm), 35M (35.7 mm), 45M (43.7 mm), and 55M (49.5 mm). The nominal cross-sectional areas range from 100 mm^2 (10M) to 2000 mm^2 (55M). The most commonly specified sizes for building construction are 15M (stirrups and light reinforcement), 20M and 25M (beam and slab flexural reinforcement), and 30M (heavy column and beam reinforcement). Bar sizes 45M and 55M are typically used only for large-diameter pile caps and heavily loaded transfer structures.
What are the standard rebar grades in Canada? CSA G30.18 specifies Grade 400W (f_y = 400 MPa, f_u = 540 MPa) and Grade 500W (f_y = 500 MPa, f_u = 620 MPa). Grade 400W is the standard grade for most reinforced concrete applications in Canada, corresponding approximately to ASTM A615 Gr. 60 but with weldability certification. Grade 500W provides 25% higher yield strength, making it economical for heavily loaded columns and beams where congestion is a concern. The "W" suffix indicates weldability, with a maximum carbon equivalent of 0.55% for 400W and 0.60% for 500W — an important distinction from standard ASTM grades.
How does CSA G30.18 compare to ASTM A615? CSA G30.18 Grade 400W is close to ASTM A615 Gr. 60 (f_y = 420 MPa vs. 400 MPa in Canada). The key differences are: (a) the "W" suffix guarantees weldability, while A615 Gr. 60 has no weldability requirement; (b) Canadian bars use metric sizing (10M-55M) vs. US imperial sizing (#3-#18); (c) the bar diameters are not always directly equivalent (e.g., 35M = 35.7 mm vs. US #10 = 32.3 mm); (d) CSA G30.18 requires bend and re-bend tests that are more stringent than ASTM A615; and (e) the elongation requirements differ slightly (12% vs. 10% in 200 mm gauge for 400W/A615 Gr. 60).
What is the development length for Canadian rebar? Per CSA A23.3:19 Clause 12.2, the basic tension development length is L_d = 0.45 x k_1 x k_2 x k_3 x k_4 x (f_y / sqrt(f'_c)) x d_b. The modification factors depend on bar location (top vs. bottom bars), coating, concrete density, and bar size. For a typical 25M bottom bar in 30 MPa concrete, the development length is approximately 830 mm. Lap splice lengths are typically 1.3 to 1.7 times the development length depending on the percentage of bars spliced at the same location and the stress level.
What seismic reinforcement requirements apply in Canadian concrete construction? CSA A23.3:19 Clause 21 provides seismic detailing requirements for ductile moment-resisting frames and ductile walls. Key requirements include: confinement reinforcement in plastic hinge zones with seismic hooks (135-degree, 6 x d_b extension), maximum hoop spacing of d/4 or 8 x longitudinal bar diameter or 200 mm (whichever is least), and no lap splices within 2 x member depth of the beam-column joint. The confinement reinforcement ratio must meet rho_s >= 0.45 x (A_g / A_ch - 1) x f'_c / f_yh for rectangular hoops. All hoops and cross-ties must be Grade 400W or 500W with the "W" weldability suffix, and cross-ties must engage longitudinal bars at a maximum spacing of 350 mm.
Educational reference only. Verify all values against the current edition of CSA G30.18-09 and CSA A23.3:19. This information does not constitute professional engineering advice. Always consult a qualified structural engineer.