Page: Last modified: 2023-11-20
Code Reference(s):
NPC20 Div.B (first printing)
Support for Nominally Horizontal Piping
This proposed change introduces horizontal spacing of supports for solid wall PVC plastic pipe.
This change could potentially affect the following topic areas:


The current 1.2 m pipe support spacing in Table of Division B of the National Plumbing Code of Canada (NPC) applies to all PVC pipe sizes. There is currently no differentiation for larger diameter pipes, which can be adequately supported by increased spacing. The use of supports at closer spacings than needed results in unnecessary additional costs and time for installation.

Cellular core PVC pipe was included as a pipe material option in the NPC 2020, but has not been included in Table As such, there is currently no required pipe support spacing for this material, which could lead to inadequate support. This situation can lead to stress on the pipe and sagging, which can lead to degradation and breakdown.

Larger diameter PVC pipe and cellular core PVC pipe are increasingly used by the industry; therefore, the spacing requirements should be revised to state proper support spacing for these products based on a water-filled product at maximum temperature.


This proposed change adds a new row to Table to incorporate different pipe sizes and corresponding pipe support spacing for solid wall PVC pipe. The clarity provided in directly linking support spacing to pipe size will allow the cost-effective installation of pipe supports, avoiding unnecessary costs.

This proposed change also adds cellular core PVC to the list of materials requiring a pipe support spacing of 1.2 m. This would help prevent the improper installation of pipe supports for this product, which mitigates the risk of pipe damage and degradation. Furthermore, this proposed change aligns Table with Article by including cellular core PVC pipe.


[] for Horizontal Piping

[1] 1)Nominally horizontal piping that is inside a building shall be braced to prevent swaying and buckling and to control the effects of thrust.
[2] 2)Nominally horizontal piping shall be supported as stated in Table
[3] 3)Where PVC, CPVC or ABS plastic pipe is installed,
[a] a)the pipe shall be aligned without added strain on the piping,
[b] b)the pipe shall not be bent or pulled into position after being welded, and
[c] c)hangers shall not compress, cut or abrade the pipe.
[4] 4)Where PEX, PE-RT, PP-R, PE/AL/PE or PEX/AL/PEX plastic pipe or tube is installed, hangers shall not compress, cut or abrade the pipe.
Table []
Support for Nominally Horizontal Piping
Forming Part of Sentence [][2] 2)
Piping Material Maximum Horizontal Spacing of Supports, m Additional Support Conditions
ABS, solid wall ABS or cellular core PVC plastic pipe 1.2
At the end of branches or fixture drains and at changes in direction and elevation
Solid wall PVC pipe
• diameter NPS 4 
At the end of branches or fixture drains and at changes in direction and elevation
• diameter ≥ NPS 4 and NPS 12
• diameter ≥ NPS 12
ABS or PVC plastic trap arm or fixture drain pipe > 1 m long
As close as possible to the trap
Cast-iron pipe 3.0 At or adjacent to each hub or joint
Cast-iron pipe with mechanical joints that is ≤ 300 mm long between adjacent fittings 1.0 None
Copper tube or copper and brass pipe, hard temper
• diameter NPS 1 
3.0 None
• diameter ≤ NPS 1 
Copper tube, soft temper 2.5 None
CPVC pipe 1.0 None
Galvanized iron or steel pipe
• diameter ≥ NPS 6 
3.75 None
• diameter NPS 6 
Lead pipe Throughout length of pipe None
PE/AL/PE composite pipe 1.0 None
PEX/AL/PEX composite pipe 1.0 None
PEX plastic pipe 0.8 None
PE-RT tube 0.8 None
PP-R plastic pipe 1.0
At the end of branches and at changes in direction and elevation
Stainless steel pipe
• diameter ≥ NPS 1 
3.0 None
• diameter NPS 1 
Stainless steel tube
• diameter ≥ NPS 1 
3.0 None
• diameter NPS 1 
[5] 5)Where hangers are used to support nominally horizontal piping, the hangers shall be
[a] a)supported by metal rods of not less than
[i] i)6 mm diam to support piping of NPS 2 or less,
[ii] ii)8 mm diam to support piping of NPS 4 or less, and
[iii] iii)13 mm diam to support piping over NPS 4, or
[b] b)solid or perforated metal straps not less than
[i] i)0.6 mm thick and 12 mm wide to support piping of NPS 2 or less, and
[ii] ii)0.8 mm thick and 18 mm wide to support piping of NPS 4 or less.
[6] 6)Where a hanger is attached to concrete or masonry, it shall be fastened by metal or expansion-type plugs that are inserted or built into the concrete or masonry.

Impact analysis

There are no additional costs associated with this proposed change, which enables construction efficiency and permits PVC piping to be supported at increased levels while maintaining functionality.

This proposed change also provides clarity regarding the spacing of supports for cellular core PVC pipe, which is required at a spacing already used in the Code, so no additional cost is expected to support this product.

Enforcement implications

No additional resources are needed for the enforcement of this proposed change.

Who is affected

Designers, installers, suppliers, regulators and building owners.


[] ([1] 1) [F20-OS3.1]
[] ([1] 1) [F20-OH2.1,OH2.3]
[] ([1] 1) [F20-OP5]
[] ([2] 2) [F20-OS3.1]
[] ([2] 2) [F20-OH2.1]
[] ([2] 2) [F20-OP5]
[] ([3] 3) [F20-OP5]
[] ([3] 3) [F20,F81-OS3.1]
[] ([3] 3) [F20-OH2.1]
[] ([4] 4) [F81-OP5]
[] ([4] 4) [F81-OS3.1]
[] ([5] 5) [F20,F21-OP5]
[] ([5] 5) [F20-OS3.1]
[] ([5] 5) [F20-OH2.1]
[] ([6] 6) [F20-OP5]
[] ([6] 6) [F20-OS3.1]
[] ([6] 6) [F20-OH2.1]
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