Objectives, functional statements and alternative solutions

Two weeks into the term, the engineer for Kingsway Tower sent a request to the building department. The owner wanted to use a pressure-rated drainage system of a newer plastic material for the high-rise stacks, partly to save weight and partly because the material was quieter than the original design. The material was certified to a product standard, but the plumbing code's list of permitted drainage materials did not include it for buildings of that height. Maya asked Luis how a building could use something the code did not list. "The code is a floor," he said, "not a fence. If you can prove something else is at least as good, there is a way to get it approved. It just takes work."

This lesson covers the part of the code that explains what the rules are for, and how a designer can meet the code another way. In Canada, the national codes and Ontario's code are objective-based: every technical rule is linked to objectives and functional statements, and a designer may propose an alternative solution that achieves the same level of performance.

Prescriptive rules and performance

Most of a plumbing code is prescriptive. It tells you exactly what to do: use this material, install this size, slope at this rate, put a cleanout here. Prescriptive rules are easy to follow and easy to inspect. Their weakness is that they cannot anticipate every situation or every new product. A rule written for cast iron and copper may not fit a material invented twenty years later.

Performance thinking starts from the other end. Instead of asking what the rule says, it asks what the rule is trying to achieve: keep sewer gas out, keep drinking water clean, prevent scalding, carry the flow without blockage. If a design achieves the goal at least as well as the prescribed solution, it should be acceptable. Modern plumbing codes combine the two approaches: prescriptive rules for ordinary work, and a route for proving that something different performs as well.

What the rules are for

Division A of the NPC and of Ontario's code sets out the code's objectives: broad goals that the requirements serve. For plumbing, the main objectives are safety, health and protection of the building from water and sewage damage. Under each objective are sub-objectives, such as limiting the probability that people will be exposed to an unacceptable risk of illness from contaminated water.

Division A also contains functional statements, which describe what a building or system must do to meet the objectives. A functional statement might say, in effect, that the system must convey waste to the sewer, or must limit the entry of contaminants into the potable water system. Each requirement in Division B is linked to one or more objectives and functional statements, and these links are published with the code. When you look up a requirement, you can also see why it exists.

Why intent matters on the job

Knowing what a rule is for helps a plumber in three ways. First, it helps in interpreting unclear wording: the reading that serves the rule's purpose is usually the right one. Second, it helps in explaining the rule to others, such as a foreman who wants to move a fixture or an owner who wants to skip a backflow preventer. Third, it helps in spotting when a prescribed solution does not work on a particular job and something else is needed.

Luis gave Maya an example. The code requires a cleanout at the base of each stack. A plumber who knows the purpose, which is to let someone rod a blockage at the point where it is most likely to form, will make sure the cleanout is accessible and faces the right way, not buried behind a finished wall where it technically exists but cannot be used. A plumber who only knows the rule may install it and still fail the purpose.

Alternatives: the route for something different

In Ontario, a building may comply with the code either by meeting the acceptable solutions in Division B or by using an alternative solution that achieves at least the minimum level of performance required by Division B in the areas defined by the objectives and functional statements attributed to the acceptable solution it replaces. In plain terms, an alternative must do the job at least as well as the rule it replaces, measured against the same objectives.

An alternative is not a loophole. The burden of proof is on the person proposing it, usually the design engineer, and the authority can say no. Typical evidence includes:

• Test results from an accredited laboratory showing that a product meets a recognized standard and performs as required.

An evaluation from a recognized evaluation body, such as the Canadian Construction Materials Centre, or in Ontario a ruling from the Minister or an authorization from the Building Materials Evaluation Commission.

• Engineering analysis comparing the alternative with the prescribed solution against each relevant objective or purpose.
• Evidence of successful use elsewhere, such as in other jurisdictions or in a newer edition of the code.

The alternative applies only to the project for which it was approved. Using the same product on the next building means asking again, unless the authority has issued a general approval or the product has been added to the code.

Kingsway's drainage material proposal

Maya followed the engineer's proposal for the stack material as it went through the building department, because Luis wanted her to see how it worked. The engineer's submission had five parts.

• A description of the proposal: which stacks, which floors, which material and joining method, and which code requirement it would replace.

The objectives and functional statements attributed to the requirement being replaced, taken from the published tables in Division A, so that the review compared like with like.

• Product evidence: the material's certification to its product standard, pressure and temperature ratings, and laboratory data on joint strength and fire performance.
• Fire safety: how the material would be fire stopped where it passed through floors, using a listed firestop system tested for that material and pipe size.
• Installation and inspection: the manufacturer's installation manual, training for the installers and a testing plan.

The building official asked two follow-up questions, one about noise and one about expansion in the tall stacks, and the engineer answered both. Six weeks later the alternative was accepted for Kingsway's stacks, with conditions: installers had to be trained by the manufacturer, every joint had to be inspected before the shafts were closed, and the firestop systems had to match the tested assemblies exactly. Northbridge kept the approval letter in the job file and gave copies to every crew working on the stacks.

Dealing with products that are new to you

Every year new products appear: new pipe materials, new joining systems, new valves, new fixtures. Some are covered by the code from the start, because they meet a standard the code already references. Others need an approval. A plumber on site cannot always tell which is which, so it pays to ask.

• Check the marking: which standard does the product say it meets, and is that standard referenced in the adopted code for this use?
• Check the code's permitted uses: a material may be allowed for drainage but not for water supply, or below ground but not above.
• Check the specification: is the product named or approved by the engineer?
• If in doubt, ask the engineer or the building official before installing it, not after.

Luis had seen a crew lose a week because a supplier sent a new type of mechanical coupling that looked like the specified one but was certified to a different standard. The inspector rejected it, and every coupling had to be replaced. The lesson was to check markings on delivery, not at inspection.

The program below is a simple decision helper based on that checklist. It is a learning tool, not a substitute for reading the code and asking the authority.

# A simple decision helper: is an approval needed before installing this product?
def needs_approval(meets_referenced_standard, permitted_for_this_use, in_spec_or_approved):
    if not meets_referenced_standard:
        return "Yes: no recognized standard - needs an approved alternative or must not be used"
    if not permitted_for_this_use:
        return "Yes: the code does not permit it for this use - needs an approved alternative"
    if not in_spec_or_approved:
        return "Ask the engineer: code-compliant, but not the specified product"
    return "No approval needed: install to the code and the manufacturer's instructions"

cases = {
    "PEX tubing with the referenced standard mark": (True, True, True),
    "new stack material, not listed for this use": (True, False, True),
    "coupling with an unknown standard": (False, True, False),
    "different brand of listed copper fitting": (True, True, False),
}
for name, args in cases.items():
    print(f"{name}:\n   {needs_approval(*args)}")

PEX tubing with the referenced standard mark:
   No approval needed: install to the code and the manufacturer's instructions
new stack material, not listed for this use:
   Yes: the code does not permit it for this use - needs an approved alternative
coupling with an unknown standard:
   Yes: no recognized standard - needs an approved alternative or must not be used
different brand of listed copper fitting:
   Ask the engineer: code-compliant, but not the specified product

Variances, rulings and appeals

Sometimes an owner and a building official disagree about whether a proposal meets the code. In Ontario, the Building Code Act provides routes for resolving these disputes. The Building Code Commission can hear disputes about whether a proposal achieves the code's requirements, and its decisions settle the question for that project. The Minister can also issue rulings authorizing the use of particular materials or systems across the province. These routes take time, so they are used for significant questions, not small details.

For an apprentice, the practical point is that the code is not fixed in stone for a given project. There are legal ways to approve something different. There are also legal limits: no route allows protection of health and safety to be reduced below the code's level.

When the code is silent

Occasionally a situation is not covered at all, such as an unusual fixture or a system the code never imagined. The code usually has a general provision for this, saying that work not specifically covered must be done in a way that meets the code's intent or objectives, to the satisfaction of the authority. In practice, that means the designer proposes a method based on recognized standards, the manufacturer's instructions and good practice, and the authority accepts it before the work goes in. Silence in the code is not permission to do anything at all.