Codes, permits and fire safety coordination

Every system in this course is governed by codes, and most of them need a permit and an inspection before they can be used. Kitchen exhaust is among the most heavily inspected work a sheet metal shop does, because grease duct fires spread through buildings, and combustible-dust systems are drawing more attention from fire officials every year. This lesson pulls the code material from the earlier lessons together: which documents apply in Nova Scotia, who enforces them, what the permit and inspection steps are, and how Keelson coordinates its work with the fire protection, electrical and building trades so the finished system passes the first time.

The code family

In Canada, the National Building Code and the National Fire Code are model codes that provinces adopt, sometimes with changes. Nova Scotia adopts the National Building Code through its building code regulations, and the National Fire Code through the Fire Safety Act and its regulations, with the Office of the Fire Marshal responsible for fire safety. Both national codes reference NFPA 96 for commercial cooking ventilation, and the referenced edition is the one named in the code edition being enforced, not necessarily the latest NFPA edition. Listed hoods are tested to CAN/ULC-S646 and factory-built grease ducts to CAN/ULC-S662; fire-resistance ratings of shafts come from the building code. For dust and fume systems, the fire code and the referenced NFPA standards set the hazard requirements, and the province's occupational health and safety regulations set exposure limits, with Nova Scotia using the ACGIH threshold limit values.

Codes change. A new edition of a model code or an NFPA standard does not apply on a job until the jurisdiction adopts it, so the first question on any project is which editions the authority having jurisdiction is enforcing. The second question is what the engineer's specification adds, because specifications often go beyond the code minimum, and the third is what the listing of each product requires, because a listed hood, duct or fan must be installed exactly as its listing says to keep that listing.

Permits and drawings

Kitchen exhaust and industrial exhaust systems normally need a mechanical or building permit, and often a separate fire department review of the suppression system. The permit application includes drawings showing the hood, the duct route, clearances, enclosures, the fan and the make-up air, with the listed product data. On Brine & Ember, Dev Bhatt's drawings and the hood manufacturer's submittal went in with the permit; Keelson's shop drawings showing the exact duct route, cleanout locations and shaft penetrations went to Dev for review first. The suppression contractor submitted their own drawings to the fire authority. Because the hood listing, the suppression design and the duct must all agree, a change to one, such as moving an appliance under the hood, must be checked against the others.

For Ironbark, the dust collection system was designed by Tomasz Wrona with a dust hazard analysis, the explosion protection design and the collector's vent calculations supporting the permit. The authority asked for the vent discharge area to be shown on the site plan, so that no one would park or walk in the vent's discharge zone, and for the isolation devices to be shown on the ductwork drawings.

Inspections during construction

Grease duct work is usually inspected before it is concealed. The inspector wants to see the welds, the slope, the cleanouts and their access, the clearances, and in some jurisdictions a leakage test. The traditional test is a light test, in which a strong lamp is passed through the duct and the inspector looks for light escaping at joints; some jurisdictions accept or require a pressure test instead. The shaft enclosure is inspected separately, including the fire-rated access doors at cleanouts. Only after the duct passes may it be enclosed or wrapped, and a duct that is closed in before inspection may have to be opened again at the contractor's cost.

For dust and fume systems, inspections focus on the collector location and its vents, the isolation devices, bonding and grounding, and the duct construction. Electrical inspectors look at equipment in classified areas. The fire authority may witness the commissioning of interlocks, such as the collector shutting down the fan and closing the isolation valve when a spark is detected.

Clearance and enclosure checks

Keelson's site leads carry a simple checklist for grease duct clearance and enclosure. The rules come from NFPA 96 and the code as adopted: 457 mm (18 in) to combustible construction, 76 mm (3 in) to limited-combustible construction and zero to noncombustible construction, unless a listed reduced-clearance method or a listed field-applied enclosure is used. Ducts passing through floors or into concealed spaces need a fire-rated enclosure, 1 h in buildings under four storeys and 2 h in buildings of four or more, with a clearance inside the enclosure. A short program can apply the rules to a survey of the route so nothing is missed.

# Grease duct clearance and enclosure checklist for a surveyed route
storeys = 4
need_rating = 2 if storeys >= 4 else 1
rules = {"combustible": 457, "limited": 76, "noncombustible": 0}
route = [("ceiling joist", "combustible", 480), ("steel beam", "noncombustible", 0),
         ("gypsum shaft wall", "limited", 150), ("wood blocking", "combustible", 300)]
for name, kind, gap in route:
    need = rules[kind]
    status = "ok" if gap >= need else f"short by {need - gap} mm"
    print(f"{name:18s} {kind:15s} gap {gap:>3} mm need {need:>3} mm  {status}")
print(f"shaft enclosure needed: {need_rating} h rating")

ceiling joist      combustible     gap 480 mm need 457 mm  ok
steel beam         noncombustible  gap   0 mm need   0 mm  ok
gypsum shaft wall  limited         gap 150 mm need  76 mm  ok
wood blocking      combustible     gap 300 mm need 457 mm  short by 157 mm
shaft enclosure needed: 2 h rating

The program flags the wood blocking, which a framer added after the duct was laid out. The fix is to remove the blocking or apply a listed reduced-clearance method; it is far cheaper to find on the survey than at the inspection. Kai now runs the same survey on every grease duct before calling for the rough inspection.

Coordinating with other trades

Exhaust systems involve many trades, and many failed inspections come from gaps between them. The suppression contractor needs the hood and duct in place to install nozzles and detection, and needs Keelson to provide the openings and supports their piping requires. The electrician wires the exhaust fan, the make-up air unit, the interlocks that shut off the cooking fuel and power on suppression discharge, and, for dust systems, the spark detection and isolation controls. The plumber or gas fitter installs the gas shutoff valve. The general contractor or the drywall trade builds the rated shaft and installs the access doors at Keelson's cleanouts. The roofer flashes the curb. Keelson's site lead keeps a coordination list of these handoffs so each trade knows when its part is needed.

Final inspection and approval to operate

Before Brine & Ember could open, the fire authority witnessed the suppression system's acceptance test, the TAB group's report confirmed the hood was exhausting its listed rate and the make-up air was balanced, and the building official inspected the finished installation. The owner received the operating and maintenance manuals, the suppression system's service schedule, and the cleaning schedule required by NFPA 96 for the kitchen's volume. Keelson's closeout package included the shop drawings, the weld and test records, and photographs of the duct before it was enclosed, which have saved more than one argument with a later inspector.

For existing systems, the fire authority enforces the inspection, cleaning and maintenance requirements. A restaurant whose hood and duct are not cleaned on schedule, or whose suppression system is out of service, can be ordered to stop cooking. Keelson is sometimes called in after such an order to replace damaged duct, add cleanouts or fix a fan that cannot be safely opened for cleaning.

When codes and specifications disagree

Sometimes the engineer's specification, the product listing and the adopted code do not say the same thing. The usual rule is that the most restrictive requirement governs, and that the listing must be followed for a listed product to keep its approval. If a specification calls for a lighter duct than the code allows, or shows a clearance smaller than the listing permits, Keelson does not choose for itself; the site lead writes a request for information to the engineer, who either confirms the stricter requirement or provides an approved alternative. A short written question at the shop drawing stage costs almost nothing, while a duct installed to the wrong rule may have to be removed after the inspection.

Alternative solutions are another route. Both the Canadian and the US codes allow a designer to propose a different way of meeting the code's intent, supported by tests, listings or engineering analysis, and the authority may accept it. Listed reduced-clearance systems, listed field-applied grease duct enclosures and factory-built grease ducts are the most common examples in kitchen work. They are approved through their listings rather than case by case, but the installer must follow every detail of the listing, from the number of wrap layers to the overlap at the seams and the firestopping at the floor.

Existing buildings bring their own questions. When a restaurant moves into an older building, the authority usually requires the new kitchen exhaust to meet current code, even if the building around it does not. A shaft built decades ago may lack the rating, the clearance inside it or the access doors a new grease duct needs, and the fix is often a listed wrap or a factory-built duct inside the old shaft. Keelson's site lead surveys the existing conditions before pricing, because what is behind the old walls decides the cost of the job.

Inspectors are part of the team, not opponents. Calling for an inspection when the work is genuinely ready, having the drawings, listings and test records on site, and walking the route with the inspector all make the visit shorter and the result more predictable. Kai has learned that a failed inspection is rarely about workmanship alone; more often it is a missing record or a question nobody asked in time.