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Heat or Smoke at the Top of an Elevator Shaft? Why the Correct Answer Depends on the Design

July 22, 2026

A recent Canadian fire alarm discussion asked a question that sounds simple:

What type of detector is usually installed at the top of an elevator shaft—heat or smoke?

The careful answer is: it depends.

In the Ontario code language checked for this article, certain elevator-hoistway conditions call for a fire detector. That term includes both heat detectors and smoke detectors. CAN/ULC-S524 then tells us where a required shaft detector is installed, but it does not reduce every elevator-shaft design to one universal device type.

The final choice depends on the applicable code path, sprinkler protection, elevator and fire alarm sequence, environmental conditions, accessibility, manufacturer requirements, and the approved design documents.

“Fire detector” does not mean only heat or only smoke

Ontario’s Building Code defines a fire detector as a device that detects a fire condition and automatically initiates an electrical signal. The definition includes both:

That distinction matters because Ontario Building Code Article 3.2.4.10. uses the broader term fire detector when addressing certain elevator hoistways.

It does not simply say, “Install a heat detector at the top of every elevator shaft.”

When Ontario’s Building Code calls for hoistway detection

Under OBC Article 3.2.4.10., where a fire alarm system is required in a building that is not sprinklered, fire detectors are required in certain spaces, including elevator hoistways and dumbwaiter shafts.

The same article also connects that requirement to sprinkler protection. The hoistway fire detectors described in the article are required where a sprinkler system is not installed within the hoistway or shaft.

That gives us the first important questions:

Without those answers, “heat or smoke?” starts too late in the conversation.

Where does S524 say to install it?

Once a fire detector is required in an elevator shaft, CAN/ULC-S524:2019 provides a clear location rule.

Clause 28.14.1 says a fire detector required in a shaft by the building code is mounted at the highest point of the shaft.

That tells us the required location. It does not, by itself, select heat instead of smoke.

The detector type still has to match the governing requirement, the fire alarm and elevator sequence, and the conditions at the top of the shaft.

Why heat detection is common—but not a universal rule

Heat detection is commonly encountered in elevator-hoistway applications. That may be appropriate where:

But common practice is not the same thing as a universal code requirement.

Saying “it is always a heat detector” skips the code wording and the building-specific design work.

Where smoke detection is specifically required

Smoke detectors are specifically required in several elevator-related locations and functions—but those should not be confused with a top-of-hoistway detector.

For example, the Ontario Building Code calls for smoke detectors in:

Those smoke detectors can be part of the elevator recall sequence. They serve a different purpose and location than a fire detector installed at the highest point of the hoistway.

A building may therefore have:

They are related, but they are not interchangeable.

Sprinklers and waterflow can change the answer

Sprinkler protection is another reason the question cannot be answered from a photograph of the shaft ceiling.

Ontario’s Building Code connects the hoistway fire-detector requirement to whether sprinkler protection is installed within the shaft. Where sprinklers are present, waterflow detection and fire alarm annunciation can become part of the life-safety arrangement.

CAN/ULC-S524 requires suppression-system activation to be annunciated at the building fire alarm system, and it includes requirements for waterflow-device operation.

That does not mean sprinklers automatically eliminate every elevator-related fire alarm requirement. It means the designer must consider the complete arrangement:

One system function cannot be evaluated in isolation from the others.

The shaft environment matters

The top of an elevator shaft can be a difficult detector location.

Depending on the building, it may involve:

CAN/ULC-S524 requires fire detectors to be accessible for periodic maintenance and testing. It also requires detectors to be suitable for the environmental conditions where they are installed.

Unless specifically designed for those conditions, detectors are not intended for locations outside the standard’s stated temperature, humidity, and airflow limits. Areas involving condensation, steam, corrosion, or high air movement require equipment suitable for those conditions.

That can affect whether a conventional spot smoke detector, heat detector, linear detector, aspirating system, beam detector, or another approved method is appropriate.

The correct detector is not simply the one that fits on the bracket.

Do not confuse the top of the shaft with the pit

CAN/ULC-S524 separately addresses heat detection at the bottom of an elevator shaft or pit.

Clause 28.14.2 describes the mounting of heat detectors installed in the pit. Clause 28.14.3 permits linear heat detection cable in place of spot heat detection for that pit application under the stated arrangement.

Those clauses should not be used to claim that the detector at the top of every shaft must also be heat detection.

Top-of-shaft and pit detection are separate design questions.

Elevator integration is more than detector placement

The detector is only one input in a larger life-safety sequence.

Depending on the building, fire alarm inputs may be associated with:

CAN/ULC-S536 expects the system documentation to describe the sequence of operation, ancillary equipment, and programmed input-to-output functions. Inspection and testing should confirm the installed system as designed—not merely confirm that one detector creates an alarm at the panel.

Detailed elevator shutdown or power-control requirements may involve ASME A17.1/CSA B44, elevator-controller design, and coordination with the elevator contractor and AHJ. Those requirements should not be invented from a general fire alarm rule.

What owners and property managers should ask

If your building has detection in or around an elevator shaft, ask:

“Heat or smoke?” is useful—but it should not be the only question.

What designers and technicians should check

Before selecting, replacing, or testing a detector at the top of an elevator shaft:

  1. Confirm the applicable Building Code or Fire Code path.
  2. Determine whether the requirement says fire detector, heat detector, or smoke detector.
  3. Confirm whether sprinkler protection is installed in the shaft.
  4. Review the fire alarm zoning, device list, verification report, and sequence of operation.
  5. Identify any elevator recall, sprinkler, smoke-control, or ancillary functions associated with the device.
  6. Check the shaft environment against the detector’s listed operating conditions.
  7. Confirm safe access for inspection, testing, and maintenance.
  8. Apply the correct CAN/ULC-S524 installation requirements and manufacturer instructions.
  9. Coordinate changes with the fire alarm designer, elevator contractor, sprinkler contractor, and AHJ where required.

Do not replace a heat detector with smoke—or smoke with heat—simply because one seems more common.

The real takeaway

There is no reliable one-word answer for every elevator shaft.

Ontario code language may require a fire detector at the top of an elevator hoistway under specific conditions. A fire detector may be heat or smoke. CAN/ULC-S524 requires a detector that is required in the shaft to be installed at the highest point, but the approved design determines which type belongs there.

The right answer depends on the code path, sprinkler protection, elevator functions, shaft environment, accessibility, and approved sequence—not on what someone usually sees in the field.

References

The applicable code edition, approved design documents, manufacturer instructions, elevator requirements, and AHJ direction must be confirmed for the specific building.

Working with Canadian fire and building codes? Ask Codebook Carl — answers are sourced directly from the code books with exact clause citations.