How a bay is built

Clear height: what it means and why it decides everything

Clear height is the single most consequential dimension in an industrial bay. What it measures, where it is measured, and what each range of height allows.

Clear height is the unobstructed vertical distance from the finished floor to the lowest overhead obstruction across the usable area of the bay. It is not the height to the roof, and it is not the height at the peak.

The lowest obstruction is usually the bottom chord of a joist, but it can just as easily be a sprinkler pipe, a light fixture, a duct, a heater or the header over the overhead door. A building advertised at 24 feet can deliver 21 usable feet once the sprinkler mains and lights are in.

The dimensions people confuse

Term	What it measures
Clear height	Floor to the lowest overhead obstruction. The number that governs racking.
Ceiling height	Floor to a finished ceiling, if there is one. Usually only relevant in the office.
Eave height	Floor to the underside of the roof at the exterior wall. Always taller than clear height.
Peak height	Floor to the highest point of the roof. Marketing height, rarely useful.
Under-joist height	Floor to the bottom of the structural joist, before services are counted.

What each range gives you

Clear height	What it supports
Under 14 ft	Older stock. Ground storage and workshop use. Racking is limited to two levels at best.
14 – 17 ft	Two to three racking levels. Common in 1960s–1980s multi-tenant buildings.
18 – 22 ft	Three levels comfortably. The most common range in newer small-bay product.
24 – 28 ft	Four levels. Usually found in larger units and newer multi-tenant buildings.
30 ft and above	Distribution-grade. Rare in bays, normal in modern big-box industrial.

Measure it yourself, at the worst point

Take a laser measure to a viewing. Measure at the door, in the middle of the bay, under the sprinkler main and under the lights. The number that matters is the lowest one along the line where your racking will run — not the best number in the room, and not the number on the brochure.

Sprinklers set a ceiling on your storage, not just your racking

Even where the steel allows another level, the sprinkler design may not. Storage height, commodity class, packaging and rack configuration all feed into the fire protection design, and exceeding what the system was designed for is both an insurance problem and a code problem. Read sprinklers and fire protection before you plan a rack layout, and get the design confirmed in writing.

Questions

Frequently asked

Is clear height measured to the joist or to the sprinkler?

To whichever is lower over the area you intend to use. The honest way to quote it is to the lowest obstruction; the generous way is to the underside of the joist. Ask which convention the number you were given uses, and verify it on site.

How much clear height do I need for three levels of racking?

As a planning figure, around 18 to 20 feet is usually workable for three levels of standard pallet racking with clearance above the top load, but the real answer depends on pallet height, beam sizes, and the clearance the sprinkler design requires above the top of storage. Confirm it against the rack drawing and the fire protection design.

Does a mezzanine reduce clear height?

Under the mezzanine, yes — substantially, often to eight or nine feet. That area becomes storage or office, not racking. A mezzanine over the office at the front of a bay usually costs you nothing useful; one in the middle of the warehouse can cost you a great deal.

How a bay is built

Other guides

What an industrial bay actually is Industrial bay sizes, and what actually fits in them Power in an industrial bay Heating, ventilation and make-up air Sprinklers, fire protection and what you are allowed to store Zoning and permitted uses for industrial bays in Alberta

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