Clear height and ESFR: what you're buying.

Clear height is not ceiling height

Clear height measures floor to the lowest thing hanging down: sprinkler heads, joists, light fittings, ducting. The roof might be three feet higher. That gap is not yours.

It also is not the height you can rack to. Fire code requires clearance between the top of your stored product and the sprinkler heads. So the working number is lower again, and a building quoting a roof height rather than a clear height is quoting you something you cannot use.

Ask for clear height, then ask what the maximum permitted storage height is for your commodity class. Those are two different numbers and only the second one is yours.

What ESFR changes

A standard sprinkler system fights a fire from above, which works until stored product is high enough and dense enough that water cannot reach the seat of it. At that point the building's rating limits what you may store and how high.

Early Suppression Fast Response sprinklers respond faster and deliver a heavier, more focused discharge, suppressing the fire at its source rather than containing it. Both systems are safe. What ESFR changes is permission: an ESFR building may store more commodity classes, and store them higher.

• More of your product fits inside the same footprint, so you rent less floor for the same volume
• Commodity classes a standard system has to refuse become storable, which matters for plastics, packaging and many consumer goods
• High-pile storage (broadly, product stacked above around twelve feet) becomes possible at all

When cube beats floor

If your product is dense, uniform and stacks well, you are buying volume rather than area, and a building with height will hold your pallet count in a smaller footprint. If a provider is quoting you per square foot on product that stacks four high, you are paying for floor you are not using.

The reverse is also true and worth being honest about. Light, bulky, awkward product that cannot be stacked gains very little from clear height, and you should not pay a premium for it.

The four questions worth asking any building

These separate a specification that sounds impressive from one that will hold your product.

• What is the clear height, and what is the maximum permitted storage height for my commodity class?
• Is the sprinkler system ESFR, and is the building rated for high-pile storage?
• What is the column grid? Widely spaced columns mean fewer obstructions and better rack layout, particularly for long product
• What is the floor's load rating, and does the racking already installed suit my pallet dimensions?