Floors, columns and structure inside a bay

The slab and the frame decide what you can install, where you can install it, and whether you can rack at all. Neither is easy to change, and neither appears in any public record.

The slab

An industrial floor is normally a concrete slab on grade. What matters is not just thickness but the sub-base under it, the joint layout and the condition. A thin slab on a poor base will fail under rack posts long before a thick one on a good base.

• Point loads are the concern with racking. A loaded rack concentrates its weight onto small base plates, and that is a very different demand from a uniformly distributed load.
• Uniform load capacity matters for bulk storage on the floor.
• Joints and cracks tell you a lot. Wide cracks, faulted joints and spalling at the door are signs of base movement or overloading.
• Anchoring — check the lease before you drill. Anchoring racking, machinery or a mezzanine into the slab is usually a landlord-consent item and often needs to be removed at the end of the term.

If you are installing racking, have the rack supplier confirm the loads and get the landlord to confirm the slab design. Do not infer capacity from the fact that the last tenant racked it.

Columns

Columns are where the structural bay meets your floor plan. In a small bay you may have none, because the unit sits within a single structural module. In a wider unit, one or two columns can land exactly where you wanted an aisle.

Sketch your rack runs and vehicle paths on a plan with the columns marked before you commit. A column in the middle of a 30-foot-wide bay is not fatal, but it changes the aisle layout and it will be in the way of a forklift turning circle for the whole term.

Demising walls

The wall between you and the next bay is a fire separation, and in most multi-tenant industrial buildings it runs to the underside of the deck. It carries a fire-resistance rating set by the building code for the construction and occupancy, and anything you attach to it or cut through it engages that rating.

Running a conduit, a duct or a doorway through a demising wall means restoring the separation properly — with a rated assembly, a fire damper or a certified penetration seal. This is inspected, and it is a common source of deficiency at the end of a term.

Drains, sumps and floor penetrations

Floor drains in industrial space are regulated, because what goes down them reaches the municipal system. A bay with a drain may have a sump, an interceptor or an oil–grit separator, and the tenant is usually responsible for its maintenance and for what is discharged.

If your process produces anything other than clean water, confirm what the discharge approval allows before you sign. Vehicle washing, food production, plating and paint operations all have specific requirements, and retrofitting an interceptor into a finished bay is expensive.

What to look at on site

• Walk the whole slab and look at the joints, especially where forklifts cross them.
• Look at the base of the walls for signs of water ingress.
• Find the drains, lift a grate if you are allowed, and ask what serves them.
• Note every column, its size, and where it sits relative to the door.
• Look up at the deck for previous penetrations, patched openings and abandoned services.