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Plumbing

Chase

In Plain English

A hidden vertical space inside a wall that pipes and ducts run through between floors of a building.

Definition

A vertical shaft or enclosed space built into a wall or structure to conceal and route pipes, ducts, or wiring between floors. Plumbing chases are typically located at wet wall locations and sized to accommodate stacks, supply lines, and vent pipes. Proper fire-stopping is required where chases penetrate floor and ceiling assemblies.

Why It Matters in Bidding

Chases concentrate plumbing, mechanical, and electrical runs into shared vertical paths, so coordinating them affects multiple subs' scopes and the building's usable floor area, both of which feed pricing decisions. During takeoff, estimators must account for chase framing, access panels, and code-required fire-stopping at every floor penetration, because missed fire-stopping is a common inspection failure that can delay the CO.

Example

Reviewing the plumbing riser diagram during takeoff, an estimator confirms the wet-wall chase is wide enough to stack the soil, vent, and supply lines, then adds firestop assemblies at each floor penetration to the mechanical sub's scope.

Related Terms

Vent StackDrain-Waste-Vent (DWV)Rough-InSoil Pipe

Frequently Asked Questions

The terms overlap, but a chase usually refers to a smaller concealed space within a wall for routing pipes, ducts, or wiring, while a shaft is a larger, often fire-rated enclosure running the full building height for elevators, stairs, or major mechanical risers. Both require proper fire-stopping at penetrations.
Where pipes penetrate rated floor and ceiling assemblies, the openings must be sealed with listed firestop systems to maintain the assembly's fire rating and stop smoke and flame spread between floors. Inspectors check these closely, and missing or incorrect firestop is a frequent cause of failed inspections and CO delays.
Chase framing is usually the carpentry or drywall scope, but the size and location depend on the plumbing and mechanical layouts. Estimators should confirm the contract clarifies who frames, who provides access panels, and who installs fire-stopping, since these items frequently fall into scope gaps between trades.

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