In Plain English
Quick Answer
A self-contained heating and cooling unit mounted on the roof that connects to the building's ductwork below.
Definition
Definition
A packaged HVAC unit installed on the roof of a building that provides heating, cooling, and ventilation through an internal duct distribution system. Rooftop units (RTUs) are among the most common HVAC systems for low-rise commercial buildings due to their low first cost, simple installation, and easy rooftop service access. They may be single-zone or multi-zone and may include gas heat, electric heat, or heat pump heating.
Context
Why It Matters in Bidding
RTUs are frequently the largest single line item on a commercial HVAC bid, and their long lead times make them a scheduling and cash-flow risk an estimator must flag. Beyond the unit price, the bid must capture roof curbs, structural support, crane/rigging, gas and electrical connections, and controls integration, which are easy to overlook when pricing only the equipment.
Example
Example
A mechanical estimator pricing a strip-mall buildout carries five 5-ton packaged RTUs plus roof curbs, a one-day crane rental for set, and the associated gas, electrical, and economizer controls in the bid.
See Also
Related Terms
FAQ
Questions Contractors Ask
What costs beyond the unit should an RTU bid include?
Carry roof curbs or rails, structural curb adapters, crane and rigging for the lift, ductwork transitions, gas piping, electrical disconnects and feeders, condensate, and controls or building-automation integration. Roofing patch-in around the curb may belong to another trade, so clarify scope splits to avoid gaps or double-counting.
Why do RTU lead times matter for a bid?
Packaged units, especially larger tonnages or units with special options, can carry long manufacturer lead times that affect the project schedule and your procurement cash flow. Estimators should note lead times in the proposal, lock pricing where possible, and account for potential escalation or substitution if the awarded schedule slips.
How is RTU tonnage estimated for a bid?
Tonnage comes from the engineer's load calculation or equipment schedule, not from rules of thumb at bid time. Estimators bid the units and capacities shown on the mechanical schedule and drawings. If you must value-engineer, propose an alternate that meets the specified capacity and efficiency rather than guessing at size.
Need more than definitions?
Get AI-powered bid alerts, automated form filling, and proposal drafting.
Start Free Trial