What is damperin construction?

A fire damper closes mechanically, usually on a fusible link that melts at a set temperature, to keep fire from passing through a duct penetration in a rated wall or floor. A smoke damper closes on a signal from a smoke detector or the fire alarm system and needs an actuator and wiring. Combination fire/smoke dampers do both jobs in one body. They are priced very differently, so the takeoff has to keep the types separate.

Typical commercial specs call for a manual balancing damper in each branch duct, located near the takeoff from the main rather than right behind the diffuser, where a throttled damper generates noise in the occupied space. The TAB contractor uses them to proportion airflow to the design cfm at each outlet. Estimators usually carry one balancing damper per branch takeoff and then verify against the spec section and the drawing details.

Yes. Mechanical codes and NFPA standards require access to every fire and smoke damper for inspection, testing, and fusible link replacement, which in practice means a duct access door at each damper plus a ceiling access panel where the ceiling is not lay-in tile. Estimators should count access doors alongside the damper count, because a missed access door line across a full floor of fire dampers is a real dollar gap and a guaranteed inspection comment.