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Interpretation #5744

Original Request

  • Date: June 10, 2008
  • Requested By: Winford Lindsay
  • Requester E-Mail: blindsay@lpbatlanta.com
  • Code Version: 2004
  • Code: BUILDING
  • Code Description: Building
  • Chapter: 10
  • Section: 1016.4
  • Topic: Toilet room exhaust make up air

  • Question: Is it the intent of the referenced section to allow make- up air (in greater amounts than being exhausted) from passing from a corridor under a hotel guest room door into the hotel guest room, from where it is transferred into the toilet room under the toilet door, to make-up the toilet exhaust? Comment: Florida Building Code - Mech Section 601.2 appears to be the same as FBC - Building, Section 1016.4, and appears to be the same as the International Code - Mechanical, Section 601.2. The commentary for the IMC, Section 601.2 states, "The first exception addresses the common practice of using air from the corridor as make- up air for small exhaust fans in adjacent rooms. When the corridor is supplied directly with outdoor air at a rate greater than the exhaust rate, positive pressure will be created in the corridor with respect to the adjoining rooms, and smoke would not be drawn into the corridor". ASHRAE Intepretation IC-62- 1989-28 (April 26, 1998) supports this concept: Question - Can outdoor air requirements for a hotel bathroom be met by exhausting the bathroom at rate of at least 35 cfm with make-up air by transfer from the adjacent guestroom rather than direct supply of outside air to the bathroom. Their Answer - Yes.

Answer on 06/10/2008 at 11:54 AM

No. FBC-Mechanical Section 1016.4 allows for make up air
to rooms that open directly to the corridor, not thru the
adjoining room to another room. There may be other
sections of the code that apply depending on occupany or
load.

Commentary:

From the Florida Building Code Commentary; "It is not the intent of this section to prohibit the air movement necessary for ventilation and space conditioning of exit access corridors, but rather to prevent those spaces from serving as conduits for the distribution of air to or the collection of air from, adjacent spaces." In conclusion, an air distribution system for a corridor can serve supply and return only to the corridor itself, if an additonal space is being served by the same air distribution system it would have to have a direct ducted return and supply to the unit.