Interpretation #7002
Published June 18, 2012
Original Request
- Code Version
- 2001
- Code
- MECHANIC
- Code Description
- Mechanical
- Chapter
- 6
- Section
- 601.4
- Topic
- 24
Question
Is it the intent of section 601.4 exeption 3 to mean if a house was permitted in 2003 it requires return air vents in all habital rooms including the master suite. Even if there is a return vent just outside the master bedroom door?
Answer Published 06/18/2012 at 1:53 PM
No; with a caveat. 601.4 of the Florida Building Code -
Mechanical (FBC-M) does not specifically require return air
registers to be installed in any location. This section
stipulates that the pressure differential be not more
than 0.01" W.C. This may be accomplished by a varied
amount of designs. The last sentence of Exception #3
states "...except that all supply air into the master suite
shall be included." In order to accomplish this it is
likely that a return air duct will be required especially
when it's a large master suite or other large habitable
room.
Mechanical (FBC-M) does not specifically require return air
registers to be installed in any location. This section
stipulates that the pressure differential be not more
than 0.01" W.C. This may be accomplished by a varied
amount of designs. The last sentence of Exception #3
states "...except that all supply air into the master suite
shall be included." In order to accomplish this it is
likely that a return air duct will be required especially
when it's a large master suite or other large habitable
room.
Commentary
One way to determine if the duct system is in compliance is
to hire a local air balance company to perform a test
report on the home. If the duct system is not in
compliance with exception #1 or #2, then a return air duct
would probably have to be installed, or some other design
provision to meet the 0.01" W.C. as required by FBC-M 601.4.