Mecklenburg County
Common Code Defects
Commercial- Building
Code Defects
• Draftstopping missing or not sealed properly in concealed floor
spaces of wood frame construction
Code Description
Section 717.3.2 & 717.3.3
Section 717.3.2 “Draftstopping shall be provided in floor/ceiling spaces in Group R-1 buildings,
in Group R-2 buildings as applicable in Section 101.2 with three or more dwelling units, in Group
R-3 buildings as applicable in Section 101.2 with two dwelling units and in Group R-4 buildings.
Draftstopping shall be located above and in line with the dwelling unit and sleeping unit
separations.
Exceptions:
1. Draftstopping is not required in buildings equipped throughout with an automatic sprinkler
system in accordance with Section 903.3.1.1.
2. Draftstopping is not required in buildings equipped throughout with an automatic sprinkler
system in accordance with Section 903.3.1.2, provided that automatic sprinklers are also
installed in the combustible concealed spaces”.
Section 717.3.3 “In other groups, draftstopping shall be installed so that horizontal floor areas
do not exceed 1,000 square feet (93 m2).
Exception: Draftstopping is not required in buildings equipped throughout with an
automatic sprinkler system in accordance with Section 903.3.1.1”.
Possible Options:
•
Draft stopping using approved material as listed in Section 717.3.1 which is ½
drywall, 0.375 inch wood structural panel, 0.375 inch particleboard or other
approved material shall be installed on floor systems, typically open web floor
trusses. The primary issue when installed has to do with its effectiveness.
Penetrations like floor truss bracing, water lines, electrical, hvac, etc…. Need to
be properly sealed. All holes and penetrations should have and approved
draftstopping material such as firecaulk, fiberglass or rockwool insulation,
expandable foams, etc… (used to restrict the movement of air in a floor
assembly) installed to effectively seal the required draftstop material.
Disclaimer: There may be other ways to comply with the Code. If so, you are not
required to use this method to comply with the Code. You may want to
investigate other options, or consult with a design professional identifying an
equally code compliant solution.