Appeal 11361
Appeal Summary
Status: Decision Rendered - Reconsideration of ID 11212
Appeal ID: 11361
Submission Date: 12/7/14 1:35 PM
Hearing Date: 12/10/14
Case #: B-010
Appeal Type: Building
Project Type: commercial
Building/Business Name: Clay Street Associates LLC
Appeal Involves: Erection of a new structure
Proposed use: Multi-Family Residential
Project Address: 1500-1520 SW 12th Ave
Appellant Name: Walter Currin
LUR or Permit Application #: Permit 14-170294-CO
Stories: 8 Occupancy: R-2 Construction Type: I-B
Fire Sprinklers: Yes - Fully sprinklered per NFPA 13
Plans Examiner/Inspector: Jody Orrison
Plan Submitted Option: pdf [File 1]
Payment Option: electronic
Appeal Information Sheet
Appeal item 1
| Code Section | 1207.2 AIR-BORUNE SOUND, 1207.3 STRUCTURE-BORUNE SOUND |
|---|---|
| Requires | 1207.2 - Walls, partitions and floor/ceiling assemblies separating dwelling units from each other or from public service areas shall have a sound transmission class (STC) of not less than 50 (45 if field tested) for air-borne noise when tested in accordance with ASTM E 90. 1207.3 – Floor/ceiling assemblies between dwelling units or between dwelling units and a public or service area within the structure shall have an impact insulation class (IIC) of not less than 50 (45 if field tested) when tested in accordance with ASTM E 492. |
| Code Modification or Alternate Requested | |
| Proposed Design | Proposed floor/ceiling assembly Type A would consist of: (2) layers type X gypsum board, 7/8 inch metal hat channel at 24-inches on center, 12-inch deep composite metal joist, topped with 3-1/2-inches of regular weight concrete and a finished floor. Type C floor/ceiling assembly is the same as Type A, except adds the following suspended from the ceiling: (1) layer type X gypsum board, suspended the assembly above with a concealed grid and 3-1/2 inches of acoustic batt insulation. |
| Reason for alternative | While the baseline assembly of UL G524 (3-1/2-inch concrete, min. 12 deep metal joist, 7/8-inch furring channel, and 1/2-inch type C GWB) achieves the required fire rating, it is projected that it would be acoustically inadequate to meet code minimums. The proposed assembly uses more GWB than the baseline assembly in order to control noise transmission—the proposed assembly uses (2) layers of 5/8” Type ‘X’ GWB rather than (1) layer of ½”Type ‘C’ GWB. By including a greater mass of GWB within the assembly, the assembly achieves the required acoustic performance, and provides equal or superior fire protection of the baseline assembly. |
Appeal Decision
Sound ratings per engineered analysis: Granted as proposed.
The Administrative Appeal Board finds that the information submitted by the appellant demonstrates that the approved modifications or alternate methods are consistent with the intent of the code; do not lessen health, safety, accessibility, life, fire safety or structural requirements; and that special conditions unique to this project make strict application of those code sections impractical.