[A] 105.3 Alternative Materials, Design and Methods
The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method shall be approved where the building official in concurrence with the fire chief finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, not less than the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety.
Where the alternative material, design or method is not approved, the building official shall respond in writing, stating the reasons why the alternative was not approved.