Fire Wall Construction in Phoenix, AZ

Frequently Asked Questions About Masonry Services

• What is a fire wall and how is it different from a fire partition?
  A fire wall is a structural wall designed to contain and limit the spread of fire between building sections or occupancies. A fire partition is a non-structural wall that creates a fire-rated separation but does not have independent structural requirements. Fire walls are more stringent: they must withstand a full fire test and maintain structural integrity during a fire event. Fire walls have ratings (2-hour, 3-hour, 4-hour); fire partitions are typically rated at 1 hour. City of Phoenix building code specifies which type is required based on occupancy and building size.
• What fire rating is required for commercial demising walls in Phoenix?
  The fire rating for commercial demising walls (walls separating tenant spaces) is typically 2 hours for office buildings under the International Building Code (IBC). Multi-use or mixed-occupancy buildings may require 3 or 4-hour ratings depending on the occupancies being separated. Parking structures have different requirements. The architect of record specifies the required rating on the structural drawings based on the building code occupancy classifications.
• What CMU block thickness is required for a 2-hour fire wall?
  The CMU block thickness for a 2-hour fire-rated wall depends on the specific UL-listed design referenced on the drawings. A common 2-hour fire wall assembly uses 8-inch CMU block, but 6-inch or 10-inch block may also be acceptable depending on the UL design. The UL design number on the structural drawings specifies the exact assembly including block size, mortar type, and grout fill. Father & Son Masonry follows the specific UL design on the plans — no variations are acceptable.
• Can penetrations be made through a fire wall?
  Yes, but they must be protected. Every pipe, duct, cable, or conduit passing through a fire wall must be sleeved and fire-stopped according to a UL-listed penetration detail. An unprotected penetration breaches the fire rating and makes the wall ineffective. Fire stopping materials include fire-rated caulk, intumescent sealants, or mechanical sleeves, depending on the penetration type and size. All penetrations are documented and inspected before walls are closed.
• What inspections are required for fire wall construction in Phoenix?
  Fire wall construction in Phoenix requires special inspection by a third-party building inspector retained by the building owner. The special inspector verifies that the assembly matches the UL design, checks block type and thickness, inspects mortar joints, verifies grout placement in lifts, and signs off on penetration sleeves and fire stopping before they are covered. City of Phoenix issues a final Certificate of Occupancy only after special inspection approval of fire walls.