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Fireblocking and draftstopping are typically inspected at the time of the insulation inspection and should be complete at that time.

Fireblocking

Fireblocking, as the name implies, is intended to block the spread of fire from one concealed space to another. Fireblocking is required in a variety of places. In the average home, the two areas where fireblocking is most likely going to be required are:

  • At openings around wires, vents, pipes, and ducts where those items penetrate a top or bottom wall plate.
  • At the interconnection between wall and ceiling spaces. Most likely this will happen at kitchen soffits and dropped ceilings.

There are a number of ways to comply with fireblocking requirements for wire, vent, pipe and duct penetrations.

  1. There are caulks on the market for sealing the annular opening around wires, vents, pipes, and ducts. Some caulks are listed as "noncombustible". Others may also be "noncombustible" and "intumescent". Either product is acceptable. They should be installed in accordance with the manufacturers instructions.
  2. Unfaced fiberglass batts may be used as fireblocking provided that the batt is at least 16 inches in height measured vertically and fills the full width of the stud space. Insulation should be packed around the penetrating opening including the opening in the top or bottom plate. If the wire, pipe, vent or duct penetrates both the top and bottom wall plate, a 16" bat must be placed at both the top and bottom of the cavity, or the entire cavity may be filled.

Fireblocking the interconnection of wall to ceiling spaces can be more confusing. If there is a pathway for air to move from a stud space to a joist space, the path must be fireblocked. In these cases, the use of 1/2" gypsum board, 2" nominal lumber, 3/4" plywood or particleboard, or two thicknesses of 1 inch nominal lumber may be used. Fiberglass batts may also be used and is the most common way to fireblock soffits at exterior walls.

Draftstopping

Draftstopping is only required in floor/ceiling assemblies. Draftstops are not required in residential attics. Draftstops must be provided in floor systems whenever a concealed space occurs that exceeds 1000 square feet.

The two most common designs where this will occur are when open web trusses or dropped ceilings are used.

When draftstopping is required, the concealed space must be divided into roughly equal spaces by a draftstop. Using one of the floor trusses is one of the most practical locations for placement of a draftstop. Draftstops can be made of 1/2" gypsum board or 3/8" particleboard or plywood. Insulating foam can be used to seal abutting surfaces such as the intersection of the draftstop and a duct or pipe.

For more information, contact at 952-548-6320.