How to Fire block walls?
First, lets qualify the term "Fire Blocking" vs. "Draft
Stopping" Fire blocking is a term commonly used to describe the
blocking used at the mid span of a wood framed area to inhibit the
advance of fire within a concealed space, thereby maintaining the
structural integrity of the building during a fire. It is described
in the building codes (IRC/IBC) as follows: FIREBLOCKING. Building
materials installed to resist the free passage of flame to other
areas of the building through concealed spaces. Fireblocking is
seldom required in residential construction any more (there are
some exceptions), however there is a process called "Draft
Stopping" that is common in all wood framing and used extensively
in residential construction. Fireblocking is most commonly seen in
fire rated assemblies (walls, floors and ceilings). It should be
made of noncombustible materials or a rated assembly that
incorporates combustible materials (rated assemblies have been
tested and are built to very strict standards). There are some
applications that allow standard dimensional lumber (such as 2x4's)
to be used. Check with your specifications or code requirements in
your area for clarification. Most can be placed using standard
forms of attachment, such as nails, screws or staples, and some
require special attachment processes. If special attachment is
required, it will usually be spelled out in the design
specifications (see you plans and details or assembly
specifications). Draft stopping is described in the building codes
(IRC/IBC) as follows: DRAFTSTOP. A material, device or construction
installed to restrict the movement of air within open spaces of
concealed areas of building components such as crawl spaces,
floor/ceiling assemblies, roof/ceiling assemblies and attics. Draft
stopping is required to be located in areas where a transition from
horizontal to vertical or vertical to horizontal occurs. It is also
required in spaces over a prescribed volume or square footage to
limit how much air is available to feed a fire. The intent is to
starve the fire of oxygen before it can grow to a point that it can
cause severe damage to the building or structure. As draft stopping
is used to limit air and not stop fire it can be build of almost
any material approved by the building codes. We commonly use sheet
metal, wood framing members, insulation or expanding foam for draft
stopping. In Conclusion, it would be wise to determine what you are
doing and which process you are required to use. Then, call your
local building inspectors office or design professional of record
and get approval for the application. Hope this helps! Terry