Can the Dryerbox be installed in a one-hour fire rated wall?

Dryer venting

Author Topic: Can the Dryerbox be installed in a one-hour fire rated wall?  (Read 13614 times)


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The short answer is yes, but we have received calls from home owners that are curious as to what a fire rated wall is and if it applies to them or their specific house. 

A "Rated Wall" is a term used mostly in commercial construction and deals with a "party" wall where two living units abut each other or a corridor wall.  In residential construction the wall between the living area and the garage is in most cases a one-hour wall as well.  These walls need to prohibit the penetration of flames for one hour based on conditions in a specific test.  This barrier is usually achieved with the use of special and thicker sheets of drywall and or a combination of insulation.  When large penetrations exist in this wall additional requirements have to be met by the builder.  These requirements are different for every type of penetration.  Below are the specifics for the Dryerbox.  A more restrictive testing requirement was made part of the 2009 code, which in most areas could of been adopted during the years of 2011-2013 by your local jurisdiction.  You may find it useful to become familiar with both the 06 and the 09 code requirements and to inquire as to what your jurisdiction is claiming as the current code; 2006 or 2009. 

Reply from the manufacturer:
The Dryerbox has been classified by Underwriters Laboratories, for models 350, 425, 3D and 4D for use in Through-Penetration  Firestop System Number W-L-7129.
Respective Link:
Underwriters Laboratories Certifications Directory reference numbers:
XHGK.R21933 (US), XHGK7.R21933 (CANADA) and XHEZ.W-L-7129 (FIRESTOP SYSTEM). 

Quick One-Hour Wall Firestop Instruction Summary
These key components are noted on the instruction sheet that comes with every Dryerbox. The following are highlights to comply with the UL Classification for through-penetration firestop systems.  These comply with the newer 2009 ICC 1 hour F & T requirements.

    To achieve a fire resistance rating (one-hour F & T) 2X6 wood framing is required. The Dryerbox unit must be installed in accordance with the UL Cabinet System listing.
    An extra layer of type-X drywall must be installed in the ID of the stud cavity in which the Dryerbox is located. Drywall must be attached to nailers (minimum 1” X 2”) located on the inside of the cavity wall studs. Secure nailers to wall framing at max 18 in. OC. The screws used to attach the inner layer of drywall shall be spaced a maximum of 18 inches apart.
    The entire depth of stud cavity with Dryerbox® must be filled with R19 fiberglass batt insulation. Additional insulation shall be added within the cavity as necessary to completely fill all voids around the periphery of the Dryerbox and around the dryer vent pipe.
    Use a Roto-zip-bit router tool to cut the drywall leaving a caulk joint for the painter. This void must be caulked or mudded.

This pdf link provides sealed engineer drawings of several wall and stud configurations that may be helpful in your presentation to your building official:

This link provides the necessary documentation for an installation where the 2006 (less stringent) code applies:

For more information, call James from Dryerbox at 561-743-8696
« Last Edit: August 01, 2013, 11:57:42 AM by rickharp »
In-O-Vate Technologies, Inc
Jupiter, FL  33477