Understanding the UL Fire Resistance Directory
Attendee questions
Understanding the UL Fire Resistance Directory webinar on August 22, 2024
What is the best resource for finding STC ratings for wall assemblies in UL listings?
Our technical resource guide, The SoundBook®, includes tested assemblies for STC ratings and references UL ratings.
How can I find modifications to tested assemblies on the UL Product iQ site?
The “General Information for Fire-resistance Ratings – ANSI/UL 263 Certified for United States Design Criteria and Allowable Variances” outlines permissible modifications. You can find this information by clicking the first link at the top of any UL design on the UL Product iQ site. Please note you will need to log in to access the site.
Where can I find the requirements or restrictions for attaching equipment or conduit to the face of the fire-rated (GWB) wall, including the type of screws, exposure and spacing of the connectors?
UL does not evaluate anything attached to a fire-rated wall. There is no reason, in our opinion, to expect surface mounted equipment to affect the fire rating.
Can we get a copy of this presentation?
Please contact ngcaia@nationalgypsum.com to receive a PDF version of the presentation. The webinar recording is also available on demand.
In the webinar, it was mentioned that insulation may be added to 1-hour-rated floor-ceiling assemblies provided an extra layer of gypsum board is added to the assembly. How can I determine the required thickness of the gypsum board to add?
According to the “General Information for Fire-resistance Ratings – ANSI/UL 263 Certified for United States Design Criteria and Allowable Variances” Section III, Item 17 found on UL’s Product iQ online certification directory, the additional layer of gypsum board should be of the same type as shown on the individual design. You can find this information by clicking the first link at the top of any UL design on the UL Product iQ site. Please note you will need to log in to access the site.
Is The PURPLE Book® II in addition to The PURPLE Book® I or a replacement?
The PURPLE Book® II is the second edition of The PURPLE Book®.
How can I download copies of The PURPLE Book® and The SoundBook®?
These technical reference guides can be downloaded on National Gypsum’s Design & Resource Center.
Are all your sound-tested designs included in The SoundBook® or are there additional designs that aren’t published there?
National Gypsum’s acoustical testing is ongoing, and we’ve conducted tests since the publication of the book. If your specific assembly is not found in The SoundBook®, please contact your Construction Design Manager for an estimate.
Is it okay to tape and mud over paper that is peeled away from the gypsum core?
Tape is not required to repair gypsum board where the paper has peeled away. We recommend skimming directly over the damaged area with setting type joint compound.
What is the purpose of the hose stream test in the ASTM E119 fire test?
The hose stream test, required for most vertically tested assemblies per ASTM E119, ensures a fire-rated wall assembly can withstand the pressure of water from a hose used to extinguish a fire without being compromised.
Are countersunk screws acceptable? If this poses an issue, what is the solution?
If a fastener is countersunk, then an additional fastener should be added above or below the countersunk fastener. The faulty fastener can remain in place or be removed, and the hole filled with setting type joint compound.
In a G500 assembly, I’ve noticed installers often place a strip of drywall across the top track of a fire partition wall. However, these strips are not always straight, making it difficult for the straight edge of a new sheet to align properly. They usually just tape and mud the gap. Are you okay with this approach?
UL rated G500 series designs do not address the intersection of the ceiling and fire-rated wall. Fire-rated walls should terminate at the underside of an uninterrupted ceiling membrane or continue to the deck above.
Does UL allow for additional layers of gypsum board and the addition of furring channels to a UL fire-rated assembly?
UL allows for additional layers of gypsum board to be added to a fire-rated assembly. However, UL does not have a provision for the addition of furring channels to a fire-rated design. That said, most UL fire-rated designs do include an option for incorporating channels.
Why does the addition of insulation in a horizontal assembly require an extra layer of gypsum board?
Insulation in plenum or joist space of a floor-ceiling assembly can keep heat close to the ceiling during a fire, causing the gypsum board to calcine more quickly.
Is it okay to have a max 1/8" gap at the vertical joints between sheets of gypsum board when the joint lands on a framing member? What about the joints that are not on framing?
All gypsum boards should be in moderate contact with each other.
At what temperature does the gypsum calcination process begin?
The calcination process for gypsum board typically begins at 125 degrees. The gypsum board will not transmit temperatures above 212 degrees until fully calcined.
Given that Type X gypsum board is most often 5/8" thick, is all 5/8" gypsum board considered “Type X”? Or is there also regular 5/8" gypsum board?
Most 5/8" gypsum board is Type X. Some manufacturers, including Gold Bond Building Products, have at least one 5/8" gypsum board product that is not Type X. Gold Bond High Strength Fire-Shield 30 Gypsum Board is Gold Bond's only product that is 5/8" that is not Type X. Type X gypsum board is not always 5/8” thick. This NGC Blog post describes the difference between Type X vs. Type C gypsum board.
Can 15/32" plywood be added to a 1-hour wood stud partition with gypsum wall and keep the original 1-hour rating?
Plywood can be added to any fire-rated wall assembly, per UL’s “General Information for Fire-resistance Ratings – ANSI/UL 263 Certified for United States Design Criteria and Allowable Variances,” Section VI, Item 6. You can find this information by clicking the first link at the top of any UL design on the UL Product iQ site. Please note you will need to log in to access the site.
Does U465 in parenthesis on the presentation slides mean the assembly is both V438 and U465?
Yes, U465 is a UL fire-rated design with multiple gypsum board manufacturers listed. V438 is a proprietary UL fire-rated design with only Gold Bond products listed.