Maintaining Fire Resistance During a Repair
Robert Grupe / October 2015
Q: Someone damaged the gypsum panels on a fire-resistive wall that I had just completed. How do I repair the wall and maintain the fire resistance?
A: This is a question that, unfortunately, is a fairly common occurrence. A small hole that penetrates into one side and only one side of a wall assembly must be repaired. A contractor completes an installation, only to find that another trade has damaged the completed work. It can also occur during the day-to-day operations of the completed structure. The proper repair procedure will depend on the size of the damage and the required fire resistance rating. The guiding principle for any repair is that damaged material must be replaced, and the material that is used in the repair must be equivalent to the original material in type and thickness. That means if three layers of gypsum panels are affected, all three layers should be replaced with the same type and thickness of gypsum. Further, it must be installed to resist the rigors of a fire test or event.
Fortunately, the Gypsum Association has published a document that provides guidance on how to make the repair. That document is known as “GA 215-15, Repair of Fire-Rated Gypsum Panel Product Systems,” and it is available from www.gypsum.org.
Fire-resistive construction is based on an assembly concept. That means that all the components within the assembly (studs, fasteners and gypsum panels) work together to attain the rating. That requires that the installation follow what was tested to meet that rating. It then follows that any deviation from what was tested or any modification to an installed wall can adversely affect the fire-resistive (and acoustical) rating. It is therefore required that the damaged gypsum panel be replaced with a panel with the same core as what was installed. Type X or proprietary Type X panels are panels for consideration. The damaged panel must be removed effectively eliminating any broken gypsum core. The geometric shape of the gypsum panel patch must be exactly same as the hole in the installed panels. Any insulation in the cavity that is damaged should be removed and replaced in kind.
For fire-resistive assemblies it is important to understand that any gypsum panel patches must be mechanically attached to the installed wall. The patch cannot be installed with joint tape and compound alone. The GA suggests a steel track be used for back-blocking. This track should be installed inside the stud cavity and along the edge of the hole. The gypsum patch is then attached to the track with fasteners of proper length spaced 8 inches (200 mm) on center. The joint between the patch and the existing material can then be finished with joint tape and compound.
Many wall assemblies require multiple layers of gypsum panels on one side of the framing to achieve the intended fire rating. The gypsum panel joints are staggered from one layer to the next. The same is true for any repairs. The repair joints should not line up from one layer to the next. To accommodate that requirement, the base layer repair patch should be smaller than the face layer.
The above solution is for smaller holes in walls and ceilings. Should the damaged area be greater than 100 square inches (700 square centimeters) in 100 square feet (10 square meters), then the GA recommends that the damaged area in the wall or ceiling be removed to adjacent framing. The document goes on to provide guidance for inspection of framing and replacement of materials.
The Gypsum Association has included photographs in GA 215 on the proper procedure and sequence for repairing small holes. If the gypsum panel is one that is proprietary to a single manufacturer, it is suggested to consult with that manufacturer.
The important fact to remember is that fire-resistive walls are critical for life safety. It is critical that these rated walls, or possibly floor/ceiling, and roof/ceiling assemblies must be installed and maintained to achieve fire resistance. Any damaged gypsum panels should be inspected and repaired. Any repair must be done that preserves the fire integrity of the assembly. For new construction, the installation and repair procedure will come under the watchful eye of the Authority Having Jurisdiction; most commonly this is the local building official. That individual has the right and responsibility to approve any solution or installation of repairs. In some cases, it might be advisable to consult with them prior to completing the repair procedure.
Robert Grupe is acting as AWCI’s director of technical services. He can be reached at (703) 538.1611 or firstname.lastname@example.org.