Repairing damage to drywall in fire-rated wall systems
Learn how to repair holes and other damage to drywall to preserve the integrity of fire-rated wall assemblies
Fire-rated wall systems are designed to slow the spread of fire and smoke in buildings, providing critical time for evacuation and fire response. Often during construction these fire-rated walls can become damaged. When this happens, it’s important to perform repairs that maintain the fire-rated performance of the wall assembly.
In this blog post, Sam Halverson, construction services manager with the 1-800-NATIONAL® Construction Services team, outlines the various types of damage that may occur in fire-rated drywall assemblies and provides recommendations for their respective repairs to preserve the integrity of fire-rated systems.
1. Surface damage: Abrasions, dents and gouges
Minor damage, such as surface abrasions, small paper tears or dents, can typically be repaired easily with joint treatment products.
Repair procedure
- Carefully remove any loose or torn paper.
- Apply a setting-type joint compound over the damaged area, ensuring all depressions are filled, and create a smooth surface.
- Once dry, sand and prepare the area for primer and paint as necessary.
This straightforward approach addresses common surface damage without requiring the replacement of gypsum board.
Pro Tip: Unlike ready mix compounds, setting-type joint compounds are primarily composed of gypsum, the main component of drywall, which reduces the transfer of heat through calcination.
2. Small, visible holes: Flush patch method
For small holes, up to 100 square inches in a 100-square-foot area, you can use a flush patch to repair the damage.
Repair procedure
- Square off the damaged area.
- Frame the cutout with studs or runner track.
- Cut a patch the same size as the cutout from the same type of gypsum board used in the original construction.
- For multiple layer systems, stagger vertical and horizontal patch joints by at least 12", and fasten the vertical edges to the stud framing.
- Mechanically fasten and secure the patch to the framing installed in the wall cavity.
- Apply tape and joint compound to finish the perimeter of the patch.
This method works well for small holes to maintain the performance of fire-rated gypsum board assemblies. For larger holes, however, replacing the original gypsum board back to the framing is required.
Source:The Purple Book II, page 120
3. Hidden holes: Surface-applied patch (blowout patch)
An alternative to the flush patch is the surface-applied patch, which is used for fixing holes above ceilings or other areas hidden from view.
Repair procedure
- Cut a piece of gypsum board that overlaps the damaged area by at least 12" at the top and bottom and is wide enough to secure to the studs on each side.
- Secure the patch to the studs on each side of the damaged area with Type S screws spaced every 8".
This repair method is simpler than the flush patch but is not appropriate where aesthetics is a concern.
4. Gaps at joints
When installed, gypsum board products should be abutted with moderate contact between one another but not forced together. In the event gaps occur between the boards, follow the recommendations below.
Repair procedure
- For gaps less than 1/8" in fire-rated assemblies, fill the gaps with setting-type joint compound.
- In non-fire-rated assemblies, gaps less than 1/8" can be filled with ready mix or setting-type joint compound. Gaps greater than 1/8" but less than 1/4" must be filled with setting-type joint compound.
Ensuring the joints are properly filled is critical to maintaining the fire-rated barrier’s integrity.
Pro Tip: Setting type joint compounds shrink significantly less than ready-mix compounds.
5. Nail and screw holes
When installing gypsum board, nails and screws can occasionally miss the framing and create small holes into the wall cavity.
Repair procedure
- For 1-hour and 2-hour partitions, fill any nail or screw holes with setting-type joint compound.
This simple repair method prevents heat transfer through the hole.
How to repair holes in shaftwall partitions
When damage occurs to cavity shaftwall systems (UL design W419), it’s critical to follow specific repair procedures to maintain the fire rating of the shaftwall system.
For penetrations through 1" shaftliner or when dealing with crushed or broken core conditions:
- Square off the damaged area.
- Cut and fit plugs of 1" shaftliner into the cutout area, ensuring a tight fit.
- Coat the back of a piece of Gold Bond® Fire-Shield® Gypsum Board (either 1/2" Type C or 5/8" Type X) with setting compound and center it over the patched area, extending 12" above and below the damage on all sides.
- Secure the Gold Bond Fire-Shield Gypsum Board to the studs on each side with 1" Type S screws 12" o.c.
- Repair the face panels with a surface-applied patch as described above.
When the damage to the shaftliner panel exceeds 100 square inches, the panel needs replacing.
- Carefully remove the damaged panel.
- Score and snap a replacement shaftliner down the middle and fold it into place between the studs.
- Coat the back of a piece of Gold Bond Fire-Shield Gypsum Board (either 1/2" Type C or 5/8" Type X) with setting compound and center it over the patched area, extending 12" above and below the damage on all sides.
- Secure the Gold Bond Fire-Shield Gypsum Board to the studs on each side with 1" Type S screws 12" o.c.
- Repair the face panels with a surface-applied patch as described above or replace as needed.
Source:The Purple Book II, pages 92–93
For repairs to the shaftliner panel from outside of the shaft, follow the repair procedure below:
- Square off the damaged area.
- Cut and fit plugs of 1" shaftliner into the cutout area, ensuring a tight fit.
- Coat the back of a piece of Gold Bond® XP® Fire-Shield® Gypsum Board or Gold Bond® eXP® Shaftliner with setting compound and center it over the patched area, extending 12" above and below the damage on all sides.
- Secure the shaftliner panel to the studs on each side with 1" Type S screws 12" o.c.
- Install steel angles to the studs as required for shaftliner attachment.
- Replace the face panels as required.
To replace the shaftliner from the outside of the shaft side:
- Carefully remove the damaged panel.
- Score and snap a replacement shaftliner down the middle and fold it into place between the studs.
- Coat the back of a piece of Gold Bond XP Fire-Shield or eXP Shaftliner with setting compound and center it over the patched area, extending 12" above and below the damage on all sides.
- Secure the shaftliner panel to the studs on each side with 1" Type S screws 12" o.c.
- Repair the face panels with a surface-applied patch as described above or replace as needed.
Source:The Purple Book II, pages 94–95
2-hour area separation wall hole repair
For National Gypsum’s h-stud area separation wall system (UL Design U347) follow the steps outlined below:
- Square off the damaged area.
- Cut and fit plugs of 1" shaftliner into the cutout area, ensuring a tight fit.
- Coat the back of a piece of Gold Bond Fire-Shield Gypsum Board (either 1/2" Type C or 5/8" Type X) with setting compound and center it over the patched area, extending 12" above and below the damage on all sides.
- Secure the Gold Bond Fire-Shield Gypsum Board to the studs on each side with 1" Type S screws 6" o.c.
Hole repair details for 2-hour area separation walls
Source:The Wood Book, page 115
When the damage to the shaftliner panels exceeds 100 square inches, the panel needs replacing:
- Carefully remove the damaged panel.
- Score and snap a replacement shaftliner down the middle and fold it into place between the studs.
- Coat the back of a piece of Gold Bond Fire-Shield Gypsum Board (either 1/2" Type C or 5/8" Type X) with setting compound and center it over the patched area, extending 12" above and below the damage on all sides.
- Secure the Gold Bond Fire-Shield Gypsum Board to the studs on each side with 1" Type S screws 6" o.c.
Shaftliner replacement for 2-hour area separation walls
Source:The Wood Book, page 116
Technical expertise from National Gypsum
Properly repairing damage to fire-rated drywall systems is essential to preserving their performance and the safety of building occupants. Whether you’re dealing with minor surface damage or more significant penetrations, following these best practices will help ensure that your fire-rated walls continue to offer the protection for which they were designed.
Download The PURPLE Book® and The Wood Book™ today as helpful resources for common design and construction challenges. Need to talk through a repair solution? The 1-800-NATIONAL Construction Services team is ready to help.
