Townhouse framing crew set the party wall with regular 5/8" board on one side, stopped it at the second-floor ceiling with the attic open above, and left the joints untaped 'because it's getting covered.' The GC says it's fine because 5/8" is 5/8".

No, the GC is wrong. This violates IRC R302.2 (2021/2024) and IBC 708.3 for townhouse separation walls.

Three fatal defects:

1. Wrong Material: "Regular" 5/8" board is not Type X. Fire-rated assemblies require 5/8" Type X gypsum board (ASTM C1396) on each side. Standard board fails at ~30 mins; Type X holds 1 hour.
2. Missing Continuity: The wall must extend continuous to the underside of the roof sheathing (IRC R302.2.1). Stopping at the 2nd-floor ceiling leaves the attic as an open chimney for fire spread between units.
3. Untaped Joints: Fire-rated assemblies require taped joints and fastener heads (GA-600, ASTM C840). Untaped joints allow flame/gas passage, negating the rating.

Required Fix:

• Demo existing board.
• Install 5/8" Type X full height to roof deck.
• Tape/finish all joints and screws per Level 2 finish minimum.
• Verify attic draftstopping (IRC R302.12) is installed at the party wall line if the attic is shared/concealed.

Do not cover this. The building official will fail the insulation/fire-blocking inspection. If the GC refuses, document with photos and notify the owner/architect immediately—this is a life-safety liability.

No, the GC is not right — this violates fire-resistance requirements for party walls in townhouses.

Under the International Residential Code (IRC) Section R302.2 (2021/2024), party walls separating townhouse units must be constructed as firewalls with a minimum 1-hour fire-resistance rating from foundation to roof sheathing. This requires:

• Continuous gypsum board on both sides of the wall, extending from the foundation to the underside of the roof sheathing (or to a fire-rated attic separation).
• All joints taped and finished (or covered with equivalent fire-rated material) to maintain the integrity of the fire barrier.
• No unprotected openings or gaps — including at the ceiling line where the attic is open.

Stopping the 5/8" Type X gypsum board at the second-floor ceiling and leaving the attic side exposed — especially with untaped joints — creates a significant fire path. Even though 5/8" Type X is the correct thickness for 1-hour rating, the rating depends on full continuity and proper finishing. Untaped joints compromise the assembly’s ability to resist flame and smoke spread.

The IRC requires the firewall to be continuous and unbroken. Leaving the attic open above the wall without a fire-rated separation (like gypsum on the attic side or a fireblock) defeats the purpose. The GC’s reasoning — “it’s getting covered” — is invalid if the covering isn’t fire-rated, continuous, and properly finished.

Corrective action: Install 5/8" Type X gypsum board on the attic side of the party wall, extending to the roof sheathing, with all joints taped and finished, or provide an alternative fire-rated assembly approved by the building official (e.g., fireblocking at the ceiling line with gypsum on both sides). This is not a cosmetic issue — it’s a life-safety code violation.

Consult the local building official or a licensed fire protection engineer for approval of any alternative. Do not proceed without correction.