Townhouse job: the wall between units is a 1-hour rated assembly.

For a 1-hour rated townhouse party wall, you must maintain the fire-resistance rating — regular finish work won’t suffice.

Key differences vs. regular interior walls:

1. Penetrations: - All electrical boxes, pipes, and ducts passing through the wall require approved firestop systems (per IBC Section 714). - Use UL-listed penetration firestop systems — e.g., intumescent collars, fire-rated caulk, or putty. - Regular foam or caulk = fail.

1. Wall Assembly: - Must match the rated assembly (e.g., 5/8" Type X gypsum on both sides, per IBC Table 721.3 or local code). - If adding outlets or modifying, use fire-rated electrical boxes or install a repair ring with proper firestop seal.

1. Finishes: - Joint treatment must be Type X-compatible (no regular joint compound exposed). - Avoid penetrating fasteners (e.g., drywall screws into the opposite side) that could compromise the rating.

1. Inspection: - Schedule a firestop inspection before closing walls. - Document all penetrations with UL system numbers for AHJ review.

Bottom line: Treat every hole like a potential fire path. Seal it with listed materials and keep the wall assembly intact. If unsure, consult the local building department or a licensed firestop inspector — ratings are only valid if installed per listing.

Key differences for a 1-hour fire-rated townhouse separation wall (IBC 706 / IRC R302):

1. Continuous Rating: The wall must run foundation to roof deck (or underside of rated floor/roof above). No stopping at a dropped ceiling. Seal all top/bottom plate penetrations with fire-rated caulk/putty (ASTM E814/UL 1479).
2. Sheathing: Typically 5/8" Type X gypsum each side (or proprietary 1-hr assembly). Standard 1/2" board fails. Check the specific UL/GA listing for screw spacing (usually 7" edges / 12" field) and stagger joints 24" min between sides/layers.
3. Penetrations: Zero unprotected holes. Pipes/Conduits: Use listed firestop collars/sleeves (intumescent wrap for plastic, cast-in or wrap for metal). Electrical boxes: Must be listed fire-rated boxes (metal or intumescent plastic) or standard boxes wrapped with listed putty pads. Back-to-back boxes require 24" horizontal separation or a listed membrane penetration firestop system. Recessed lights: IC-rated, airtight, fire-rated* housings only.
4. Structural Connections: Floor/roof framing cannot break the membrane. Use fire-rated joist hangers or ledger details per the assembly listing. Blocking at rim board must maintain rating.
5. Doors: 20-min rated (1-3/4" solid core/mineral core), self-closing, positive latching, smoke gasketed (UL 1784). Frame must be labeled.
6. Inspection: Do not cover until the rough-in/fire-blocking inspection passes. Inspector verifies sheathing type, screw pattern, penetration seals, and continuity.

Pro Tip: Buy the UL Design Number (e.g., U305, GA-WP-1001) for your exact build-up before framing. Build exactly to that listing. Deviations = failure.