Common walls separating townhouses shall be assigned a fire-resistance rating in accordance with Section R302.2, Item 1 or 2. The common wall shared by two townhouses shall be constructed without plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend to and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be in accordance with the California Electrical Code. Penetrations of the membrane of common walls for electrical outlet boxes shall be in accordance with Section R302.4.
- Where a fire sprinkler system in accordance with Section R313 is provided, the common wall shall be not less than a 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E119 or UL 263.
- Where a fire sprinkler system in accordance with Section R313 is not provided, the common wall shall be not less than a 2-hour fire-resistance-rated wall assembly tested in accordance with ASTM E119 or UL 263.
- Where roof surfaces adjacent to the wall or walls are at the same elevation, the parapet shall extend not less than 30 inches (762 mm) above the roof surfaces.
- A parapet is not required where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is more than 30 inches (762 mm) above the lower roof. The common wall construction from the lower roof to the underside of the higher roof deck shall have not less than a 1-hour fire-resistance rating. The wall shall be rated for exposure from both sides.
Each individual townhouse shall be structurally independent.
- Foundations supporting exterior walls or common walls.
- Structural roof and wall sheathing from each unit fastened to the common wall framing.
- Nonstructural wall and roof coverings.
- Flashing at termination of roof covering over common wall.
- Townhouses separated by a common wall as provided in Section R302.2, Item 1 or 2.