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Framing and Windows
Draftstopping and Fireblocking Party Walls


A common wall, also known as a party wall, fire wall, fire separation wall, townhouse separation wall, or tenant separation wall, can be described as a fire-resistance rated wall that extends continuously from the foundation to the underside of fire protected roof sheathing. These are most common in multi-family units.


The purpose of a common wall is to prevent the spread of fire from one unit to another, and to allow the collapse of a unit that is on fire without structurally impacting the adjacent unit.
Proper air sealing this common wall is critical in a fire situation because it allows less transfer of smoke and hot gas in one direction, and less oxygen to feed the fire in the other direction.


Other benefits to a well-sealed party wall:

  • Energy efficiency and comfort is improved by reducing infiltration and the energy required to condition that air.
  • IAQ is improved by reducing odor and contaminated air transfer from adjacent units or common areas.
  • Reduced sound transfer between units.
  • If lobby doors or unit windows are left open, air-sealing greatly reduced or eliminates the chimney or stack effect upward through the building.