Definition of continuity of fire wall

[Wooly]

So, is the fire rating to be continuous or the wall construction to be continuous? Since the wall / floor-ceiling intersection may (will) contain a different construction what does it mean to be continuous? 2021 IRC

R302.2.3 Continuity. The fire-resistance-rated wall or
assembly separating townhouse units shall be continuous
from the foundation to the underside of the roof sheathing,
deck or slab. The fire-resistance rating shall extend
the full length of the wall or assembly, including wall
extensions through and separating attached enclosed
accessory structures.

 

[Yankee Chronicler]

Both the wall and its fire-resistance rating must be continuous from the foundation to or through the roof. However, the IRC does not define or even mention "fire wall." That's an IBC term.

What you are asking about is the walls separating townhouse units. This is functionally similar to the IBC fire wall, but the IRC doesn't use that term. The section you cited contains the answer to your question. It clearly states that the wall shall be continuous from the foundation to the underside of the roof sheathing, AND that the fire-resistance rating shall extend for the full length of the wall.

 

[steveray]

The rating needs to be continuous...Which complicates the common 2hr bearing wall which is now allowed in the 2021 IRC....Unless it is shaftwall....

 

[Yankee Chronicler]

The rating needs to be continuous...Which complicates the common 2hr bearing wall which is now allowed in the 2021 IRC....Unless it is shaftwall....

That shaftwall system was designed for a reason. IMHO, it's the only approach that makes any sense. Which is why every townhouse project I've seen in the past 20 years used it.

 

[steveray]

And then people go and mess up code....

R302.2.6​

Each townhouse unit shall be structurally independent.

Exceptions:

1. 1.Foundations supporting exterior walls or common walls.
2. 2.Structural roof and wall sheathing from each unit fastened to the common wall framing.
3. 3.Nonstructural wall and roof coverings.
4. 4.Flashing at termination of roof covering over common wall.
5. 5.Townhouse units separated by a common wall as provided in Section R302.2.2, Item 1 or 2.
6. 6.Townhouse units protected by a fire sprinkler system complying with Section P2904 or NFPA 13D.