2 SFRs, 2 lots Zero Fire separation distance

[grl04]

I have two single family residences - up against each other- zero fire separation distance from the lot line. They want to use a 2 hour-rated Party Wall (2 - 5/8" Type X GWB at both sides UL listing WP 3820 ) but their detail shows a ledger attached to the party wall on either side with floor joists hanging from the ledger.

Is this acceptable? The party wall integrity is interrupted to my interpretation.

I would appreciate some feedback.

 

[mtlogcabin]

Will these work for your design?

Wood Construction Connectors

<p>Wood construction connectors are specifically designed to provide support for applications in wood structural systems. These metal (steel) connectors are crucial for securing wood-to-wood, wood-to-masonry or wood-to-concrete connections.</p>

www.strongtie.com

 

[mtlogcabin]

Will these work for your design?

Wood Construction Connectors

<p>Wood construction connectors are specifically designed to provide support for applications in wood structural systems. These metal (steel) connectors are crucial for securing wood-to-wood, wood-to-masonry or wood-to-concrete connections.</p>

www.strongtie.com

 

[grl04]

Will these work for your design?

Wood Construction Connectors

<p>Wood construction connectors are specifically designed to provide support for applications in wood structural systems. These metal (steel) connectors are crucial for securing wood-to-wood, wood-to-masonry or wood-to-concrete connections.</p>

www.strongtie.com

@mtlogcabin well, not really.

My question can a party wall have penetrations? As the party wall runs North to South and the floor joists go West to East. The ledger for the floor joist is bearing on the party wall.

 

[grl04]

I made the call that this doesn't comply with a definition of a party wall.

 

[cda]

I have two single family residences - up against each other- zero fire separation distance from the lot line. They want to use a 2 hour-rated Party Wall (2 - 5/8" Type X GWB at both sides UL listing WP 3820 ) but their detail shows a ledger attached to the party wall on either side with floor joists hanging from the ledger.

Is this acceptable? The party wall integrity is interrupted to my interpretation.

I would appreciate some feedback.

As in Duplex??

How many stories?

 

[Joe.B]

If a building is split by a lot line I thought they were supposed to be designed to be structurally independent so that if a fire damaged one building it could collapse without pulling the other building with it or (theoretically) if one lot was sold the new owner could modify/demo/expand their building without adversely affecting the other structure? So in essence you're really building two separate buildings that happen to be nearly touching and share some non-structural elements such as siding and roofing. Never actually seen anything built this way so I don't have experience with this, hence I am asking, not stating.

 

[steveray]

I'm with Joe B....Sounds like you need structural independence...Shaft wall with bearing wall on either side....With the meltaway clips...

 

[mtlogcabin]

First the IRC does not have "party walls" as part of the code
A town house is 3 or more units and that is where a common 2 hour wall is mentioned
Since you have a lot line running between the units with a zero setback I believe you need to follow
TABLE R302.1(1) EXTERIOR WALLS for each unit which will require a one-hour wall for each unit

As the AHJ we do have 2 unit townhouse lots that zoning requires a parent lot with sub-lots and we do allow the 2-hour common wall and the floor joist usually run parallel with the common wall or they drop the floor joist down and hang them from the concrete foundation wall

 

[steveray]

I guess we do allow an IRC 2hr common wall separation:

(Amd) R302.2.2 Common walls. Common walls separating townhouses shall be assigned a fireresistance
rating in accordance with 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 be
tight against exterior walls and the underside of the roof sheathing.

But the rating would have to be maintained and would not break at the ledger...

 

[grl04]

First the IRC does not have "party walls" as part of the code
A town house is 3 or more units and that is where a common 2 hour wall is mentioned
Since you have a lot line running between the units with a zero setback I believe you need to follow
TABLE R302.1(1) EXTERIOR WALLS for each unit which will require a one-hour wall for each unit

As the AHJ we do have 2 unit townhouse lots that zoning requires a parent lot with sub-lots and we do allow the 2-hour common wall and the floor joist usually run parallel with the common wall or they drop the floor joist down and hang them from the concrete foundation wall

Agreed.

There is a lot line running in between them and they need to be built as separate structures hence I'm good with either 2- one hour walls or an h-stud where the structures are also protected with a continuous barrier.

I have done the 2-hour common party wall where in their joist run parallel to the wall or its dropped where they are hung from the foundation wall.

The detail that they have show that the joists are perpendicular to the common 2-hour wall and hanging off a ledger attached to that common wall.

My take on it is that the penetration of that ledger (it's on both sides) interrupts the continuity of the fire separation.

 

[mtlogcabin]

My take on it is that the penetration of that ledger (it's on both sides) interrupts the continuity of the fire separation.

I agree

 

[Robert]

Agreed.

There is a lot line running in between them and they need to be built as separate structures hence I'm good with either 2- one hour walls or an h-stud where the structures are also protected with a continuous barrier.

I have done the 2-hour common party wall where in their joist run parallel to the wall or its dropped where they are hung from the foundation wall.

The detail that they have show that the joists are perpendicular to the common 2-hour wall and hanging off a ledger attached to that common wall.

My take on it is that the penetration of that ledger (it's on both sides) interrupts the continuity of the fire separation.

I had a similar situation in a 2 hour elevator shaft. Plan checker allowed adding 2 -2x blocks between the joists at the ledger. The added wood thickness created the 2 hour comprable. In hindsight it may have been better to use a 4 or 6x ledger instead of adding the blocking.