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Fire Rated Construction

mtlogcabin said:
I have seen this design approach before and it could work if it provides a one-hour protection from unit to unit. 1 The fire side is from the ceiling assembly. One layer of Type X has 40 minutes of assigned protection. How much time do you get for the LVL rim board? .
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After 40 minutes your question becomes irrelevant as the structure pulls itself apart due to the collapse of the unprotected floor system.
 
garrett said:
Okay, but the CRC (based on 2009 IRC) does not have mandatory sound transmission requirements. But of course we want to provide a decent level of separation. It is a staggered stud wall assembly.
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California Administrative Code, Title 25, Chapter 1, Subchapter 1; Article 4. Noise Insulation Standards

Ask the AHJ you will find they have adopted Appen. K or they have there own Noise Standards. or the state defalt or California Administrative Code, Title 25, Chapter 1, Subchapter 1; Article 4. Noise Insulation Standards, goes into play.

You must have a 50 min STC By state law
 
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brudgers said:
After 40 minutes your question becomes irrelevant as the structure pulls itself apart due to the collapse of the unprotected floor system.
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Good point but not a code issue.

The majority of wood 2 story homes floor systems are constructed that way. Might be even less than 40 minutes since most SFR do not have Type X gypsum board installed on the ceilings and we know the I-Joist will not last but a few minutes once exposed to the fire.

The floor system should run parrallel to the 2 hour wall
 
mtlogcabin said:
Good point but not a code issue. The majority of wood 2 story homes floor systems are constructed that way. Might be even less than 40 minutes since most SFR do not have Type X gypsum board installed on the ceilings and we know the I-Joist will not last but a few minutes once exposed to the fire.

The floor system should run parrallel to the 2 hour wall
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:agree Why would anyone do it any other way. Makes no sense to penetrate the rated wall with joist.
 
Welcome to the forum Fort. Nice post for your first post. Thanks and hope to see much more from you.
 
mtlogcabin said:
Good point but not a code issue. The majority of wood 2 story homes floor systems are constructed that way. Might be even less than 40 minutes since most SFR do not have Type X gypsum board installed on the ceilings and we know the I-Joist will not last but a few minutes once exposed to the fire. The floor system should run parrallel to the 2 hour wall
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It's relevant if one is trying to achieve fire separation as you mentioned in your post I quoted.
 
gbhammer said:
:agree Why would anyone do it any other way. Makes no sense to penetrate the rated wall with joist.
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Obviously, you have never designed a townhouse...property line to property line is typically the shorter span by a significant amount.
 
brudgers said:
Obviously, you have never designed a townhouse...property line to property line is typically the shorter span by a significant amount.
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I am not a DP just a lowly AHJ, and I am happy that your experience with shorter spans is your problem and not mine.
 
gbhammer said:
I am not a DP just a lowly AHJ, and I am happy that your experience with shorter spans is your problem and not mine.
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Nothing lowly about being a code official - and having worked on many many hundreds of townhouse units, spanning the short direction hardly presents a unique challenge...it's only those lacking experience with the typology who struggle.
 
How would you do it brudgers?

Seems like you know, and it is apparent that the issue is a struggle for many,

not only those with limited experience. There are not any published examples that I could find.

The details in the linked PDF do show some viable options, but requires a rated floor/ceiling, which seems easy enough,

but then you have to maintain that floor/ceiling rating, so you got to think about recessed light fixtures, etc...

and it seems like the whole intent is a continuous fire resistive rated wall, not a floor/ceiling, so perhaps in that regard there should be a better solution.

What do you say about the similar continuous rim-board strategy, but add solid blocking at the face of studs with 5/8" type x.

http://s13.postimage.org/66f8c3g7r/Screen_shot_2012_01_12_at_4_29_22_PM.png
 
Okay, I get it. Thanks though.

Maybe someone else can provide some advice.
 
It's not particularly complicated, and I've seen it done both ways. The wall used for fire separation does not have to be the wall used for bearing of structural members. A continuous wall can provide fire separation, with a traditional platform framed system built along-side to accomodate the floor/ceiling members in the short span. You may lose a bit of square footage, but you may be able to accomodate a more open floor plan with fewer beams/columns by spanning the shorter direction.
 
AegisFPE said:
The continuity of floor sheathing for shear is often an issue.Paul Sheedy had an article in Building Standards that showed it continuing through a single-stud cavity area separation wall, the subject figure is attached.
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The problem the continuity of floor sheathing, is sound transfer.
 
I only see area separation systems in high end condos,

For typical townhouse apartments a common 2x4staggered stud on 2x6 or 2x8 plate is mostly what I see.

Floor sheathing can run thru.

Structural independence not required.

Sound transfer is important to consider, but can't get too hung up on it,

since there are not good published testing results from these types of conditions.

Sure we have STCs for wall and floor assemblies, but not intersections.

Floor joists can run parallel or perpendicular to common wall.

Always best to use 5/8 type x below floor/ceiling, even if rating not required...it costs nothing, just good practice to help reduce risk.

Even if floor joists run parallel, if common wall is used as lateral then there will be perpendicular blocking at 48" o.c. that would penetrate the wall membrane anyway. And since structural independence is not required, it is just the solid blocking that protects the intersection.

Only plan check comment on garret's detail linked is to add fillers between webs of I-joists so no gap where solid blocking butts to it.
 
Some jurisdictions will allow solid blocking, but I've encountered a lot more that say continuity is lost anywhere the rated gypsum board stops. It's easy to cut the blocking to fit between wood joists, but fitting it between I-joists is a lot trickier.
 
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