# 302.2 irc 2009



## cda (Mar 25, 2011)

I do not know if this has been discussed

appears the two hour wall betweed townhouse units can go to one hour

1. good idea/ bad idea??

2. does this affect property line issues in anyway????

and also took away the structural independence requirement


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## Yankee (Mar 25, 2011)

cda said:
			
		

> I do not know if this has been discussedappears the two hour wall betweed townhouse units can go to one hour
> 
> 1. good idea/ bad idea??
> 
> ...


With sprinklers


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## cda (Mar 25, 2011)

Ok

Do not have to deal with irc much, but are expecting more townhouses

So install a 13d system and reduce the wall to one hour

Interesting, another reason I do not want to live in a townhouse

So no actual seperation required to constitute the property line??  Except some ul 263 wall


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## NH09 (Mar 25, 2011)

I believe this allowance was also in the 2006 IRC, we have had one builder go this route on a duplex (sprinklered). I am not familiar with the removal of structural dependence, that would be concerning.


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## NH09 (Mar 25, 2011)

Correction, what I meant to say was the removal of structural_ interdependence_.


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## Buelligan (Feb 19, 2015)

I need to bring this post back to the floor.

 I see where 302.2 says that a "common" 1-hour wall can be used if it does not contain any plumbing, mechanical etc. Now I assume the mandatory sprinklers in 313 are why it is stated that "with sprinkler" you can drop to a 1-hour wall? Because the language of 302.2 does not mention sprinklers AT ALL! Therefore if my state removed 313, then a 1- hour wall could still be used as long as it had no plumbing, mech, etc. ?

We had that situation with a previous adoption but luckily they changed that with the last adoption. We only have an exception for One and Two family dwellings and not Townhomes.

My confusion with this comes from the commentary which I know is not enforceable but brought up an interesting question. The commentary states that each unit is considered separate therefore the exterior wall of each unit must be a 1-hour wall. Well the commentary also states the exception allows for a "2-hour common" wall as long as there is no plumbing, mech, etc.

So I am to assume the commentary is the misprint and the actual code language is correct? The intent was to sprinkle ALL townhomes and then allow a 1-hour common wall in place of two individual 1-hour exterior walls? Correct?

Last question, If a 2-hour wall is used can it contain plumbing and or mech. as long as it meets 302.4 for penetrations, correct?


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## Buelligan (Feb 19, 2015)

I need to bring this post back to the floor.

 I see where 302.2 says that a "common" 1-hour wall can be used if it does not contain any plumbing, mechanical etc. Now I assume the mandatory sprinklers in 313 are why it is stated that "with sprinkler" you can drop to a 1-hour wall? Because the language of 302.2 does not mention sprinklers AT ALL! Therefore if my state removed 313, then a 1- hour wall could still be used as long as it had no plumbing, mech, etc. ?

We had that situation with a previous adoption but luckily they changed that with the last adoption. We only have an exception for One and Two family dwellings and not Townhomes.

My confusion with this comes from the commentary which I know is not enforceable but brought up an interesting question. The commentary states that each unit is considered separate therefore the exterior wall of each unit must be a 1-hour wall. Well the commentary also states the exception allows for a "2-hour common" wall as long as there is no plumbing, mech, etc.

So I am to assume the commentary is the misprint and the actual code language is correct? The intent was to sprinkle ALL townhomes and then allow a 1-hour common wall in place of two individual 1-hour exterior walls? Correct?

Last question, If a 2-hour wall is used can it contain plumbing and or mech. as long as it meets 302.4 for penetrations, correct?


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## Francis Vineyard (Feb 19, 2015)

R302.2.4 Each townhouse must be structurally independent and capable of being removed without affecting the adjacent dwelling unit.


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## JBI (Feb 19, 2015)

2006 IRC allowed a common 2 hour wall in lieu of separate 1 hour walls but limited mechanicals, etc in a common wall more severely. There was also an exception that allowed reduction to two 30 minute walls or a single common 1 hour wall with similar restrictions on items within the wall and penetrations of the wall if the units were sprinklered.

2009 IRC mandated all new ResCode buildings to be sprinklered so the 2 hour wall/separate 1 hour walls became moot.

Structural independence never went away. Might have moved, but didn't disappear. The IRC is describing a 'party wall' without using that term.


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## Buelligan (Feb 19, 2015)

Thanks FV, I know that. My question was specific to the separation wall requirements. The OP stated that only a 1-hour wall is required. With Yankee responding that it was with sprinklers. My question is, where does it say that "with sprinklers" that wall can be 1-hour. I assumed that was because the section 313 requires that all units be sprinkled? Because section 302.2 does not mention sprinklers at all.


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## mtlogcabin (Feb 19, 2015)

2012 IRC

R302.2.4 Structural independence.

Each individual townhouse shall be structurally independent.

Exceptions:

1.	Foundations supporting exterior walls or common walls.

2.	Structural roof and wall sheathing from each unit may fasten to the common wall framing.

3.	Nonstructural wall and roof coverings.

4.	Flashing at termination of roof covering over common wall.

5.	Townhouses separated by a common 1-hour fire-resistance-rated wall as provided in Section R302.2.


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## Francis Vineyard (Feb 19, 2015)

Beulligan,

thought that section would be helpful to hang your hat on since Eastern Panhandle apparently did not amennd that section for without sprinklers as John D. pointed out is for splinklered buildings.

In answer to your question where does it say without sprinklers?


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## cda (Feb 19, 2015)

It does not apparently

Maybe a miss ?

They deleted sprinklers but did not add back in the two hour wall

Or did not want to???


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## JBI (Feb 19, 2015)

Another point about the OP is that it was specific to the 2009 IRC. State or local adoption with amendments can lead to a different conclusion.

If a State or Local adoption left out sprinklers and left in the reduced wall provisions, my opinion is that it was an 'ooops'.


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## rogerpa (Feb 19, 2015)

Agree with JBI. The reduction to a 1 hour separation was a "trade-off" to get sprinklers approved. If the AHJ amends out sprinklers, they need to add back 2-hour separation.


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## mtlogcabin (Feb 20, 2015)

Our zoning requires a property line between "townhouse" units therefore the units are not on the same lot and each unit must have a one-hour wall per  R302.1 (see exception 2) and Table R302.1(1) for non-sprinklered buildings (still under the 2006)

In other words no common fire rated walls regardless of the rating.


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