# Townhouse Separation???



## jpranch (Dec 16, 2009)

Dose this section meet the intent of 2006 IRC Section R317.2.4 for townhouse separation? Thanks in advance. jp

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## rktect 1 (Dec 16, 2009)

Re: Townhouse Separation???

I'd probably want a few more notes on the section.  The wp 3820 is a 2 hour wall.


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## JBI (Dec 16, 2009)

Re: Townhouse Separation???

It appears to.

The problem I have with it is the 'any classified or non-classified gwb' part. Does that part comply with the design indicated?

Not too many 'generic' UL designs, most are proprietary.


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## Paul Sweet (Dec 16, 2009)

Re: Townhouse Separation???

A strict reading of the code would probably require you to break the plywood subfloor between the units.  On the other hand, it would serve as a backup draftstop if there were gaps in the mineral wool.


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## mtlogcabin (Dec 16, 2009)

Re: Townhouse Separation???



> A strict reading of the code would probably require you to break the plywood subfloor between the units


Agree with Paul it would then meet the strucural independence test plus it would reduce sound transfer, but I believe the floor trusses create a breach in the 2 hour wall requirement


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## ewenme (Dec 16, 2009)

Re: Townhouse Separation???

Not acceptable. The GWB on the walls should be continuous from the bottom to the top. The floor can NOT intersect the wall.  The 2-hour wall with floor joists perpendicular to the wall is the most difficult scenario to achieve the true 2-hour separation.  With the joists parallel to the direction of the wall, it is much easier to achieve the 2-hour separation.  :geek:


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## Moscow (Dec 16, 2009)

Re: Townhouse Separation???

I 100% agree with Carol on this. Tell them to take it back and try again.


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## jpranch (Dec 16, 2009)

Re: Townhouse Separation???

Carol, What about R317.2.4 Exception #5? I have read the commentaries and find the lanuage just a little confusing? If the DP designs a single 2 hour wall would the requirement for structural independence go away? Thanks for the help everybody.  New cross section to follow. jp


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## JBI (Dec 16, 2009)

Re: Townhouse Separation???

I know I'm not Carol but, yes if you use a single two-hour wall the structural independence goes away. Read the section and exception together like one sentence...

Each individual townhouse shall be structurally independent   Except   Townhouses separated by a common 2-hour fire-resistance-rated wall as provided in Section R317.2.

Does that help?


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## TJacobs (Dec 16, 2009)

Re: Townhouse Separation???

Not only do I agree with ewenme on this but the proposal does not comply with "built as an exterior wall".  When one townhouse burns to the ground the remaining common wall framing members will be exposed to the elements, as there is no exterior wall finish of any kind between units.

Unless the separation is a single 2-hour wall, the types of separation wall that I will accept are Gypsum Association WP3810 or 3812 using exterior type x between walls; any of the GA ASW numbers, which are similar to UL U336; or UL V210 or similar.

For example: http://tinyurl.com/ybla4le

or

http://tinyurl.com/ybaw3wp page 14.


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## jpranch (Dec 16, 2009)

Re: Townhouse Separation???

New design. What do you all think?


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## AegisFPE (Dec 16, 2009)

Re: Townhouse Separation???The OP looks a lot like Figure 3 as presented by the Wood Truss Council of America in the Sep/Oct 2006 Structural Building Components Magazine Code Connection Section, titled "Continuity for Dwelling Separations for Townhouses in the IRC."Sounds like some of the strict interpretations offered would only recognize Figures 1 or 2.SBCM-TownhouseWall.JPG[/attachment:2qyr5flp]As for JP's...Hmmm.  I've helped resolved truss joists framing into fire walls, but they didn't look quite like that.

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## mtlogcabin (Dec 16, 2009)

Re: Townhouse Separation???

JP How many units and is there a property line running thru the "townhomes" :?:


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## TJacobs (Dec 16, 2009)

Re: Townhouse Separation???



			
				jpranch said:
			
		

> New design. What do you all think?


Worse...how much of the floor truss is bearing on the top plate?


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## TJacobs (Dec 16, 2009)

Re: Townhouse Separation???



> Sounds like some of the strict interpretations offered would only recognize Figures 1 or 2.


Correct on my end for the reason I gave previous.


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## steveray (Dec 16, 2009)

Re: Townhouse Separation???

*R317.2.1 Continuity* The common wall for townhouses shall be continuous from the foundation to the underside of the roof deck....etc

Doesn't that disallow perpendicular platform framing? Or are those actually listed wall types with the breaks in them? Or is it just a listed assembly above and below with an unlisted penetration?

It should almost be like a firewall with exceptions for the structural independence as listed,no?


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## ewenme (Dec 16, 2009)

Re: Townhouse Separation???

Figure 1 of the second drawing plate is OK. There is still discontinuity in Figures 2 & 3 of those drawings. If the floors run perpendicular to the wall it would be possible to meet the 2-hour requirement by ledgering through the GWB [2 layers] into a secondary ledger inset into the studs.  The problem I see with the first drawing and the Figures 2 & 3 of the second drawing is that the floor sheathing is the only element between the upper and lower GWB, which makes the GWB discontinuous, and therefore subject to the fire rating of the sheathing.

In the first drawing, there are also quarter-inch gaps isolating the drywall. Are these filled with fire caulk?

I still maintain that the floor joists can not penetrate the wall covering on the 2-hour assembly.

Sorry, but I can be stubborn. You'll have to show me. :geek:


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## Builder Bob (Dec 16, 2009)

Re: Townhouse Separation???

I really like the use of a two hour shaft wall - it allows either owner/occupant to trash his/her place and still maintains the required fire separation.


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## jpranch (Dec 17, 2009)

Re: Townhouse Separation???

mt, These townhouses are in blocks of 4 units and there will be a property line separating each unit.


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## mtlogcabin (Dec 17, 2009)

Re: Townhouse Separation???



> These townhouses are in blocks of 4 units and there will be a property line separating each unit.


This is why I asked. When I read the interpretations it is confusing to say the least as to why a property line makes a difference except for the one-hour versus two-hour requirement on the walls

CHAPTER 3

BUILDING PLANNING

SECTION R317.2

IRC Interpretation No. 75-06

2003 Edition

Issued: 04-18-2007

R317.2 Townhouses. Each townhouse shall be considered a separate building and shall be separated by fire-resistance rated wall assemblies meeting the requirements of Section R302 for exterior walls.

Exception: A common 2-hour fire-resistance-rated wall is permitted for townhouses if such walls do not contain plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. Electrical installations shall be installed in accordance with Chapters 33 through 42. Penetrations of electrical outlet boxes shall be in accordance with Section R317.3.

REFERENCED SECTIONS:

R101.2 Scope. The provisions of the International Residential Code for One- and Two-Family Dwellings shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one- and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories in height with a separate means of egress and their accessory structures.

Exception: Existing buildings undergoing repair, alteration or additions, and change of occupancy shall be permitted to comply with the International Existing Building Code.

SECTION R202 DEFINITIONS

LOT. A portion or parcel of land considered as a unit.

LOT LINE. A line dividing one lot from another, or from a street or any public place.

TOWNHOUSE. A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with open space on at least two sides.

! ! ! ! ! ! ! ! ! !

Q: Is a common 2-hour fire-resistance-rated wall, in accordance with the exception to Section R317.2 of the International Residential Code, permitted for separation of individual townhouse dwelling units when separation incorporates a lot line between each townhouse dwelling unit?

A: Yes. The townhouse provisions in the International Residential Code are not based on the presence, or lack thereof, of either a property line or lot line between single-family dwelling units within a townhouse building. Section R317.2 requires separation by two 1-hour fire-resistance-rated walls with exposure from both sides, or by a common 2-hour fire resistance-rated wall per the exception.CHAPTER 3

BUILDING PLANNING

SECTION R321.1

IRC Interpretation No. 41-03

2000 Edition

Issued: 06-08-04

R321.1 Two-family dwellings. Dwelling units in two-family dwellings shall be separated from each other by wall and/or floor assemblies of not less than 1-hour fire-resistive rating when tested in accordance with ASTM E 119. Fire-resistance-rated floor-ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend to the underside of the roof sheathing.

Exception: A fire resistance rating of 1/2 hour shall be permitted in buildings equipped throughout with an automatic

sprinkler system installed in accordance with NFPA 13.

! ! ! ! ! ! ! ! ! !

Q: Is a two-family dwelling with a property line separating the dwelling units required to comply with the separation provisions in Section R321.1?

A: No. The code does not address a property line within an attached two-family dwelling. A dwelling is a building that contains one or two dwelling units. A building line, or property line, is a line established by law, beyond which a building shall not extend. An attached two-family dwelling with a property line between the two dwelling units is considered two separate buildings, located on two separate lots. Two individual dwellings must comply with the fire separation distance required in Section R302.1.

So why aren't townhouses consider seperate buildings when a property line divides them onto different lots?


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## TJacobs (Dec 17, 2009)

Re: Townhouse Separation???

A property line makes no difference.  The difference is, do you buy any old 2-hour wall or don't you.


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