Can a SIP be used to build a residential party wall in a townhouse-type building?  (Party wall = the shared wall between units, running from foundation to roof.)  Party walls usually have special code requirements.  The standard construction, I think, is a double stud wall with staggered studs, with a double layer of fire-rated gypsum on either side, and fire stops in the stud cavities at the right places.  Most of that would seem unneccessary with SIPs -- just the double gypsum on either side.  But building inspectors don't always look favorably on doing things differently than standard practice.  Would it be done with a single SIP wall, or two SIP walls with a gap?  Would some sort of spacer be required to maintain that gap?

Yeah, I know I could dig through code books to try to figure this out, but somebody here probably knows, and I'm a little lazy.  ;)

If the SIP assembly has been tested and approved for that use, then they should be allowed. Ours have been tested and approved for a load bearing 1 hour rated assembly up to 3 stories high.

Other approvals

¨  SSTD-1299 Non Porous Impact Protective Systems “State of Florida requirements for Educational Facilities” Chapter 5, section 5.4 Paragraph (d) Structural Missile Impact Criteria (Heavy Impact Missile at 50 feet Per Second)

¨  ASTM E-1886 - 02 “Standard Test for Curtain Walls: Large Missile Impact and Exposed to Cyclic Pressure Differentials” (+/-) through 4500 cycles of each positive and negative pressure

¨  ASTM E-1996 – 02 “Standard Specification for Curtain Walls Impacted by Windborne Debris in Hurricanes”

¨  ASTM E-72 “Vacuum Chamber Structural Load Tests” Shear Modulus of Panel Core, Shear Strength of the Panel Core, Bending Strength, Connection Strength

¨  ASTM-1592 & UL 580 “Standard Test Method for Steel/Metal Roof systems by Uniform Static Air Pressure Difference

¨  UBC-26-3 and UL-1715 Room Fire Test Standards

ASTM E-119-00a “Fire Test of Building Construction & Materials” Test Conditions also described by Testing Standards UBC-7-1/1997, UBC 263 a and the NFPA 251 (National Fire Protection Association) for 1 Hour Fire

besides structure and fire separation issues, I think sound transmission is more important than R-Value in a party wall. One usually assumes that the house next door will be conditioned and near the temperature that you want to maintain. You want their heat (or cooling) but you do not want their sound. Maybe a SIP is not the best choice?

WE have a 6 inch metal sip party wall that is in a duplex. We have two crews one working at finishing each side. Unless they are banging directly on the party wall it is hard to hear a thing from side to side, saws hammers , screw guns etc. After firring strips are up and the electrical is done and you still want more sound proofing that just install 1 in sound board before dry wall. I have my office lined with one inch sound board on the wall that is next to the laundry and I can't hear anything from the laundry room and that is a regular framed wall.

Here is a side note that I always thought would be a money maker for someone building rental duplexes or town homes. You will only heat a home to hot or cool it to cold. So, I would calculate the utilities at 5 cents per sq ft for here in Florida, then add $100 to that figure, adding that to the rent and rent them utilities included, except water. For a 1500 sq ft duplex you would add $175 to the rent. You would make an extra $100 per month and the renters would think that they had the best deal in town.

Donaldson,

Chris Kavala has often described his approach of (as I understand it) metal Z strip firring to create a shallow cavity for wiring.  He explains that it also reduces sound transmission.  Is that similar to what you're describing?  If so, what do you sue to fir it out?

Very respectfully,
Larry

RTR,

It is exactly what I am describing. Using a 1 1/2 inch "high hat" metal furring strip leaves a 1 1/2 inch air space behind the drywall. This is a 2 inch space with the 1/2 inch dry wall. which allows for using shallow electrical boxes and switches and running your wiring just like it was a block wall. This also allows you to place 1 inch sound board between the firring strips, on the "party wall" if you want or feel the need. In our Duplex we did not put any sound board at all and it is very quiet between the two unites. In my office I put sound board in between the metal studs as it was not a sip wall at all and the inch sound board cancels out the washer and dryer noise just fine..