Marc,
That flash card you showed - is that the front and back of the same card?
If it is ... you have your work cut out for you to decipher what ICC is asking - the question is asking about "In a nonsprinklered townhouse" and the answer on the back answers about "where the building is sprinklered" ... might as well ask 'what color are apples' and the answer is 'oranges are orange'.
I have attached two sections from the 2013 CRC, one for townhouse separation and one for two-family dwelling separation. Note that townhouses are defined as "in which each unit extends from foundation to roof" and two-family dwellings are not required to extend from foundation to roof because two-family dwellings may be separated by "by wall and/or floor assemblies".
Townhouse separation is required to be fire-resistance-rated wall assemblies meeting the requirements of Section R302.1 for exterior walls, and that R302.1 references Table R302.1(1) for nonsprinklered andTable R302.1(2) for sprinklered.
The requirements are confusing until what is says is understood - and re-understood each time I forgot what it says after reading them again - but this is what it says:
(From the 2012 IRC (because I can copy and paste from it) (underlining is mine)
- R302.2 Townhouses.
- -
Each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies meeting the requirements of Section R302.1 for exterior walls.
R302.2 refers us to R302.1
- R302.1 Exterior walls.
- - Construction, projections, openings and penetrations of exterior walls of dwellings and accessory buildings shall comply with Table R302.1(1); or dwellings equipped throughout with an automatic sprinkler system installed in accordance with Section P2904 shall comply with Table R302.1(2).
- - - TABLE R302.1(1) EXTERIOR WALLS
- - - - <5 feet separation requires 1 hour fire-resistance rating for each townhouse
- - - TABLE R302.1(2) EXTERIOR WALLS—DWELLINGS WITH FIRE SPRINKLERS
- - - - 1 hour fire-resistance rating for each townhouse permits -0- feet separation
- - - (Note that the two tables are saying the same thing - that each (key word from R302.2)) townhouse shall have minimum 1 hour separation from any other townhouse.)
Now let's go back to R302.2 Townhouses and the exception:
- R302.2 Townhouses
- - Exception:
A common 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E 119 or UL 263 is permitted for townhouses if such walls do not contain 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 and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be installed in accordance with Chapters 34 through 43. Penetrations of electrical outlet boxes shall be in accordance with Section R302.4.
THIS says that EACH townhouse shall have a 1-hour fire-resistance rated wall:
- R302.2 Townhouses.
- -
Each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies meeting the requirements of Section R302.1 for exterior walls.
THIS says that the wall can be a COMMON 1-hour fire-resistance-rated wall ... provided the requirements in the exception are met:
- - Exception:
A common 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E 119 or UL 263 is permitted for townhouses if such walls do not contain 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 and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be installed in accordance with Chapters 34 through 43. Penetrations of electrical outlet boxes shall be in accordance with Section R302.4.
Thus, each side of the common 1-hour fire-resistance-rated wall would have no penetrations except those which meet this:
- R302.4.2 Membrane penetrations.
- - Membrane penetrations shall comply with Section R302.4.1. Where walls are required to have a fire-resistance rating, recessed fixtures shall be installed so that the required fire-resistance rating will not be reduced.
- - - Exceptions:
- - - - 1. Membrane penetrations of maximum 2-hour fire-resistance-rated walls and partitions by steel electrical boxes that do not exceed 16 square inches (0.0103 m2) in area provided the aggregate area of the openings through the membrane does not exceed 100 square inches (0.0645 m2) in any 100 square feet (9.29 m2) of wall area. The annular space between the wall membrane and the box shall not exceed 1/8 inch (3.1 mm). Such boxes on opposite sides of the wall shall be separated by one of the following:
- - - - - 1.1. By a horizontal distance of not less than 24 inches (610 mm) where the wall or partition is constructed with individual noncommunicating stud cavities;
- - - - - 1.2. By a horizontal distance of not less than the depth of the wall cavity when the wall cavity is filled with cellulose loose-fill, rockwool or slag mineral wool insulation;
- - - - - 1.3. By solid fire blocking in accordance with Section R302.11;
- - - - - 1.4. By protecting both boxes with listed putty pads; or
- - - - - 1.5. By other listed materials and methods.
- - - - 2. Membrane penetrations by listed electrical boxes of any materials provided the boxes have been tested for use in fire-resistance-rated assemblies and are installed in accordance with the instructions included in the listing. The annular space between the wall membrane and the box shall not exceed 1/8 inch (3.1 mm) unless listed otherwise. Such boxes on opposite sides of the wall shall be separated by one of the following:
- - - - - 2.1. By the horizontal distance specified in the listing of the electrical boxes;
- - - - - 2.2. By solid fireblocking in accordance with Section R302.11;
- - - - -
2.3. By protecting both boxes with listed putty pads; or
- - - - - 2.4. By other listed materials and methods.
- - - - 3. The annular space created by the penetration of a fire sprinkler provided it is covered by a metal escutcheon plate.
(Note that under exception 2., in 2.3, above for electrical boxes which are any material other than steel (steel boxes are covered in exception 1) that it permits putty pads ... however, finding putty pads which are listed for use with boxes made of material other than steel may be quite difficult, all the putty pads I've seen so far are intended and listed for use with steel electrical boxes - I keep looking for putty pads made for nonmetallic boxes, if you find some, please let me know. I have a newsletter on this issue here:
http://jerrypeck.com/IFCN/2014-10%20IFC ... 20IFCN.pdf .)
Another way to think of it is that townhouses require two 1-hour rated walls back-to-back to separate them from each other ... unless there is a common 1-hour rated wall which meets the limitations for the common 1-hour rated wall.
Does the above help with your question? Minimum townhouse fire-resistance rating separation for EACH townhouse is 1 hour, minimum fire-resistance separation for the COMMON wall is 1 hour and the common wall strictly prohibits some things from being in that common wall.
2013 CRC Townhouse Separation.jpg
2013 CRC Two-Family Separation.jpg
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