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Thread: Openings at imagined property line

  1. #1
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    Openings at imagined property line

    FIRE-WALL2.pdf

    I'm trying to decide the best place to draw the imaginary property line between two buildings on the same lot... The two buildings were created by a Fire Wall (due to floor area of buildings).

    What makes this tricky is that the exterior walls of the two buildings are perpendicular to each other. I want openings in those walls and want them unprotected if possible. No openings are allowed within 3' of the PL. Is this measured as in attached Scenario #1 where walls perpendicular to the imaginary PL don't require protected openings? Or is it more of a "setback" situation as in Scenario #2?

    If Scenario #2 is correct, can I measure the allowable unprotected openings as I have shown? Treating the wall as three segments, one from 0-5' one from 5'-10' and one 10'+ and then comapring the portion of the opening in that segment to whats allowed?

    Any insight would be appreciated!

    Thanks,

    Neal

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    Sawhorse
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    Measure perpendicular from the face of the wall, like Scenario 1, not perpendicular to the property line as shown in Scenario 2 (see "Fire Separation Distance" in 702.1).

    You end up with 1 wall that is on the property line, and with the other wall 5-feet away from the property line per 706.5.1(2).

    You could continue to step the property line to benefit one wall.

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    When in doubt read the definitions 702.1

    FIRE SEPARATION DISTANCE. The distance measured
    from the building face to one of the following:
    1. The closest interior lot line;
    2. To the centerline of a street, an alley or public way; or
    3. To an imaginary line between two buildings on the property.

    The distance shall be measured at right angles from the face
    of the wall.


    so THE Wall is Each Wall cause one wall can't not be the Wall

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    Sawhorse
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    why can't the building 2 leg be the property line? Can't figure out why you'd want to "establish a property line" at the angles you're suggesting. Whatever you do, needs to remain consistent forever.

    Establishing this arbitrary line may very well limit what development can occur in the future... the whole keeping it simple theory.
    (PE)ach
    some days are just that..

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    Why not use 706.5.1 (1). The way that I read this is that you simply rate the wall for four feet on each side of the intersection. Looking at your drawing, you have no openings within four feet so you would just have to extend your rating hatch on the exterior walls and make that portion one-hour. 706.5.1(1) does not require you to draw a property line.

    IBC 2009 Edition referenced.

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    Architect1281,

    That's what I was looking for but my 2006 IBC doesn't have the line "The distance shall be measured at right angles from the face of the wall" That line IS in the 2009, interesting that there is no little vertical bar next to the addition indicating new text...
    Last edited by nealderidder; August 18th, 2011 at 10:30.

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    Peach,

    I'm not really establishing a property line that will affect development in the future. I'm following the requirements of 704.3 (2006). The fire wall was necessary because the floor area was too large for one building (there's a lot of building not shown in my sketch). If you use a fire wall to separate one building into two you are then required to establish this "imaginary" property line in order to determine fire separation distance and thus the required protection for openings. If I make the building 2 leg the property line I wouldn't be able to have ANY openings there.

    Neal

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    JustReid,

    I wish! Section 706.5.1 (2) is what's giving me trouble. I get what is required I'm just not sure exactly how to "measure" the distance.

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    AegisFPE,

    That's exactly what I want to do, I'm looking for justification in the code for measuring the fire separation distance at right angles to the walls. I get the feeling my BO is going to ask me to justify not protecting those openings.

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    Thanks All!

    I'm going to go with measurements at right angles to the walls (as suggested by AegisFPE and Architect1281) and use the change in 702.1 2009 IBC that specifically points out the method of measurement as justification. This project is under 2006 IBC but this will give the BO something to hang his hat on.

    Best regards,

    Neal

  11. #11
    Sawhorse
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    It is in 702.1 of the 2006 under the definition of "Fire Separation Distance."
    The distance shall be measured at right angles from the face of the wall.
    The section on fire walls states that these walls are used to create separate buildings. As such, you would have two buildings on the property. Therefore, per Item 3 of the above-referenced definition, you would have an imaginary property line between the two buildings extending from the terminus of the fire wall between the two buildings from which the Fire Separation Distance should be assessed.

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    Don't mean to kill a horse here.

    In reading this, I interpret that a wall facing a property line has to be 5 feet.

    But if you have a wall coming from a propertyline. I could have an opening on a wall, perpendicular to the property line, within 5 feet, that isn't rated, etc. Because the line perpendicular from this wall is 100 feet away.

    This always gets my mind going in cirlces saying this cannot be, but as written, it must be allowed.

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