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  1. #1
    dan orourke's Avatar
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    Default Roof deflection/truss rafters

    Last edited by dan orourke; 01-01-2008 at 09:22 AM.
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    Default Re: Roof deflection/truss rafters

    Dan,

    Hard to say. It looks to me like we are looking toward a valley and the roof sheathing is not properly supported. If I am correct, I would just advise repairs, such as installation of additional blocking. However, I probably would not be specific and recommend repairs, as needed, by a general or framing contractor.

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    Default Re: Roof deflection/truss rafters

    Quote Originally Posted by Gunnar Alquist View Post
    However, I probably would not be specific and recommend repairs, as needed, by a general or framing contractor.
    Keeping in mind that any repairs at this point would likely create roof covering damage, which would also need to be repaired.

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    Default Re: Roof deflection/truss rafters

    I hope that isn't a common wall to the right...


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    Default Re: Roof deflection/truss rafters

    If that's a common wall to the right, the first 4 feet of roof sheathing is required to be fire retardant treated, or, protected with Type X drywall. That 4 feet is not measured from the center of the wall, it is measured from each side of the wall.

    Protecting that is going to be difficult as that also needs to be done to the sheathing beyond the valley, and, that fire separation needs to continue out to and over the soffit, closing the soffit off into separate sides.

    Michael may be seeing something else too?

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    Default Re: Roof deflection/truss rafters

    705.6 Vertical continuity.
    Fire walls shall extend from the
    foundation to a termination point at least 30 inches (762 mm)
    above both adjacent roofs.

    Exceptions:
    1. Stepped buildings in accordance with Section
    705.6.1.
    2. Two-hour walls shall be permitted to terminate at the
    underside of the roof sheathing, deck or slab provided:
    2.1. The lower roof assembly within 4 feet (1220
    mm) of the wall has not less than a 1-hour
    fire-resistance rating and the entire length and
    span of supporting elements for the rated roof
    assembly has a fire-resistance rating of not
    less than 1 hour.
    2.2. Openings in the roof shall not be located
    within 4 feet (1220 mm) of the fire wall.
    2.3. Each building shall be provided with not less
    than a Class B roof covering.
    3. Walls shall be permitted to terminate at the underside
    of noncombustible roof sheathing, deck, or slabs
    where both buildings are provided with not less than a
    Class B roof covering. Openings in the roof shall not
    be located within 4 feet (1220 mm) of the fire wall.
    4. In buildings of Type III, IV and V construction, walls
    shall be permitted to terminate at the underside of
    combustible roof sheathing or decks provided:
    4.1. There are no openings in the roof within 4 feet
    (1220 mm) of the fire wall,
    4.2. The roof is covered with a minimum Class B
    roof covering, and
    4.3. The roof sheathing or deck is constructed of
    fire-retardant-treated wood for a distance of 4
    feet (1220 mm) on both sides of the wall or the
    roof is protected with
    5/8 inch (15.9 mm) Type
    X gypsum board directly beneath the underside
    of the roof sheathing or deck, supported
    by a minimum of 2-inch (51 mm) ledgers attached
    to the sides of the roof framing members
    for a minimum distance of 4 feet (1220
    mm) on both sides of the fire wall.
    5. Buildings located above a parking garage designed in
    accordance with Section 508.2 shall be permitted to
    have the fire walls for the buildings located above the
    parking garage extend from the horizontal separation
    between the parking garage and the buildings.

    705.6.1 Stepped buildings.
    Where a fire wall serves as an
    exterior wall for a building and separates buildings having
    different roof levels, such wall shall terminate at a point not
    less than 30 inches (762 mm) above the lower roof level,
    provided the exterior wall for a height of 15 feet (4572 mm)
    above the lower roof is not less than 1-hour fire-resistance-
    rated construction from both sides with openings protected
    by assemblies having a
    3/4-hour fire protection rating.

    Exception:
    Where the fire wall terminates at the underside
    of the roof sheathing, deck or slab of the lower roof,
    provided:
    1. The lower roof assembly within 10 feet (3048 mm)
    of the wall has not less than a 1-hour fire-resistance
    rating and the entire length and span of supporting
    elements for the rated roof assembly has a fire-resistance
    rating of not less than 1 hour.
    2. Openings in the lower roof shall not be located
    within 10 feet (3048 mm) of the fire wall.

    Read the sections which related to fire walls in Chapter 7.



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    Default Re: Roof deflection/truss rafters

    Quote Originally Posted by Jerry Peck View Post
    Michael may be seeing something else too?
    Well, as that *is* a common (party) wall, the next question is, what is it made of? From the material visible in the picture, it may not be a two hour wall, which opens up a whole new can of worms. (OTOH, it *could* be a two hour wall, which would explain why were are not seeing fire-protection on the underside of the sheeting).

    I'd also like to see a wider angle view of that end of the attic - it's hard to visualize what's going on off to the left from the fragment we can see. Also, a picture of the outside of the roof at that (valley?) would be helpful.

    There, there's the discoloration of the insulation at the eaves. It looks as though the insulation is obstructing any soffit ventilation, so I'm not sure it's a result of the insulation "filtering" air entering through the soffits. Was there a power vent installed in this attic?

    (Later) Here's an enhanced version of what we can see, looks like the eaves are in fact obstructed, but the discoloration is more general.

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    Last edited by Michael Thomas; 09-25-2007 at 10:04 AM.

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    Default Re: Roof deflection/truss rafters

    Quote Originally Posted by Michael Thomas View Post
    (OTOH, it *could* be a two hour wall, which would explain why were are not seeing fire-protection on the underside of the sheeting).
    Michael,

    You've lost me there.

    A 2 hour rated fire wall *is* required to extend 30" through the roof, or, the roof assembly must be protected to a minimum rating of 1 hour.

    Which brings up another point most often missed - I referenced the roof sheathing out to 4 feet, because it is hard enough to get people to even do that, however, the IBC states "2.1. The lower roof assembly within 4 feet (1220 mm) of the wall has not less than a 1-hour fire-resistance rating and the entire length and span of supporting elements for the rated roof assembly has a fire-resistance rating of not less than 1 hour."

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    Default Re: Roof deflection/truss rafters

    That's not a fire wall, not even a 1 hour rated wall.

    At best ... at *BEST* ... that's a draft stop wall.

    Now, if you did not have access to the attic and the fire rating was the ceiling, then the walls would be fire partitions, which only have to go from fire rated floor system to fire rated ceiling system. Being as that is a 'condo', that could have been the intent.

    Is that condo one which is side-by-side-and-one-above-another? Or is it like a townhouse where the condo go from ground floor to the roof?

    The fire rated floor/ceiling system and/or fire partitions/fire walls all depend on that (basically speaking).

    *IF* that condo is built like a town house and the common walls are fire walls or fire partitions, then that is wrong, all wrong.

    *IF* that is like a normal condo building where you only own 'the space' within your walls, floor, and ceiling, then that is wrong in that you should not have had access to the attic.

    The more you say, the more I think about, the worse that gets.

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    Default Re: Roof deflection/truss rafters

    Jerry,

    Looking at first picture, I was considering the possibility that what we are seeing is a compliant wall/parapet/step-roof arrangement, and it is faced on the attic interior(s) with (possibly) non-compliant material installed in such a way that no hint is visible of the compliant structure within it.

    Another possibility is that the observer got turned around (happens, that's why I wear a little luminous compass on my watchband) and that's actually a gable end.

    Neither are likely, but we are not there, either.

    If we were there, we would almost certainly be able to determine what was happening.

    But at our present state of knowledge, we don't know for sure, we can only guess.

    All we *do* know for certain is that this determination should be made, by the HI or someone else.

    ---------

    In the third picture that looks a lot like gypsum board (with a section gouged out of it), but I've never seen it with a dark facing... there appears to be a light colored edge to the material... unless that's a piece of white coax or similar...

    This is increasingly resembling a HI Rorschach test....


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    Last edited by Michael Thomas; 09-25-2007 at 11:56 AM.

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    Default Re: Roof deflection/truss rafters

    Well... there you have it.

    Jerry has laid out the relevant code above.


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    Default Re: Roof deflection/truss rafters

    I have this bookmarked in my notes re: Condo/Townhomes:

    "Single-family dwellings, two-family dwellings, and multiple single-family dwellings (townhouses) are covered by the International Residential Code (IRC).

    The IRC defines a townhouse as “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.” We have found some building officials are allowing two-unit townhouses with separate ownership and property lines dividing the two attached units.

    IRC R317.2—Townhouses further states each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies of not less than one-hour fire-resistive-rating with exposure from both sides for exterior walls with a fire separation distance less than three feet. By 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. (Note: Proposed Amendments to the IRC may allow the fire-resistance rating of the common wall to be reduced to 1-hour provided the building is equipped throughout with an automatic sprinkler system and the common wall does not contain plumbing or mechanical equipment, ducts or vents, and electrical, cable, and telephone installations are installed in raceways and metallic outlet boxes.)

    All multifamily dwellings (apartments, condominiums) are covered by the International Building Code.

    (IBC). The IBC does not differentiate between condominiums and apartments; they meet the same building construction requirements. Both fall under IBC 310.1-Residential Group R-2 as residential occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanent (non-transient) in nature. Typically, walls separating R-2 occupancies shall have a fire resistance rating of 1-hour (½-hour if the building is equipped throughout with an automatic sprinkler system)."

    - http://www.lni.wa.gov/TradesLicensin...ts/Elc0611.pdf

    And have this thread bookmarked with regard to townhouse/condo IBC/IRC differences, "Next By Subject" steps you through the discussion:

    http://www.kcmo.org/codes/ibs/IB142.PDF

    I have to read stuff about once a year to keep it straight - I really wish someone with a more complete understanding than my own would write an article setting all this out in one place.

    Last edited by Michael Thomas; 09-25-2007 at 12:58 PM.

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    Default Re: Roof deflection/truss rafters

    Just found this on UL site.

    UL Announces Revisions to the ANSI/UL 1479 Firestop System Standard
    The ANSI/UL 1479 Fire Tests of Through-Penetration Firestops Standard referenced in Section 712 of the International Building Code and Section R317 of the International Residential Code has been revised to incorporate a change in the construction of samples used to evaluate firestop systems which previously required the use of a chase wall. The systems involved affect penetrations through concrete floor/ceiling assemblies and wood framed floor/ceiling assemblies where the penetrating item is contained within the cavity of a fire-resistance-rated wall assembly.

    Prior to the revision, the test assembly would have been constructed with the through-penetrant in the cavity of a fire-resistance-rated wall assembly located beneath the floor/ceiling assembly. The penetrant was protected by the wall in which it was encapsulated. The standards revision eliminates the chase wall and requires that the penetrant be exposed to the fire during the test. This revision reflects a more realistic worst-case condition.

    This standards revision may impact the F, T and L ratings of currently certified firestop systems that require the penetrating item be enclosed within a chase wall. After September 20, 2007, all firestop systems published in the UL Online Certifications Directory will reflect ratings achieved using the new test criteria. The new ratings will also be reflected in the 2008 UL Fire Resistance Directory.

    What is the impact of this change on designers and code enforcers? In the foreseeable future the impact is minimal since U.S. model building codes reference previous versions of ANSI/UL 1479. The new requirements are more stringent which means that the newly tested systems and previously certified systems should comply with the existing building code requirements. Plan reviewers and designers may notice that systems they previously used for a given hourly rating no longer appear in UL certifications. The absence of a previously existing system utilizing a chase wall indicates that the system did not comply with the new requirements and was removed from the directory/database. There may also be systems where the T rating has been reduced as a result of this change.

    Firestop systems may be accessed on the UL Online Certifications Directory, selecting Fire Resistive Assemblies and Systems under Specific Searches. For more information contact UL's Architectural Services Group at (847) 272-8800, Extension 40057 or at NBK.Architectural.Services@us.ul.com.


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    Default Re: Roof deflection/truss rafters

    Michael,

    I'm sure you noticed my code reference was from the IBC, not the IRC ...

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    Default Re: Roof deflection/truss rafters

    Quote Originally Posted by Michael Thomas View Post
    I started to scan through that and found this right away: (bold and underlining are mine)

    APPLICABLE CODE
    Q: Does the structure contain only one or two dwelling units?
    If the answer is yes, then the IRC is the applicable code. [KCBRC 18-2(c)(1), Exception (a)]


    That is incorrect.

    From the IRC.
    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 townhouses not more than three stories above-grade in height with a separate means of egress and their accessory structures.
    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.


    From the IBC.
    101.2 Scope.
    The provisions of this code shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, maintenance, removal and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures.

    - Exception:
    Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories above grade plane in height with a separate means of egress and their accessory structures shall comply with the International Residential Code.
    TOWNHOUSE.
    A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from the foundation to roof and with open space on at least two sides.

    I.e., A "condominium" does not meet the definition of a "one- and two-family dwelling" or that of a "townhouse". A "condominium" (in this case) *is* a "dwelling unit", but is not a "one- and two-family dwelling' or a "townhouse".



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    Default Re: Roof deflection/truss rafters

    The first thing we need, is to decide if Dan's inspection was a "townhouse" or a "condominium".

    My first first question: is the legal definition (the form of ownership) always the same as the AHJ's determination as to the code status (town home/condo) of the structure.

    What I'm envisioning in the case of this property is a townhome like multi-floor unit (each unit has open space on at least two sides) sharing a common wall with one or two adjacent units. If it's legally held as condo, but is similar in construction to a "townhome", what is it in terms of code requirements?


  17. #17
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    Default Re: Roof deflection/truss rafters

    Just saw this thread...

    Here is an illustration of the requirement:
    (see attachment)

    rr

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    Default Re: Roof deflection/truss rafters

    Quote Originally Posted by Michael Thomas View Post
    The first thing we need, is to decide if Dan's inspection was a "townhouse" or a "condominium".

    My first first question: is the legal definition (the form of ownership) always the same as the AHJ's determination as to the code status (town home/condo) of the structure.
    The method of ownership (legal) does not matter to the code.

    The method of construction (code status) does.

    By that I mean the code considers the building, regardless of whether or not the ownership does, to be separate structures when the building is one entity from ownership of the ground below to the sky above (not in those words, but that's the intent).

    Thus, for the code, considers the structure to be a 'townhouse' if the structure sits on land owned by the structure's owner. The 'structure' is totally separate from another adjoining, attached 'structure', even though they are adjoining and attached.

    A condo, as well as an apartment, is simply a 'space' within a 'structure'. You could 'own' that space (as with a 'condo') or you could rent that space (as with an 'apartment'), and, with a 'condo' all spaces not owned by other individuals are 'common property' owned by the association made up of the owners. With an 'apartment', the owner of the 'complex' owns *ALL*, including each apartment and all common areas.

    A detached one- and two-family dwelling is ... detached ... and owns the ground it sets on, and, usually, additional ground around the structure.

    What I'm envisioning in the case of this property is a townhome like multi-floor unit (each unit has open space on at least two sides) sharing a common wall with one or two adjacent units.
    They are out there, in fact I am inspecting a 43 building, 243 unit, condominium as you describe. The owners of the 'condos' do not own any ground below their structure and do not own their structure (bad terminology, it's not "their" structure). They own 'paint to paint' or 'drywall to drywall').

    If it's legally held as condo, but is similar in construction to a "townhome", what is it in terms of code requirements?
    The construction 'could be' similar, but is not required to be. I will elaborate.

    If that example was a "townhouse", and the owners owned the ground up, including "their" structure (to the center of the common walls), then *EACH* "structure" must be designed to stand alone in case of a fire.

    Let's take a 3 unit townhouse - the center one burns. That structure *is required* to be designed such that the common structural walls *STAY IN PLACE* while that structure burns and falls to the ground. In this case, 2 units (the end two) should still be standing. They may be damaged from smoke and water, but not fire, other than the common walls, which are supposed to still be standing.

    Let's take the same "structure" and it is now a 3 unit condominium - the center one burns. There needs to be 1 hour and 2 hour fire rated partitions separating the unit, but, if the fire is intense enough, the entire "structure" could collapse during a fire, leading to the collapse of all 3 units, with nothing left standing.

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