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  1. #1
    Join Date
    Jul 2018
    Location
    New Jersey
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    7

    Default ISO Class III...??? (or I)

    hello again...

    In my travels this week, I inspected a building that had:

    Steel Roof Trusses
    Metal Stud Exterior Walls, sheetrocked on the inside; & sided w/ T1-11 wood panels on the exterior (at least I believe they were metal studs...looked like 2X6 nominal...maybe cold-formed load bearing exterior wall metal studs?)

    The building was constructed in the 1990's (according to the insured).

    Is this an ISO Class III (light non-combustible)...???...or is it ISO Class I simply because it's frame construction?

    (reason I'm asking is...I've never come across steel roof trusses on a frame building)

    thanx,


    MF

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  2. #2
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: ISO Class III...??? (or I)

    Quote Originally Posted by Mark Forman View Post
    Is this an ISO Class III (light non-combustible)...???...or is it ISO Class I simply because it's frame construction?

    (reason I'm asking is...I've never come across steel roof trusses on a frame building)
    My first question is - Why are you asking the ISO Classification? For what purpose?

    After that, you did not give enough information - here are some links which may either help or confuse the matter (based on what is written as what is Class I and Class III):

    http://www.upfro.com/Inspectors/ISO%...on%20Class.htm (note that Class I says "light-gauge metal)

    https://www.guc.com/Data/Sites/1/med...efinitions.pdf

    https://www.irmi.com/docs/default-so...n.pdf?sfvrsn=6

    http://www.amrisc.com/Amrisc%20pdfs/...scriptions.pdf

    https://www.sorm.state.tx.us/wp-cont...sification.pdf (may be the best help as it provides a relationship to the building code types of construction)

    I would start be finding out what type of construction the building is, then use the last one above to relate that to the ISO Classification.

    However, as a home inspector, if you are a home inspector, why are your identifying ISO Class/Type of Construction?

    Last edited by Jerry Peck; 07-14-2018 at 05:14 PM. Reason: "(based on what is written as what is Class I and Class II)" ... should have been "Class I and Class III"
    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
    Join Date
    Sep 2014
    Location
    New Jersey
    Posts
    57

    Default Re: ISO Class III...??? (or I)

    ISO 1 - Frame Construction (Wood walls & Roof, foundation construction does not matter) Masonry Veneer or accents still count as ISO 1.

    ISO 2 - Joisted Masonry - Free standing Masonry shell with wood floors and joists, flammable roof. (If structure burns, masonry walls remain)

    ISO 3 - Light noncombustible - Structure does not add to fire (fuel) load of building but does not resist fire well. Light steel construction.

    ISO 4 - Masonry Noncombustible - Free standing masonry walls with noncombustible floors and roof.

    ISO 5 - Modified Fire Resistive - Walls between fire divisions in structure have 1-hour fire rating. Noncombustible structure.

    ISO 6 - Fire Resistive - Walls between fire divisions have 2-hour fire rating, otherwise noncombustible structure.

    Peak Inspection Services | Over 34 Years of Contractor Experience!
    Residential Inspections | Commercial Inspections
    Office: 908-750-6789 | www.peakinspectionservices.com

  4. #4
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: ISO Class III...??? (or I)

    Quote Originally Posted by Steve Payson View Post
    ISO 1 - Frame Construction (Wood walls & Roof, foundation construction does not matter) Masonry Veneer or accents still count as ISO 1.

    ISO 2 - Joisted Masonry - Free standing Masonry shell with wood floors and joists, flammable roof. (If structure burns, masonry walls remain)

    ISO 3 - Light noncombustible - Structure does not add to fire (fuel) load of building but does not resist fire well. Light steel construction.

    ISO 4 - Masonry Noncombustible - Free standing masonry walls with noncombustible floors and roof.

    ISO 5 - Modified Fire Resistive - Walls between fire divisions in structure have 1-hour fire rating. Noncombustible structure.

    ISO 6 - Fire Resistive - Walls between fire divisions have 2-hour fire rating, otherwise noncombustible structure.
    Source?

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  5. #5
    Join Date
    Sep 2014
    Location
    New Jersey
    Posts
    57

    Default Re: ISO Class III...??? (or I)

    Quote Originally Posted by Jerry Peck View Post
    Source?
    I used to do commercial risk management & loss control inspections back in the day and what I posted above (although it can get more detailed based on hourly fire resistance ratings) is what every insurance company I dealt with used to determine ISO class.

    https://www.assetworks.com/wp-conten...ifications.pdf

    https://www.sorm.state.tx.us/wp-cont...sification.pdf

    By the way, I never came across any insurance company that included "light-gauge metal" to qualify a structure to be in the ISO 1 classification.

    Peak Inspection Services | Over 34 Years of Contractor Experience!
    Residential Inspections | Commercial Inspections
    Office: 908-750-6789 | www.peakinspectionservices.com

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