Cesar,
There are a couple of thoughts on your last e-mail.
First, be careful how you use the term "miscellaneous storage", as the
term is defined by NFPA-13 in somewhat narrow terms. A building with
40' high ceilings could - of course - be used for miscellaneous storage,
but it would seem unlikely to me. A quick look at the definition in
3.9.1.14 ('07 edition) would suggest that it is storage that does not
exceed 12'-0" in height, along with some other criteria. I certainly
don't know the parameters of the storage, but from what you described,
it might well be described as "mixed commodities" in Classes I-IV,
rather than "miscellaneous."
There is some flexibility in design when using the criteria from FM
Global, as section 2.2.1.6 of their data sheet 2-0 (2010 edition),
indicates that if you can use standard response storage sprinklers in
ceilings with a slope not exceeding 20 degrees, provided that in-rack
sprinklers are installed. FM Global is more restrictive when no
in-racks are provided, limiting the use of QR or SR storage sprinklers
to ceilings where the pitch is does not exceed 10 degrees. (Table 14,
data sheet 2-0).
FM Global also provides some alternatives and some requirements when the
pitch is in excess of 10 degrees, such as a sprinkler being required
within 3'-0" horizontally of the peak (measured along the slope) when
the pitch exceeds 5 degrees.
It does sound like you're limited in what you can do, to either
requiring a false ceiling, at a flatter pitch, or seeing if the
architects might flatten the roof itself. One thing to be aware of is
that if the roof structure is combustible, and you install a ceiling
below it, you may end up with a combustible concealed space which might
require sprinkler protection as well.
Sorry if that's not what you're looking for.
PARSLEY CONSULTING
Ken Wagoner, SET
760.745.6181 voice
760.745.0537 fax
[email protected] <mailto:[email protected]> e-mail
www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website
César Villavicencio wrote:
> Dear Ron, Todd and Tom:
>
> Appreciate so much your entries.
>
> Yes, the warehouses (in planning stage) will be 40 feet high and they will
> store miscellaneous storage, Commodities I - IV.
>
> If the 18% ceiling slope is a little bit above of the 16.7% established by
> NFPA13, a 30% design area increase will be necessary? If not, what else could
> I do? Ceiling false will go further of the client's budget.
>
> Look forward to hearing from you.
>
>
> Cesar Villavicencio
>
>
>
>
> ________________________________
> From: Ron Greenman <[email protected]>
> To: [email protected]
> Sent: Sun, May 30, 2010 11:08:43 AM
> Subject: Re: WAREHOUSE SLOPED CEILINGS
>
> 2 in 12 is considered flat. Over 2 in 12 is sloped, though, as Todd
> points out, in Cesar's case it is minimal. I wish I could easily point
> you to a head that has design data for sloped ceilings in warehouses
> but you need to define your storage requirement and design approach a
> bit more. If you're 12 feet or under with nothing outside the types
> and classes of commodities (i.e.: nothing too out of the ordinary) a
> head is probably available. If the building is still in the planning
> stage perhaps you can get the architect to lower the slope (anything
> between 2:12, minimum roof slope, and 3.5:12 will be a membrane of
> some sort). There are directions for using standard spray sprinklers
> in factories and warehouses with sawtooth roofs-anybody else here
> remember the fifties-many of the buildings are still around. I cannot
> believe there is no other solution than a costly and unnecessary
> ceiling, I just don't work with storage enough to have a handy
> solution in my pocket.
>
> On Sun, May 30, 2010 at 7:58 AM, Todd Williams <[email protected]> wrote:
>
>> A 16.7% slope is 2.0:12. and 18% slope is
>> 2.16:12. The slope difference is 2" in 12 ft.
>> That is pretty minimal. Could you get a Code mod
>> for that? I would be tempted to go that route and
>> over-design the system a little. I have no idea
>> if the 2:12 was determined by testing and experience or was made up.
>>
>>
>>
>> At 10:38 AM 5/30/2010, you wrote:
>>
>>> Dear Forum Members,
>>>
>>>
>>> NFPA 13 1999 chapter 7-3.1.3. says that
>>> sprinkler system criteria is intended to apply
>>> to buildings with ceiling slopes not exceeding 16.7 percent.
>>>
>>> What if we have warehouses with slopes of 18%,
>>> what should I do? Should I ask a false ceiling
>>> to the client? It is a lot of area, the client will not be happy with this.
>>>
>>> Warehouses Class IV Commodities
>>>
>>> Could I make any adjustment in order to avoid
>>> the construction of false ceiling?
>>>
>>> Please advise.
>>>
>>> Thanks so much.
>>>
>>>
>>>
>>> César Villavicencio
>>>
>>>
>>>
>>> _______________________________________________
>>> Sprinklerforum mailing list
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>>>
>> Todd G. Williams, PE
>> Fire Protection Design/Consulting
>> Stonington, CT
>> 860.535.2080
>> www.fpdc.com
>>
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>>
>
>
>
>
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