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Re: Collateral ceiling load

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> From: "David Williams" <dwilliams(--nospam--at)>

> I'm reviewing a submittal from a pre-engineering metal building company for
> a 200'x240' light manufacturing facility.  What's a reasonable ballpark
> number for the collateral load from an automatic sprinkler system and
> electrical lighting fixtures/conduit (no HVAC)? I couldn't find anything
> specific in the controlling code (96 BOCA) or in the IBC.

Collateral load of these items in a "pre-eng" building is identical (or
otherwise determined in the same way) to what you would use in any other
form of construction.

2" wet sprinkler piping and industrial type lighting will usually fall
within 2 psf locally (purlin load) and will generally be close to
insignificant on the frames. Usually, the order will simply spec 2 psf
collateral and it will be applied to everything. Practices at individual
manufacturers may vary but they will accept specific load instructions
provided by the buyer.

The distribution mains (e.g. 6"+ diameter) should be treated as a frame
collateral load only (special consideration to hang from cold formed
purlins) and pipe loads provided. If the weight of the mains is modeled
as distributed over the entire roof area it will definitely be more
expensive and may not be appropriate for local conditions on any
particular member.

> From: "Effland, Greg" <geeffland(--nospam--at)>

> Overall I would think a ballpark of 3 psf collateral (purlins) and 1 psf
> (frames) should be adequate.  If you have large sprinkler mains or other
> HVAC equipment then you might want to specifically design for those
> concentrated loads and not include them in the general xx psf collateral
> load.

They use heavy water in KC :-)
You also want to be very careful about how those larger loads will be
supported and the deflections that they can tolerate.

> From: Roger Turk <73527.1356(--nospam--at)>

> These would, of course, be in addition to the constructed dead load, which
> I use a minimum of 10 psf.

Pre-eng would generally have 3-5 psf for the roof system (purlins,
panel, insulation, bracing, clips, fasteners, etc.) and 2-5 "psf" for
the rafter/beam members constructed dead load.

Most pre-eng designers won't ask too many questions about the real loads
and how those UDLs were determined. Usually, it won't matter ... then
there was the time that a building was quoted with 5psf and, after a
little digging, I found the real load to be a pair of fully loaded
cable trays running down the middle of the span between frames,
supported off the cold-formed purlins.

Paul Ransom, P. Eng.
Burlington, Ontario, Canada
<mailto:ad026(--nospam--at)> <>

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