Wednesday, February 10, 2010

Can classroom trailer roofs hold this much snow?

Who's inspecting the roofs on the MCPS classroom trailers (portables) to insure that they are safe for students when school opens?

MCPS has 551 classroom trailers in use this year. Buildings have a "snow load" rating that determines how much snow the roof can safely hold.

 Montgomery County requires residences and commercial buildings to have a 30 PSF rating. (PSF = pounds per square foot)  The snow load for the classroom trailers in Montgomery County is unknown.  Research indicates that classroom trailer snow loads are typically designed to meet the local building codes.

Montgomery County now has over 2 feet of snow. MCPS is quite possibly approaching or already exceeding the snow load on the classroom trailer roofs.

1/29/2010 Durango Herald:
...Knowlton explained: One inch of snow weighs 1.3 pounds per square foot. So the 28 inches of snow on the roof of the senior center put 36.4 pounds on each square foot...

These photographs were taken on February 11, 2010 of MCPS classroom trailers at 3 different locations.

Here are some school roof issues that have already happened in the region:

2/10/2010 Delaware Online:  School roof one of several collapsing
Faced with unprecedented snow loads on flat roofs around the state and initial reports of some roof collapses already, the Delaware Emergency Management Agency recommends that building owners and residents of those buildings be aware of the weight loads that these back-to-back storms may be creating. Only qualified individuals should be sent to inspect roofs, and all appropriate safety measure must be followed.
2/9/2010  Manassas Public Schools Press Release:  Mayfield Intermediate Closed Due to Compromise in Roof from Heavy Snow



  1. I did some internet research last night on Modular classrooms. Appears the Mfg's tend to build to a 34 pounds per square foot standard.

    Snow weights between 7 and 20 pounds per cubic foot. I believe the snow of the past week would put us at or over the roof load weight limit of our modular classrooms.

    Who in Montgomery County is shoveling off these roofs before classes resume? Who is inspecting these buildings to know if some have not already collapsed or been damaged beyond safe use?

    I think to put students in these classrooms without first clearing the roofs represents a foreseeable danger.

    Bob Astrove

  2. Answer to who was inspecting the roofs on schools?
    No one. MCPS just "looked" at the snow. NO inspections were done after first blizzard and after second blizzard MCPS only "looked" at snow.
    Hardly what is recommended.

    "Only qualified individuals should be sent to inspect roofs, and all appropriate safety measure must be followed."

    Mr. Joseph J. Lavorgna, Acting Director
    Department of Facilities Management

    We have done visual inspections of all of our buildings based on recommendations from our structural engineer and our self insurance
    risk consultant. Our inspections have not revealed any roofs with more snow than they are designed to carry. As far as modular buildings go, we have not seen any that exceed the design limits for snowload that would be cause for concern. The
    melting during the day helps as it reduces the snow load every day.

    The inspections were done last week after the blizzard on Wednesday.


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