LAYING THE FOUNDATION FOR YOUR MODULAR BUILDING
by: Jerry Brosius
NTA, Inc.
717-761-6207
jbrosius@msn.com
Proper design and installation of the foundation system is critical to the
optimal performance of any building. Modular classrooms are not exempt from
these considerations. When the foundations are properly designed and installed,
the structural integrity of modular classrooms will be equivalent to traditional
site built construction.
Footings
Most temporary classrooms are placed on piers constructed from masonry block.
The location of the piers is critical to the performance of the classroom
design. The manufacturer typically provides a suggested blocking points plan
that will locate the piers and identify the building loads that each location
must support. These are the loads generated by the occupants and the weight of
the building to include snow load when applicable.
On multi-section classrooms, the blocking point locations along the mating lines
are extremely critical. An example would be a sixty foot long building comprised
of two modules and containing two thirty foot classrooms. Two achieve the thirty
foot clear spans in each classroom, columns would be placed in the endwalls and
the wall separating the classrooms. The loads at the columns are much higher and
will require larger footings and piers.
Footings are typically constructed with concrete. Excavation is generally
provided through the use of augured holes and the concrete is placed into a
cardboard tube designed to serve as the formwork. The base of the footing must
be on undisturbed soil and it must extend to the frost line or bedrock. The
minimum depth for any footing is twelve inches. It is strongly recommended that
the final foundation design be prepared by a registered engineer based on the
information supplied with the building and with the local conditions. These
local conditions would include the frost depth and soil capacity.
Anchorage
Most temporary classrooms utilize a system with steel straps secured to the
frame that transports the structure. These straps are connected to an auger that
is embedded into the soil. The manufacturer’s blocking point plan will provide
suggested tie-down locations. These locations are based on the capacity of the
ground anchors and wind speed design of the building. Proper design and
installation of the anchoring system provides safety and durability through the
effective transfer of wind loads to the ground. A design based on local
conditions would be included with the footing design prepared by the engineer.
LAYING THE FOUNDATION FOR YOUR MODULAR BUILDING
Site Work
The manufacturer will provide instructions for completion of the building on
site. On a typical two section classroom, this would include securing the
sections together at the floor and roof line. Other considerations would be the
final electrical and plumbing connections.