FLOOD07624

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: Raising and Moving the Slab-on-Grade House
• Date: 1/1/1990
• Prepared For: State of Colorado
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

METHODS AND TECHNIQUES

Raising and Moving the Structure -
A system used extensively in Florida,
where construction with concrete block is
widely practiced, involves excavating the soil
from beneath the structure, inserting a system
of two, heavy steel longitudinal beams and
numerous, closely spaced cross members, and
cutting the plumbing connections and any
footings or piers encountered. Procedures
will vary somewhat from structure to struc-
ture, and must be planned on a case-by-case
basis. The slab-on-grade is typically designed
to be continuously supported by the underly-
ing soil. This demands careful planning for
the systematic removal of the soil and for
support of the slab throughout the process as
shown in the photograph on page 16. Special
care is required for concentrated loads such as
fireplaces and chimneys as indicated in the
photograph on page I7.
Hydraulic jacks are placed at three
points beneath the steel beam system, two
near one end of the structure beneath each of
the main longitudinal beams, and one at the
other end of the structure mid-way between
the two longitudinal beams. The lifting points
are thus positioned so as to form an isosceles
triangle in the horizontal plane of the slab.
The three-point lift minimizes the possibility
of cracking of the slab due to twisting or
differential movement.
If the structure is to be raised in place
without relocation, once it is raised to the
desired elevation the jacks are replaced with
timber cribbing. If it is to be moved to an-
other location, large wheeled doIlies are
inserted at the two jacking points under the
main beams, and the hauling equipment takes
the load at the third jacking point centered
between the main beams. At the new loca-
tion, the moving equipment is replaced by
timber cribbing supporting the structure at the

desired elevation, and the new foundation is
constructed beneath it. The photograph on
page 22 shows one of the timber cribbing sup-
ports placed beneath a main longitudinal
beam.

Cutting the Structure -
If piers or portions of grade beams
must be removed, they are first scored along
appropriate cut lines with an air saw equipped
with a concrete blade, then broken with a
hammer. Photographs on page 26 show
where previously existing piers have been cut
away. Any reinforcing steel encountered is
cut with a torch.
If the structure's size or shape prevents
raising or moving it in one piece, it can be cut
into manageable segments. If the structure is
too tall for vertical clearances available along
the route, the roof can be partially or com-
pletely removed. It is frequently necessary to
remove chimneys for this reason. It may also
be advantageous to remove the floor from at-
tached garages, many of which are con-
structed at a slightly lower elevation than the
remainder of the house.
Cuts in walls are made between studs
in frame construction. In concrete block con-
struction, a whole section of blocks may be
removed, and replaced at the new site, some-
times incorporating a new pilaster at the
location of the removed blocks.
Vertical cuts through roofs are usually
made between rafters or joists, or immediately
alongside a rafter or joist. Reconnections at
cuts between rafters are made with 2x6, or
2x8 timbers laid flat against the underside of
the roof. Reconnections of cuts immediately
adjacent to a rafter can be made by nailing
additional rafters to the old rafter.
Cuts through the slab are made with
"street saws" equipped with diamond blades.
Usually no attempt is made to reconnect the
slab at the new site. The joints will merely be

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