116 CHAPTER TEN
Beams and columns are taken off by the linear foot with
each required size kept separately. Anchorage devices, inserts,
and any other special requirements must be noted.
Determine exactly what the suppliers are proposing. If
they are not including the cutting of all holes, finishing of
concrete, welding, or caulking, then all of these items will
have to be figured by the estimator.
10–15 Precast Tees
Precast tees are available as simply reinforced or prestressed.
The shapes available are double and single tee. For the dou-
ble tee, the most common widths available are 4 feet and
6 feet with depths of 8 to 26 inches. Spans range up to 75 feet
depending on the type of reinforcing and size of the unit.
Single tee widths vary from 6 feet to 12 feet with lengths up
to about 100 feet. The ends of the tees must be filled with
some type of filler. Fillers may be concrete, glass, plastic, and
so on. Refer to Figure 10.35.
Most manufacturers who bid this item bid it delivered
and installed either on a square-foot or on a lump sum basis.
One accessory item often overlooked is the special filler
block required to seal the end of the tees.
Concrete fill is often specified as a topping for tees; it
may be used for floors or sloped on a roof to direct rainwater.
The fill is usually a minimum of 2 inches thick and should
have at least a light reinforcing mesh placed in it. Because of
the camber in tees, it is sometimes difficult to pour a uniform
2-inch-thick topping and end up with a level floor.
Specifications. The estimator determines which manu-
facturers are specified, the strength of concrete, the type and
size of reinforcing and aggregate, the finish required, and
whether topping is specified. For reinforcing bars, they must
determine the type of chairs to be used to hold the bars in
place. The bars should be corrosion resistant. The estimator
must determine who will cut the holes and caulk the joints,
as well as what type of caulking will be used.
Estimating. The estimator must take off the square
footage required. If the supplier made a lump sum bid, check
the square-foot price. The square footage required should have
all openings deducted. If the project is bid by the square foot,
call the supplier to check your square footage against their
takeoff. This provides a check for your figures. (However, it is
only a check. If they don’t agree, recheck the drawings. Never
use anyone else’s quantities when working up an estimate.)
When an interior finish is required, the shape of the tee
is a factor: A tee 4 feet wide and 40 feet long does not have a
bottom surface of 160 sf to be finished. The exact amount of
square footage involved varies, depending on the depth and
design of the unit; it should be carefully checked.
The installation of mechanical and plumbing items
sometimes takes some special planning with precast tees in
regard to where the conduit, heating, and plumbing pipes
will be located and how the fixtures will be attached to the
concrete. All of these items must be checked.
The concrete fill (topping) is placed by the general con-
tractor in most cases. The type of aggregate must be deter-
mined, and the cubic yards required must be taken off. The
square footage of the reinforcing mesh and the square
footage of the concrete to be finished must be determined.
From the specifications, estimators determine the aggregate,
strength, type of reinforcing, surface finish, and any special
requirements. This operation will probably be done after the
rest of the concrete work is completed. The decision must be
made as to whether ready-mixed or field-mixed concrete
will be used, how it will be moved to the floor, and the par-
ticular spot on which it is to be placed.10–16 Precast Slabs
Precast slabs are available in hollow, cored, and solid vari-
eties for use on floors, walls, and roofs. For short spans, vari-
ous types of panel and channel slabs with reinforcing bars
are available in both concrete and gypsum. Longer spans and
heavy loads most commonly involve cored units with pre-
stressed wire.
The solid panel and channel slabs are available in heavy-
weight and lightweight aggregates. The thicknesses and
widths available vary considerably, but the maximum span is
generally limited to about 10 feet. Some slabs are available
tongue-and-grooved and some with metal-edged tongue-
and-groove. These types of slabs use reinforcing bars or rein-
forcing mesh for added tension strengths. These lightweight,
easy-to-handle nail, drill, and saw pieces are easily installed
on the job over the supporting members. A clip or other spe-
cial fastener should be used in placing the slabs.
Cored units with prestressed wire are used on roof
spans up to about 44 feet. Thicknesses available range from 4
to 16 inches with various widths available, 40 and 48 inches
being the most common. Each manufacturer must be con-
tacted to determine the structural limitations of each prod-
uct. The units generally have high fire resistance ratings and
are available with an acoustical finish. Some types are avail-
able with exposed aggregate finishes for walls.Specifications. The type of material used and the manu-
facturer specified are the first items to be checked. The materi-
als used to manufacture the plank, type and size of reinforcing,
and required fire rating and finish must be checked.
The estimator should also note who cuts the required holes
in the planks and who caulks the joints, and the type of caulking
FIGURE 10.35.Double Tees Detail. to be used. If topping is required, the thickness, reinforcing,