Estimating in Building Construction

(Barré) #1
Masonry 133

to be attached. The coping block and tile are sold by the unit,
and the stone and precast coping are sold by the linear foot.
Figure 11.19 gives the labor productivity rates for installing
masonry accessories.
Special colors, finishes, dowels, dowel holes, and inserts
may be required. Check the drawing and specifications for
these items and note all requirements on the workup sheet.


11–18 Reinforcing Bars

Reinforcing barsare often used in masonry walls to create mul-
tistory bearing wall construction; they are also used in con-
junction with bond beam block and grout in bond beams used
to tie the building together. Reinforcing bars are sold by weight:
The various lengths required of each size are taken off, and the
total weight of each size required is multiplied by the price.
The specifications should be checked to determine the
type of steel required. If galvanized reinforcing bars are
required, the cost for materials will easily double. Also,
galvanized reinforcing bars must be special ordered, thus
they are ordered quickly after the contract has been awarded
(Section 10–3 also discusses reinforcing).

11–19 Cleaning

The specifications must be checked to determine the
amount of cleaning required and the materials that must be
used to clean. The materials exposed inside and outside of
the building will probably require cleaning, while the con-
cealed masonry, such as block used as a backup, generally
receives no cleaning.

Clay Masonry. For brickwork, there should be no attempt
to clean for a minimum of 48 hours after the completion of
the wall. After the minimum time, soap powder (or other mild
solutions) with water and stiff brushes may be tried. When
cleaning unglazed brick and tile, first use plain water and stiff
brush. If these solutions do not work, the surface should be
thoroughly wetted with clear water, scrubbed with a solution
of acid and water, and thoroughly rinsed. Always try the acid
solution on an inconspicuous area prior to using it on the
entire wall. Acids should not be used on glazed facing tile.

Concrete Masonry. Acid is not used on concrete
masonry. If mortar droppings fall on the units, the drop-
pings should be allowed to dry before removal to avoid
smearing the face of the unit. When the droppings have
dried, they can be removed with a trowel, and a final brush-
ing will remove most of the mortar.
The estimator must determine the type of materials
required for cleaning, the area of the surfaces to be cleaned,
the equipment required, the amount of cleaning that will
actually have to be done, and the number of labor hours that
will be required. The better the workmanship on the job, the
less money that has to be allowed for cleaning. When the
color of the mortar is different from that of the masonry
unit, the cost for cleaning will be higher because all mortar
droppings must be cleaned off to get an unblemished facing.

Stone Masonry. Clean stone masonry with a stiff fiber
brush and clear water (soapy water may be used, if neces-
sary). Then rinse with clear water to remove construction
and mortar stains. Machine cleaning processes should be
approved by the stone supplier before they are used. Wire
brushes, acids, and sandblasting are not permitted for
cleaning stonework.

FIGURE 11.18.Flashing Location.

FIGURE 11.19.Labor Hours Required for Installing
Accessories.


Accessories Unit Labor Hours
Wall Reinforcing 1,000 l.f. 1.0 to 1.5
Lintels – Precast Concrete 100 l.f. 4.5 to 7.0
(up to 300 pounds)
Coping, Sills and Precast Concrete 100 l.f. 5.0 to 8.0
(up to 150 pounds)
Wall Ties 100 Pieces 1.0 to 1.5
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