Estimating in Building Construction

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