Masonry work includes construction with clay bricks, concrete bricks and blocks, clay tiles, and natural and artificial stone. This work is now typically performed by subcontractors who supply the labor, materials, and equipment required to complete the work.
Estimating the costs of masonry work involving products other than standard bricks and concrete blocks but the work is mostly the task of specialists. A thorough knowledge of masonry construction is a definite prerequisite to the performance of good estimating. Particular attention has to be paid to items such as masonry bond and mortar joint treatment, which have considerable effect on material usage, waste factors, and mortar consumption. A minimum knowledge of terminology is required before masonry specifications can be properly interpreted to determine such things as the type of units required and their requisite features, together with aspects of the numerous accessories associated with masonry work.
The units of measurement for masonry are generally the number of masonry pieces such as concrete blocks or, in the case of bricks, the number of thousands of clay bricks. Calculating the number of masonry units involves a two- stage process:
- The area of masonry is measured.
- A standard factor is applied to determine the number of masonry units required for area measured.
Estimators need to be familiar with the definition of the scope of work for the masonry trade in their geographical location. This trade scope is often defined for a geographical area by the local masonry association and may also be found in the bid depository rules of construction associations in many cities.
This definition lists the items of work that are included in the masonry trade and those items of work that are excluded from the work of the masonry trade. Knowledge of this scope of work is essential to the person estimating the masonry work for the specialized masonry trade contractor. Knowledge of the masonry scope, together with the scopes of all other sub trades, is also valuable to the general contractor’s estimator who is receiving sub trade prices.
Bricks are made of different materials and manufactured by different methods, and they can be used in many different ways in the construction process. All of these factors will influence the price of the masonry, but the main factors affecting the measurement of brick masonry are the size of the brick units, the size of the joints between bricks, the wall thickness, and the pattern of brick bond utilized.
Bricks are available in a great number of sizes, but the Common Brick Manufacturers Association has adopted a standard size with the nominal dimensions of 2-1⁄4 by 3-3⁄4 by 8 inches (57 mm by 95 mm by 203 mm). Bricks of this size are referred to as “standard bricks”.
Concrete masonry comprises all molded concrete units used in the construction of a building and includes concrete brick, hollow and solid block, and decorative types of block. Historically, many of these units are manufactured on the local level, and industry standards are not always followed. There is considerable variation in shapes and sizes available.
General Rules to Estimate Masonry Work:
- Measure all quantities “net in place” and do not deduct for openings that are less than 10 square feet
- Separately measure masonry work that is circular on plan.
- Masonry work includes scaffolding and hoisting.
- Masonry work shall be measured separately in the following categories: i)Facings ii)Backing to facings iii)Walls and partitions iv)Furring to walls v)Fire protection
- The cleaning of exposed masonry surfaces shall be described and measured in square feet.
- Measure silicone treatment of masonry surfaces in square feet, stating the number of coats required.
- Measure expansion joints or control joints in masonry in linear feet, and fully describe these joints. Specify any required joint filler material (caulking) in the description of the joint system.
- Measure mortar red in cubic feet or cubic meters, and provide details of any admixtures required.
- Separately measure colored mortar where it is required.
- Measure wire reinforcement in masonry joints in linear feet or meters, and fully describe. “Ladder” or “truss” reinforcement can be used; specify which is required.
- Enumerate anchor bolts, sleeves, brackets, and similar items that are built into masonry, and fully describe these items. Built-in components together with the lintels and similar items mentioned in the following notes may be supplied and installed by the masonry trade; alternatively they may be supplied by the miscellaneous metals sub trade and only installed by the masonry contractor.
- Measure building in lintels, sills, copings, flashings, and similar items in linear feet or meters, and fully describe. Specify the type of material involved; not only can the material cost vary but also the installation cost can vary with different types of material.
- Enumerate weep holes where they are required to be formed using plastic inserts and such like.
- Measure rigid insulation to masonry work in square feet or square meters, describing the type and thickness of material
- Bricks shall be measured in units of 1000 bricks, describing the type and dimensions of bricks.
- Separately measure facing bricks.
- Measure in linear feet or meters bricks required to be laid in any other pattern than running bond; for example, soldier courses or brick-on-edge courses.
- Enumerate and fully describe brick ties.
- Enumerate concrete block masonry units, stating the type and size of blocks.
- Separately enumerate special units required at corners, jambs, heads, sills, and other similar locations.
- Measure in cubic yards or cubic meters, and fully describe loose fill or foam insulation to block work cores.
- Measure bond beams in linear feet.
- Measure concrete to core fills and bond beams in cubic yards or cubic meters, stating the strength and type of concrete to be used.
- Measure in linear feet or meters reinforcing steel to core fills and bond beams, stating the size and type of rebar to be used.