Masonry takeoff: units, mortar, grout and reinforcement

Masonry walls are built one unit at a time by skilled trades, so their cost depends on the number of units, the mortar and grout that bind and fill them, the reinforcement and accessories that strengthen and tie them, and above all the labour to lay them. Masonry takeoff starts with wall area by wall type, converts area to units, and then adds the many items that make a masonry wall work: grout, reinforcing, bond beams, lintels, ties, flashings, control joints and cleaning. This lesson works through concrete block and brick veneer, the two most common masonry systems.

Masonry units and modules

Masonry is designed on a module, the nominal size of a unit plus one mortar joint. Laying units on module means openings, corners and wall heights fit whole and half units, saving cutting labour and waste. Takeoff converts net wall area to units using the number of units per unit of area, calculated from the module.

Special units are counted separately: bond beam units, lintel units, corner and jamb units, half units, sash and control joint units, and units with special faces such as split-face, ground-face or scored units. These cost more than standard units and often take more labour, so a takeoff that treats every unit as standard underestimates both material and labour.

Measuring wall area

Masonry walls are measured by area for each wall type: unit size and type, face finish, reinforcing pattern and bond pattern. The gross area is the length times the height, from the top of footing or slab to the top of wall. Openings are deducted according to the measurement rule, typically all openings larger than about 1 m² or 10 ft², and the net area is converted to units. Lengths are measured along the centreline for single wythes, which is the same as the face for thin walls, and corners are counted once.

Mortar allowances vary with joint thickness, bedding method and the unit's shape, so estimators use the table their firm and supplier trust and add a waste allowance, often 10 to 25 %, because mortar is mixed in batches and some is always dropped or hardens before use. Many sites now use pre-blended dry mortar in bags or silos, priced per bag or per tonne or ton, and the takeoff converts mortar volume to the number of bags.

Brick veneer

Brick veneer is a non-loadbearing outer wythe tied to a backup wall of block, steel studs or wood framing across an air space or cavity. Its takeoff includes the brick, the ties that connect it to the backup, flashings and weep vents at the base and over openings, shelf angles or lintels where the veneer is supported, sealant at control joints, and cleaning. Because brick sizes, bond patterns and joint widths vary, the units per square metre or square foot must be calculated for the specified brick, not assumed.

Canadian masonry design and construction are governed by CSA S304 for design, CSA A371 for construction and CSA A370 for connectors, as referenced by the National Building Code and provincial codes. Tie spacing, flashing and cavity details follow these standards and the drawings, and the estimator should read the masonry specification for tie type and spacing.

Grout, reinforcement and bond beams

Reinforced concrete block walls have vertical bars in some cells, which are filled with grout, and horizontal reinforcement in bond beams or joint reinforcement. Grout is measured by the volume of the grouted cells; reinforcement by counting bars as for concrete. Fully grouted walls fill every cell; partially grouted walls fill only the reinforced cells and bond beams.

• Grouted cells: count the cells at the specified spacing, plus cells at jambs, corners and ends, and multiply by the grout volume per cell per unit height.
• Vertical reinforcement: one bar per grouted cell, or as detailed, with laps at dowels and splices.
• Bond beams: continuous horizontal courses of U-shaped units filled with grout and reinforced, at the top of the wall, at floor levels and sometimes at mid-height.
• Joint reinforcement: prefabricated wire reinforcement in the bed joints, often every second or third course, measured by length.
• Lintels: precast, steel or reinforced masonry lintels over openings, counted by length and type.

Masonry labour and other costs

Masonry labour is priced by units laid per mason-hour or by labour-hours per unit of wall area, from the firm's records. Productivity depends heavily on the unit size and weight, wall height and scaffolding, the number of openings, corners and pilasters per unit of wall, the bond pattern, weather, and the quality of the face required. A long, plain wall of standard block goes much faster than a short wall with many openings in split-face units. Mason tenders mix mortar, stock units, build scaffolding and clean up; the ratio of tenders to masons is set by the crew and sometimes by the collective agreement.

A rate of 30 blocks per crew-hour is only an illustration. A crew laying long, plain walls of standard units at a comfortable height may lay considerably more, while a crew working on scaffolding around many openings, pilasters and special units may lay far fewer. The firm's records, broken down by wall type, are the best guide, and the superintendent's view of the specific wall is the best check.

Cold weather has a large effect on masonry because mortar and grout must not freeze before they cure. Canadian and northern US projects often require heated enclosures, heated materials and protection for days after laying, which can add a significant percentage to masonry costs in winter. The estimator should check the schedule and price winter protection where masonry will be built in cold months.

Stone, precast and other masonry

Other masonry systems follow the same logic with their own units. Natural stone veneer is measured by area and bought by area or by weight, with waste depending on whether it is sawn to size or random. Adhered manufactured stone is measured by area with corners counted by length. Glass block is counted from panel dimensions. Architectural precast panels and cast stone sills and copings are usually supply-and-install subcontracts priced from shop drawings, with the general contractor taking off lengths and counts to check the quotes and to coordinate anchors, sealants and flashings at the interfaces.