NCCER Masonry flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Type M mortar

Highest-strength mortar (2500 psi) with the highest portland cement content. Used for below-grade walls, retaining walls, and masonry in severe weathering or high-wind zones.

Type N mortar

Medium-strength mortar (750 psi) with balanced cement and lime. The general-purpose choice for above-grade exterior walls in moderate weathering and for interior load-bearing walls.

Mortar sand ratio

Sand is measured as 2.25 to 3 times the combined cementitious and lime volume. Too much sand weakens the mix; too little makes it stiff and hard to tool.

Grout lift limits

Fine grout is placed in lifts no higher than 5 ft; coarse grout in lifts no higher than 12 ft 8 in. Each lift is consolidated before the next is placed.

Nominal brick dimensions

A modular brick is 3 5/8 x 2 1/4 x 7 5/8 in. actual, becoming 8 x 2 2/3 x 8 in. nominal with a 3/8 in. mortar joint.

Concrete block module

A standard block is 8 x 8 x 16 in. nominal, giving 8 in. of wall height and 16 in. of length per unit. One square foot of wall face needs about 1.125 blocks.

Running bond

Every course is offset by half a unit from the course below, so vertical joints never align. This is the most common bond for single-wythe walls and gives good strength.

Flemish bond

Each course alternates a stretcher and a header. The pattern is decorative and historically common in brick facades, providing both appearance and cross-wall tying.

Stack bond

Units are stacked with vertical joints aligned from course to course. It has little inherent strength and requires horizontal joint reinforcement or a backup wall.

Wall tie spacing

Cavity wall ties are placed at 16 in. maximum vertically and 24 in. maximum horizontally. Ties must be embedded in both wythes and slope to drain moisture outward.

Weep hole spacing

Weeps are placed at 24 in. maximum on center and immediately above flashing at the base of a cavity wall, keeping the drainage path open.

Flashing upstand height

Through-wall flashing turns up the backup wall at least 8 in. and laps the flashing below. The upstand prevents water from bypassing the flashing into the wall.

Mortar joint thickness

Bed and head joints are typically 3/8 in. thick. Joints thicker than 1/2 in. reduce mortar strength and are not permitted in structural masonry.

Masonry cement versus portland

Masonry cement is a factory blend of portland cement and plasticizers, while portland-lime mortar is mixed on site. The two systems are not interchangeable in a specified mix.

Efflorescence cause

Water-soluble salts migrate to the masonry surface and crystallize as a white deposit. It signals moisture movement through the wall, not necessarily defective units.

Corbel limits

Each course of corbelling projects no more than one-third of the unit width, and total projection is limited to one-half the wall thickness for solid masonry.

Plumb tolerance

Masonry walls must be plumb within 1/4 in. in 10 ft and within 3/8 in. total per story. Engineered work may allow 1/2 in. in any 20 ft.

Course level tolerance

Individual courses must be level within 1/4 in. in 10 ft. Bed joint thickness on adjacent courses should not vary more than 1/4 in. over that distance.

Concave joint tooling

A round or V-shaped tool compacts the mortar face and sheds water. This joint profile gives the best weather resistance on exterior masonry walls.

Mortar cube test

Field samples of mortar are cast in 2 in. cubes or 3 in. cylinders, cured, and tested at 28 days. Results confirm the mix meets the specified compressive strength.

Prism test purpose

Prisms built from the project's units, mortar, and grout are tested to verify the compressive strength of the assembled masonry, not just the individual materials.

Grout slump range

Grout slump measured at the point of placement must be 8 to 11 in. Slump outside this range indicates a mix that will not flow into voids or will segregate.

Grout cube testing

Grout samples are cast in molds and tested at 28 days for compressive strength, commonly 2000 psi minimum. Cubes are cured like the wall before testing.

Anchor bolt inspection

Verify bolt diameter, embedment depth, and spacing before grouting. Bolts must be set in grout, not mortar, and positioned with templates to match the sill plate.

Water penetration test

A spray rack applies about 5 gal/hr per square foot to a 10 ft by 10 ft wall area for at least 4 hours, and the interior face is checked for leakage.

Weep hole verification

Final inspection confirms weep holes are open and unobstructed. Mortar droppings in the cavity or blocked weeps trap water and cause interior leakage.

Flashing lap check

Inspection confirms flashing laps are correct and the upstand is sealed to the backup. Reversed laps or unsealed ends let water run behind the flashing.

Rebar placement check

Verify bar size, spacing, lap lengths, and cover before grouting. Rebar must be tied in place and centered in the cell so grout fully surrounds it.

Mortar joint thickness check

Measure bed and head joints during inspection; they should be about 3/8 in. and not exceed 1/2 in. Oversized joints weaken the wall and are a common rejection item.

Masonry cleaner test

Before cleaning a whole wall, test the cleaner on an inconspicuous area to confirm it removes mortar smears without etching or discoloring the units.

Cavity width tolerance

The cavity between wythes is typically 2 in. wide with a tolerance of plus or minus 1/2 in. Ties and flashing must accommodate the actual cavity width.