Materials: Brick, Block, Stone, Mortar & Accessories

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Here's one that matters more than its name lets on — Materials: Brick, Block, Stone, Mortar & Accessories. If you remember one thing, make it this: Masonry is a system, not a pile of units — brick or block, the right mortar type, grout and reinforcement, ties and anchors, and flashing and weeps are specified together, and the wall fails if any one of them is wrong. Do this right and the wall stays strong and dry for the life of the building.

Clay brick

The common standards are ASTM C216 (facing brick), ASTM C62 (building brick for concealed work), and ASTM C652 (hollow brick). Brick is graded for weathering — Grade SW (severe weathering) is the choice for exterior walls anywhere brick gets wet and freezes. A modular brick is nominally 4 x 2-2/3 x 8 inches, so three courses with 3/8-inch joints equal 8 inches and line up with one course of block.

Concrete masonry units (CMU)

Molded concrete in several densities; ASTM C90 covers load-bearing units. The standard block is nominally 8 x 8 x 16 inches (actual 7-5/8 x 7-5/8 x 15-5/8) with two or three cores; stretchers, corners, bond-beam and lintel blocks, and architectural split-face or glazed units each do a job.

Stone

Natural stone — limestone, granite, sandstone, slate, fieldstone — laid as rubble, ashlar, or cut dimension stone. Manufactured stone veneer (cast concrete, usually adhered) has its own standards, and the drainage behind it is where most of its failures begin.

Mortar — ASTM C270

Mortar is cement, lime, sand (ASTM C144), and water. ASTM C270 defines four types, remembered with the word MaSoNwOrK:

• Type M — highest compressive strength; foundations, retaining walls, paving.
• Type S — high strength with good bond; below grade, reinforced masonry, structural walls, and high wind or seismic loads.
• Type N — medium strength, the general-purpose mortar for above-grade exterior and interior walls, veneer, and chimneys.
• Type O — low strength; interior non-load-bearing work and repointing soft historic brick. Stronger is not better: mortar should be weaker than the units it binds so that movement cracks the joint, not the brick. It is mixed from portland cement and lime or from bagged masonry cement or mortar cement.

Grout, reinforcement, ties, and anchors

Grout (ASTM C476) is a high-slump (8 to 11 inches) mix poured into cores and cavities to bond reinforcing steel to the masonry; it is not mortar and the two cannot be swapped. Reinforcing bars go in grouted cells and bond beams. Joint reinforcement — ladder or truss wire in the bed joints, typically every 16 inches — controls shrinkage cracking in block. Veneer ties are corrugated sheet ties on wood-frame homes and adjustable wire ties on commercial work; anchors tie masonry to steel or concrete.

Flashing and weeps

Water will get through a brick wall; the system is designed to drain it. Through-wall flashing of stainless steel, copper, or flexible membrane sits at the base of the wall, under sills, and over lintels, with end dams and a drip edge. Weep holes just above the flashing let water out, spaced no more than 33 inches apart, and a mortar-dropping collection device keeps the cavity open.

Going Deeper (Intermediate)

ASTM C270 lets mortar be specified by proportion (parts of cement, lime, and sand by volume) or by property (laboratory-tested strength, air content, and water retention). TMS 602 requires mortar to be placed within 2-1/2 hours of mixing. The designer sets f'm, the specified compressive strength of the assembled masonry, verified by the unit strength method or by prism tests (ASTM C1314).

Advanced / Pro-Level

Pros match the mortar to the unit and the exposure, not to habit: Type N behind a brick veneer, Type S for reinforced CMU and anything below grade, and a lime-rich mortar — never a hard portland mix — for repointing 1890s brick, where hard mortar makes soft brick spall. They specify flashing that lasts the life of the wall and reject materials like asphalt felt that fail inside a cavity.

Practice Challenge

A spec calls for Type N mortar throughout a project that includes a reinforced CMU foundation wall and a brick veneer above it. What should the mason question? (Answer: Type N suits the above-grade veneer, but ASTM C270 and TMS 602 point to Type S or M for below-grade and reinforced masonry; raise it with the engineer before mixing and keep the two mortars separated on site.)

In Practice

A crew that mixes to the proportion spec, keeps grout and mortar separate, and installs flashing with end dams delivers a wall that passes inspection and stays dry. A crew that uses whatever bags are on the truck delivers callbacks.

Common Mistakes to Avoid

• Using the strongest mortar available because "stronger is better"
• Substituting mortar for grout or grout for mortar
• Skipping end dams and drip edges on flashing
• Mortar bridging the cavity and plugging the weeps

Takeaway: Masonry is a system, not a pile of units — brick or block, the right mortar type, grout and reinforcement, ties and anchors, and flashing and weeps are specified together, and the wall fails if any one of them is wrong.

Educational overview only — not hands-on masonry instruction, a safety program, or a substitute for training under a qualified mason. Follow OSHA 29 CFR 1926 (including Subpart L, 1926.706, and 1926.1153), TMS 402/602 and the adopted building code, your state's contractor licensing rules, the project specifications, and your employer's procedures for your work.