Masonry is the method of building structures by stacking individual units, such as bricks, stones, or concrete blocks, and binding them together with mortar. It is one of the oldest and most durable construction techniques, used for everything from residential homes and retaining walls to commercial buildings and monuments. If you searched for “mansory,” you were likely looking for this term.
Common Masonry Materials
The defining feature of masonry is that it assembles a wall or structure from small, manageable units rather than pouring a single material into a form. The most widely used materials include fired clay bricks, concrete blocks (sometimes called cinder blocks or CMUs), and natural stone like granite, limestone, and marble. Less common options include glass blocks, adobe (sun-dried earth bricks), and cast stone, which is a manufactured product designed to look like natural stone.
Each material brings different properties. Clay brick is prized for its color range and weather resistance. Concrete block is cheaper and faster to lay, making it the standard choice for foundation walls and large commercial projects. Natural stone costs more and takes longer to install but offers unmatched aesthetics and longevity.
How Mortar Holds It All Together
Mortar is the paste applied between masonry units. It bonds the units, cushions them against uneven surfaces, and seals joints against water. Not all mortar is the same. The industry classifies it into four main types, each suited to different situations:
- Type N: A general all-purpose mortar with good bonding and workability. It is the standard choice for above-grade exterior walls, chimneys, parapets, and interior load-bearing walls.
- Type S: Offers higher compressive and flexural bond strength than Type N. It works well for reinforced or load-bearing exterior walls and serves as an alternate in most above-grade applications.
- Type M: The highest compressive strength of the group, recommended for foundation walls, retaining walls, sewers, and anything at or below grade where the masonry contacts soil or groundwater. It is less workable, so masons typically reserve it for heavy-duty applications.
- Type O: A low-strength mortar used mostly for interior partitions and for repointing historic buildings where a softer mortar protects older, more fragile units.
Choosing the wrong mortar type can lead to cracking or premature failure, so the selection is usually specified by an engineer or architect based on the wall’s location and the loads it will carry.
Load-Bearing Masonry vs. Veneer
One of the most important distinctions in masonry construction is whether the masonry itself holds up the building or simply covers the outside of it.
Load-bearing (or solid) masonry walls are structural. They carry the weight of the roof, floors, and everything above them down to the foundation. Traditional solid masonry walls are typically 8 inches thick or more and consist of multiple layers of brick or block (called “wythes”). This was the standard way to build before steel and concrete framing became widespread.
Brick veneer, by contrast, is a single layer of brick attached to the outside of a building whose real structure is wood framing, steel studs, or concrete. The veneer adds weather protection and curb appeal but supports only its own weight. It is fastened to the structural wall behind it using metal anchors, with an air gap of about an inch between the brick and the backup wall. The type of anchor depends on the backup material: corrugated sheet metal anchors work for wood framing with a narrow air space, while adjustable anchors are required for steel or concrete backups because those materials can shift slightly under load.
Most modern houses with brick exteriors use veneer, not solid masonry. If you can see only one layer of brick from the outside and the interior walls are framed with wood studs, it is almost certainly veneer.
Bonding Patterns and Structural Strength
The way bricks overlap from one row (or “course”) to the next affects both appearance and strength. The most common layout is the running bond, where each brick is offset by half its length from the brick below. This staggering distributes loads across the wall and prevents vertical crack lines from forming.
A stack bond places each brick directly on top of the one below, creating a clean grid pattern that many architects prefer for its modern look. However, that alignment creates vertical planes of weakness. Testing on reinforced concrete block walls found that stack pattern walls have 8% to 11% lower bending capacity than equivalent running bond walls. Building codes in the United States impose additional design restrictions on load-bearing stack bond walls for this reason.
Decorative patterns like Flemish bond (alternating the long face and short end of a brick in each course) and English bond (alternating entire courses of long faces and short ends) were historically used in solid masonry to tie multiple wythes together. Today, they appear mainly as aesthetic choices on veneer walls.
Fire Resistance
Masonry is inherently fire-resistant because its raw materials, clay,ite, and concrete, do not burn. Fire resistance is rated in hours, representing how long a wall can withstand a standardized fire test before failing. The rating depends on wall thickness and material type:
- Solid clay brick: A wall just 2.7 inches thick achieves a 1-hour fire rating. At 6 inches, it reaches 4 hours.
- Hollow brick (unfilled): Slightly thinner walls achieve the same ratings because trapped air acts as an insulator. A 2.3-inch wall earns 1 hour; 5 inches earns 4 hours.
- Hollow brick filled with insulating material (such as perlite or vermiculite): Requires somewhat more thickness, around 3 inches for 1 hour and 6.6 inches for 4 hours, because the fill adds mass but less insulation than air.
A 4-hour rating is the highest commonly required by building codes and is typically reserved for firewalls between buildings or around critical stairwells. Standard residential masonry walls easily meet or exceed the 1- to 2-hour ratings most codes demand.
Efflorescence: The White Staining Problem
If you have ever seen white, powdery streaks on a brick wall, that is efflorescence. It happens when water moves through the masonry, dissolves soluble salts inside the mortar or units, and carries them to the surface. Once the water evaporates, the salts crystallize into a visible white deposit. The salts involved are primarily sodium sulfate and potassium sulfate.
The main source of these salts is the Portland cement used in mortar and grout. Specifying low-alkali Portland cement (containing 0.6% alkali or less by weight) often eliminates the problem. Contaminated sand and impure mixing water can also contribute, so clean, washed sand and potable water are important during construction.
Modern clay bricks are manufactured with chemical additives that lock sulfates in place so they cannot dissolve and migrate. On the design side, overhanging eaves, proper copings, and good flashing details keep water out of the wall in the first place. Masons also reduce water infiltration by using tooled, compressed mortar joints, specifically concave or V-shaped profiles, which are denser and more water-resistant than flat or raked joints.
Efflorescence is mostly a cosmetic issue and can usually be cleaned with a stiff brush and water. Persistent cases may need a mild acid wash. Preventing it comes down to controlling moisture and using quality materials from the start.
Building Codes Governing Masonry
In the United States, masonry design and construction are governed by TMS 402/602, published by The Masonry Society. TMS 402 covers structural design requirements, while TMS 602 sets minimum construction standards for the actual masonry work. The current edition, TMS 402/602-22, is referenced by the 2024 International Building Code (IBC), which most U.S. jurisdictions adopt as the basis of their local building regulations. This means any permitted masonry project in the U.S. must comply with these standards, covering everything from minimum wall thickness and reinforcement spacing to inspection and testing requirements.