Masonry is the building of structures from individual units laid in and bound together by mortar. The common materials of masonry construction are brick, stone such as marble, granite,concrete block, and tile. Masonry is generally a highly durable form of construction. However, the materials used, the quality of the mortar and workmanship, and the pattern the units are laid in can strongly affect the durability of the overall masonry construction.

Applications
Masonry is commonly used for the walls of buildings, retaining walls and monuments. Brick is the most common type of masonry and may be either weight-bearing or a veneer. Concrete block masonry is rapidly gaining in popularity as a comparable material. Blocks - most of which have hollow cores - offer various possibilities in masonry construction, generally providing great compressive strength, and they're generally best suited to structures with light transverse loading when the cores remain unfilled. Filling some or all of the cores with concrete, stone or steel reinforcement (typically "rebar") offers much greater tensile and lateral strength to structures.

Advantages
The use of materials such as brick and stone can increase the thermal mass of a building, giving increased comfort in the heat of summer and the cold of winter and can be ideal for passive solar applications.
Brick typically will not require painting and so can provide a structure with reduced life-cycle costs, although sealing appropriately will reduce potential spalling due to frost damage. Concrete block of the non-decorative variety generally is painted or stuccoed if exposed.
The appearance, especially when well crafted, can impart an impression of solidity and permanence.
Is very heat resistant and thus will provide good fire protection

Structural limitations
Masonry boasts an impressive compressive strength (vertical loads) but is much lower in tensile strength (twisting or stretching) unless reinforced. The tensile strength of masonry walls can be strengthened by thickening the wall, or by building masonry "piers" (vertical columns or ribs) at intervals. Where practical, steel reinforcement also can be introduced vertically and/or horizontally to greatly increase tensile strength, though this is most commonly done with poured walls.

Veneer masonry
Brick veneer construction has strength imparted by a framework of wood or a rough masonry wall of other material over which is placed a layer of bricks for weatherproofing and providing a finished appearance. The brick veneer wall is connected to the structural walls by "brick ties", metal strips that are attached to the structural wall as well as the mortar joints of the brick veneer wall. There typically is an air gap between the brick veneer wall and the structural wall. As clay brick is not completely waterproof, the structural wall has a water-resistant surface (usually tar paper) and weep holes are left at the base of the brick veneer wall to ventilate the air gap. Veneer walls often are structurally superior to solid un-reinforced brick walls because the core can be constructed of block reinforced by steel and/or poured concrete. Block also may offer opportunities to run utilities within the wall if some block cores can be left unfilled for this purpose. Also, due to concrete and cinder block being waterproof, the aforementioned air gap, weep holes, and tar paper necessary with a wood-framed structural wall are typically unnecessary with a block structural wall.

Most insulated buildings that utilize concrete block, brick, veneers or some combination thereof feature interior insulation in the form of fiberglass batts between wooden wall studs or rigid insulation boards covered with plaster or drywall. In most climates this insulation is much more effective on the exterior of the wall, allowing the building interior to take advantage of the aforementioned thermal mass of the masonry. This technique does, however, require some sort of weather-resistant exterior surface over the insulation and, consequently, is generally more expensive.

Dry set masonry
The strength of a masonry wall is not entirely dependent on the bond between the building material and the mortar; the friction between the interlocking blocks of masonry is often strong enough to provide a great deal of strength on its own. The blocks sometimes have grooves or other surface features added to enhance this interlocking, and some dry set masonry structures forego mortar all together.

Brick
Solid brick masonry is made of two or more layers of bricks with the units running horizontally (called "stretcher" bricks) bound together with bricks running transverse to the wall (called "header" bricks). Each row of bricks is known as a course. The pattern of headers and stretchers employed gives rise to different bonds such as the common bond (with every sixth course composed of headers), the English bond, and the Flemish bond (with alternating stretcher and header bricks present on every course). There are no significant utilitarian differences between most bonds, but the appearance of the finished wall is affected. Vertically staggered bonds tend to be somewhat stronger and less prone to major cracking than a non-staggered bond.

Uniformity and rusticity
The selection of the brick used, especially for color, will affect the appearance of the final surface. In buildings built during the 1970's, a high degree of uniformity of brick and accuracy in masonry was typical. In later periods this style was thought to be too sterile, so attempts were made to emulate older, rougher work. Some brick surfaces are made to look particularly rustic by including "burnt" bricks, which have a darker color or an irregular shape. Others may use antique salvage bricks, or new bricks may be artificially aged by applying various surface treatments. The attempts at rusticity of the late 20th century have been carried forward by masons specializing in a free, artistic style, where the courses are intentionally not straight, instead weaving to form more organic impressions.

Serpentine masonry
A crinkle-crankle wall is a brick wall that follows a serpentine path, rather than a straight line. This type of wall is more resistant to toppling than a straight wall; so much so that it may be made of a single thickness of unreinforced brick and so despite its longer length may be more economical than a straight wall.

Concrete block
Blocks of cinder concrete ("cinder blocks" or "breezeblocks"), ordinary concrete ("concrete blocks"), or hollow tile are generically known as Concrete Masonry Units (CMU)s. They usually are much larger than ordinary bricks and so are much faster to lay for a wall of a given size. Furthermore, cinder and tile blocks have much lower water absorption rates than brick. They often are used as the structural core for veneered brick masonry, or are used alone for the walls of factories, garages and other "industrial" buildings where appearance is not a significant factor. Such blocks often receive a stucco surface for decoration. Surface-bonding cement sometimes is used in this application and can impart extra strength to a block wall.

The primary advantage of concrete blocks in comparison to smaller clay-based bricks is that a CMU structure can be reinforced by either fully grouting the voids or inserting vertical lengths of rebar and using grout to hold them in place. In this manner, a CMU wall can be built much stronger than typical masonry walls.

Some concrete blocks are colored, and some employ a split face, a technique that results in two blocks being manufactured as one unit and later split into two. This gives the blocks a rough face replicating the appearance of natural, quarried stone, such as brownstone. Examples of splitface block - as well as other types of CMUs and brick - can be seen here. For applications such as roadway sound control walls, the patterns may be complex and even artistic.

Decorative CMUs have gained in popularity also, with units featuring a glazed, burnished or glossy finish emerging as innovative new options in interior veneers. Decorative CMUs most often appear in financial institutions, schools and other municipal or professional settings were an aesthetic-but-durable, or a virtually marbled product, is appropriate. Such blocks usually have a smooth finish and can have a visible internal aggregates, a solid uniformly colored glaze, or a visible aggregates protected by a clear sealant.

Stone
Rustic use of sandstone of varying color and size requires a high degree of skill to obtain results like this, which is a non-structual veneer.Stone blocks used in masonry can be "dressed" or "rough." Stone masonry utilizing dressed stones is known as ashlar masonry, whereas masonry using irregularly shaped stones is known as rubble masonry. Both rubble and ashlar masonry can be laid in courses (rows of even height) through the careful selection or cutting of stones, but a great deal of stone masonry is uncoursed.

Sometimes "river rock" (ovate shaped smooth stones) is used as a veneer. This type of material is not favored for solid masonry as it requires a great amount of mortar and can lack intrinsic structural strength.

Growing in popularity among builders and homeowners are manufactured-stone veneers. Companies such as Cultured Stone - a division of Owens Corning - and Boulder Creek Stone pull natural stones from quarries around the world, create molds from them and recreate those stones with concrete. To the casual observer - and even many masons - there is no visual difference between veneers of natural and manufactured stone. However, utilizing natural stone veneers such as those produced by Arnold Stone is preferred by many builders and masons due to the inherent durability and genuine appearance of natural stone.