Common Brick: A Classification

The construction market greets us with such an abundance of wall materials that sometimes you don't know whom to ask or how to make sense of everything on offer. Here we classify the traditional building brick, which, despite being several thousand years "old," has not lost its popularity as a reliable, durable, weatherproof material. What does the average person know about it? Most people only tell red brick from white, but there are more kinds of this stone, and they differ not only in color but also in shape, size, raw-material composition, and production technology. So, what does one need to know about brick?

First of all, we should understand that in modern construction there are two kingdoms — common brick and facing brick.

Common brick is used to build the body of the wall, while facing brick is used to finish the outer surface of the wall. We classify facing brick separately. Below we discuss only common brick.

Let's look at the brick characteristics that matter for laying walls, where the brick is not visible from the outside.

Brick is a building material — a small artificial stone of regular shape.

Brick is a building material, a small artificial stone of regular shape. This is a standard building material (it goes by many names — standard brick, wall brick, red brick, clay brick, or common brick) that is used to build walls and, more rarely, foundations. It is not required to have high aesthetic qualities, so cracks and chips are not a sign of poor-quality stone. Modern suburban construction has adopted multilayer wall construction, so common brick is often hidden under insulation and finishing.

Types of brick by material

Common ceramic brick

Made from clay (sometimes a blend of different clays), it goes through high-temperature firing (about 1000 °C) after molding and drying. This is the most recognizable red brick. Quality stone has a rough, matte surface, produces a characteristic ringing sound when struck, and is porous, uniform, and lightweight at the break.

Common ceramic clinker brick

It is theoretically possible to use clinker brick as common brick. But clinker brick is usually brought from far away, it requires special high-temperature clay and increased energy consumption for firing, and it is therefore expensive without offering significant benefits for building walls. For that reason it is produced and used mainly as facing brick.

Common silicate brick

Made from a mixture of sand and lime (90% quartz sand and 10% air-slaked lime), it is steam-cured in an autoclave instead of being fired. It is usually recognized by its white color, but on request it can be made with an added color pigment for use as facing brick.

The main advantage is the low price. It has a slightly lower thermal conductivity than ceramic brick, but even so this brick is not "warm" enough for a modern cottage. Its drawbacks are high hygroscopicity (it absorbs water), low frost resistance (F50), and greater weight.

Silicate brick is not as versatile as ceramic brick; it cannot be used in foundations and basements, or in fireplaces, ovens, and other critical structures.

Common concrete brick

Vibropressed and hyperpressed — the difference is the pressure applied during manufacture. It is rarely used to build house walls. Produced from cement, it is very heavy, cold, and expensive. Brick made of high-strength concrete grades can be used in places with heavy loads. Such brick often contains salts, which when wet can seep onto the facade as white efflorescence.

Refractory brick

Refractory brick is designed for lining ovens and fireplaces. There are grades of ceramic brick for laying stoves. A more specialized type, meant for the hottest part of the furnace, is fireclay brick. It is easily recognized by its characteristic sandy color. It resists intense heat and can withstand temperatures up to 1650 °C.

Size and weight of common brick

The most common sizes, which can be called standard:

• Single brick (single row) — 250 x 120 x 65 mm, weight 2-2.3 kg
• One-and-a-half brick (thickened) — 250 x 120 x 88 mm, weight 3-3.2 kg
• Double brick (2NF) — 250 x 120 x 138 mm, weight 4.8-5 kg

Ceramic stones of larger dimensions are already called building blocks. There are also wedge-shaped bricks for laying radius elements.

The range of facing brick for finishing walls is much wider, but here we consider only common brick.

Brick strength

The most important characteristic of a brick is its strength, that is, its ability to resist deformation and internal stress without breaking. By strength, bricks are divided into grades denoted by the letter "M" with a number: M-50, M-75, M-100, and so on. The number indicates the permissible load in kilograms per square centimeter. The higher the grade number, the stronger the brick.

Brick structure

A solid brick is a brick with no voids (through holes), or with a void fraction of no more than 13%.

Hollow brick (slotted or perforated) has through holes (voids) of various shapes and sizes, which make it lighter and give it greater insulating capacity.

Hollow brick is cheaper to produce. Using hollow common brick lets you reduce the load on the foundation. The difference in thermal conductivity is not very significant when comparing the thermal conductivity of the assembled masonry. Fastening some types of facade trim to slotted brick can be unreliable. Solid brick is better at withstanding loads (both vertical loads and pull-out fasteners).

Frost resistance of brick

A brick's resistance to changes in temperature and humidity is determined by a quality called frost resistance — the material's ability to withstand cycles of thawing and freezing in a water-saturated state. Frost resistance is denoted by the letter "F" with a number and is measured in cycles: F-15, F-35, F-50, and so on.

It is important to understand that in cold climates brick takes on moisture not from the outside but from the inside. In our practice, we see how, combined with improper finishing, brick is actively destroyed by moisture freezing inside it — a serious risk in service.

The frost-resistance grade of brick for construction is chosen according to the regulatory documents, depending on the climatic conditions of the region; the lower the frost-resistance rating, the cheaper the brick. This figure should always be checked before buying the material.

Thermal conductivity of brick

Thermal conductivity is the ability of brick to conduct heat energy through its own volume. Actual thermal conductivity is directly related to the density of the material and inversely related to its voids. For example, heavy, strong M500 clinker brick has the highest thermal conductivity, while less strong M75 ceramic has the lowest.