fired clay brick

Environmental Impact Rating

Harvesting — Low to moderate

The clay that forms the bulk of the material in a brick is an abundant resource, with useful deposits in many regions of North America. Clay pits are usually shallow, surface-based harvesting operations that do not use any chemical processes on-site. Disruption to flora and fauna in the immediate region of the pit will be palpable. Many clay pits are in or beside waterways, and pit operations can cause silting of the water and disruptions to flow patterns. In general, clay pits are not considered high-impact mining operations, and are excellent candidates for rehabilitation at the end of their lifespans.

Manufacturing — High

Clay for bricks requires some mechanical processing. It is ground up and squeezed into a homogeneous mix before being formed. This work is typically all completed by machine in factories, though traditionally it would have been done by hand on or near the building site. The largest impact comes from the firing process, during which the bricks are heated to temperatures of 900 to 1300 °C (1650 to 2350 °F) for several hours. No toxins are released from the clay during this process, but a lot of fossil fuels are consumed and emissions released into the atmosphere, including sulfur dioxide.

Bricks that are glazed or painted will require additional processes, and these can be more toxic. Paint coatings, in particular, can contain chemicals that are emitted into the atmosphere and/or mixed into water at the factory.

The mortar used between bricks is a significant amount of material. If a cement-based mortar is used, it carries a high carbon footprint. Lime-based mortars have a lower carbon footprint.

Transportation — Low to High

Sample building uses 26,192 kg of brick siding for the exterior:

24.6 MJ per km by 35 ton truck

6.55 MJ per km by rail

Production facilities are typically very close to clay pits, minimizing the transportation of raw materials. Regional manufacturers are close to many major markets, but if this heavy material has to travel long distances it will accumulate high transportation impacts.

Installation — Negligible

Waste: Low

Compostable — Clay brick offcuts can be left in the environment or used as aggregate or growing medium. Quantities should be low, as partial bricks can be used throughout the wall.

Recyclable — None.

Landfill — Mortar bags.

Chart of Embodied energy & carbon

Energy Efficiency

Brick cladding will not have much impact on energy efficiency. As a rainscreen, it can reduce the amount of wind that reaches the wall behind, but will not contribute to air tightness. Bricks add little to no thermal resistance.

Bricks can be used to create thermal mass inside a building. This will not improve energy efficiency, but may help to modulate temperature swings inside the building, improving comfort. Brick walls are sometimes used as part of a hydronic heating system.

Material costs: high

Labour Input: High

Laying brick is very labor-intensive. Each unit is relatively small and requires careful mortar joints on all sides. The material is heavy; mortar is prepared in small batches and must be kept fresh. Brick ties, weepers and headers over windows all add to the labor input. If patterns and/or arches are included in the design, labor input rises further.

Health Warnings

Mortar mixing can cause exposure to high quantities of silica dust, so proper breathing protection is required.

Skill level required for homeowners

Preparation of substrate — Easy

Wall framing and sheathing skills are required. The process of measuring and fastening brick ties is straightforward.

Installation of sheathing — Moderate to Difficult

There is a lot to learn in order to successfully install brick cladding. Skills required include marking and measuring for brick courses, mortar mixing, laying mortar and brick and creating appropriate headers/arches for openings. Without prior experience or practice, brick laying may best be left to professionals.

Finishing of sheathing — Easy

Jointing between the bricks is the only finish required once bricks are installed.

Sourcing & availability: Easy

Clay bricks are widely available in most regions from masonry supply outlets.

Durability: High

Clay bricks provide a very durable cladding that can last for at least a hundred years, and possibly several centuries. Proper window flashings and an adequate protection from roof splashback will help ensure long life. Bricks that repeatedly absorb a lot of moisture and then freeze (the freeze-thaw cycle) will deteriorate within a decade.

Interior applications of clay brick will be extremely durable.

Code compliance

Acceptable solution in all codes. Be sure to follow local codes for specific requirements.

Indoor air quality: n/a

No effect as an exterior cladding.

Interior brick walls should not have a negative impact on IAQ. If using recycled brick, be sure to assess the origin of the brick before using them indoors as they may have been used on a building or in a location where the porous clay may have absorbed toxic materials (e.g., old chimney brick, kiln brick or industrial brick).

Resources for further research

BDA Guide to Successful Brickwork, 3rd Edition. London: Arnold, 2000. Print.

Hendry, A. W., and F. M. Khalaf. Masonry Wall Construction. London: Spon, 2001. Print.

Kelsey, John. Masonry: The DIY Guide to Working with Concrete, Brick, Block, and Stone. East Petersburg, PA: Fox Chapel, 2012. Print.

Future development

It is unlikely that techniques or materials for brick manufacturing will change dramatically. Brick has a long history in building, and will likely continue to have a reasonable portion of the cladding market. Brick is widely perceived to be an “upscale” cladding, used to distinguish a quality home from a cheap home. Rising costs for brick and masons may cause the market to shrink.