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At ET Clay Products, we frequently receive enquiries from customers regarding weathered bricks. There are many reasons why a client will need bricks that have a weathered appearance. Probably the most obvious reason for wanting weathered bricks will be for an extension to an existing brick built building.

If a building has been standing for a number of years, the bricks will clearly have been exposed to the elements and everything it has to throw at the them. It stands to reason that if an extension is built onto a 30 year old property, and that extension is constructed from brand new, unweathered bricks, the end result will look very odd indeed.

ET Clay Products has the solution

This doesn't mean to say that you have to search the length and breadth of the countries reclamation yards for an exactly matching 30 year old brick of the same type, because ET Clay Products stock more than their fair share of weathered brick styles. This takes the hassle out of searching in vain for a match. Just use our brick matching service to discover just how closely you can match our bricks to your existing ones.

Maybe you just need a few bricks for a smaller building project! For example, you may wish to put windows where a patio door was, or install a lower window thus needing some bricks to fill the gap. There is nothing worse than seeing an obvious mismatch of bricks beneath or above a window, which is why we supply so many types and styles of weathered brick finishes.

What is brick weathering?

Weathering refers to the process by which bricks or anything else are effectively broken down over time. Anything that is left exposed to the elements long enough will eventually dissapear altogether. The speed at which weathering occurs depends on the durability of the item in question. Bricks may be pretty hard wearing building materials, but they are still susceptible to weathering.

Types of weathering

There are three main types of weathering that can affect bricks:

  • Chemical weathering: Chemical weathering will change the composition of the bricks, often transforming them when water interacts with certain minerals to create various chemical reactions. Chemical weathering is a gradual and ongoing process as the mineralogy of the brick adjusts to the near surface environment. New or secondary minerals develop from the original minerals of the brick. In this the processes of oxidation and hydrolysis are most important.
  • Physical weathering: Physical weathering is the process that causes the disintegration of bricks without chemical change. The primary process in physical weathering is abrasion. However, chemical and physical weathering often go hand in hand. Physical weathering can occur due to adverse temperature, pressure or frost. For example, cracks exploited by physical weathering will increase the surface area exposed to chemical action. Also, the chemical action of minerals in cracks can aid the disintegration process in bricks. Physical weathering is also called mechanical weathering or disaggregation.
  • Biological weathering: Biological weathering of bricks is caused by the activities of living organisms. For example, the growth of roots or the burrowing of animals. Tree roots are probably the most often occuring cause, but it can often be by animals, in particular, insects that can burrow away at the sandy texture of the brick.
    Biological weathering of bricks is the actual molecular breakdown of minerals. There are things called lichens which are combinations of fungi and algae, that live on bricks. Lichens slowly eat away at the surface of the bricks. The amount of biological activity that breaks down minerals depends on how much life is in that area. There may well be more lichen activity nearer to coastal areas where the air is more humid and cooler.

It should be noted that brick buildings are mostly susceptible to physical weathering.

Porous bricks

As bricks are naturally porous, it makes it easier for water and other elements to work their way into the brick and break it down over time. Porosity refers to the small holes in the surface of the brick. Generally speaking, the more porous a brick is, the quicker it is likely to break down.

Ice crystallisation in bricks

This is also known as ice wedging and it occurs when water gets into a crack or pore in the brick, and then expands as it freezes. This process results in the brick fracturing and possibly breaking pieces off.

Salt crystallisation in bricks

Salt crystallisation is pretty similar to ice crystallisation. It occurs when a saline solution gets into the pores or cracks in a brick and expands as it crystallises. Salt crystallisation is normally only a problem in coastal areas and in hot, dry environments.

The effect of wind and rain on bricks

Because bricks generally make up the exterior of a building, they are a surface that are exposed to wind and rain. Although no single weather event significantly erodes the brick, the effect of wind and rain over many years will eventually help to break them down. As with other forms of weathering, the speed at which it occurs depends heavily on the porosity of the brick.


t: 01708 200 304

t: 01708 200 304