Brick Quality: How To Test It | Travis Perkins

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What are qualities of a good brick?

Good bricks are made using diligent manufacturing processes plus top quality materials, and can vary in strength and visual attractiveness for different uses. High quality bricks have little to no visible defects, offering a consistent shape, size and colour. Brick quality tests assess whether they’re durable, waterproof, free from salts and offer sound-proofing qualities.

The overall brick quality is crucial in construction, and it’s essential to use the right brick type for the job. The most attractive-looking bricks won’t necessarily be the strongest or best bricks for the job. Depending on both the budget and what the bricks are used for, it’s important to choose a high-quality brick or block for the right task, for lasting and durable results.

An in-depth brickwork checklist can help you to examine:

• Physical Characteristics - it’s important to inspect the size, colour, shape and texture to assess brick quality. The presence of soluble salts and/or chemicals can affect performance, and for facing bricks you’ll want them to look their best.

• Mechanical properties - as well as appearance, brick quality is shown through compressive strength, tensile strength, waterproof ratio, abrasion resistance and sound-proofing ability. These strength and durability tests are essential for creating the best quality structure.

Brick quality control measures

There are several different brick types commonly used in construction, each offering different quality levels and characteristics, including:

• Burnt clay bricks - also known as common bricks, these are used in general construction work and are divided into first, second, third or fourth class, demonstrating high (1st) to low (4th) quality.

• Sand lime bricks - also known as calcium silicate bricks, these offer good strength quality and are ideal for using decoratively.

• Sun dried bricks - also known as unburnt bricks, these clay bricks are usually attractive in appearance but lack strength, so they’re often used for temporary structures.

• Concrete bricks - made using cement, sand and aggregates, these offer strength and durability and can come in a wide range of sizes, but aren’t generally popular for exterior decoration.

• Engineering bricks - provide exceptional load-bearing capacity and are characterised by a smooth finish and holes running through the brick.

• Fly ash bricks - made from coal furnace waste products, such as fly ash, and mixed with clay, these are lightweight but offer high thermal conductivity - making them less commonly used in the UK.

Different brick types are manufactured and finished in different ways, which can affect their overall quality, appearance and durability. During a visual inspection, high quality bricks should:

• Be free from cracks, chips and bubbling - this weakens bricks’ structure

• Not contain stones or other debris - this can lead to cracking which will need to be repaired to avoid structural damage

• Not be under-burnt or over-burnt - under-burning or over-burning bricks during the firing process means they’re less durable

• Have clear, defined edges and shapes - this gives an attractive appearance and are easier to lay accurately

• Be of a uniform size, colour and shape - odd shapes and shades lead to a lower quality classification

• Not contain potassium nitrate - this potentially hazardous chemical can damage bricks and cause saltpetre damage, which encourages dampness and associated problems

• Be free from lime pitting and soluble salts during manufacturing - alkali salts cause brick efflorescence, which can lead to dampness

• Be waterproof and strong - and able to withstand weathering for many years

Bricks go through a brick quality test before being sold in the UK. BS EN 771 is the British standard for characterising masonry units. It outlines the testing requirements for classifying brick quality, water absorption and compressive strength, as well as standardising the measurements, properties and appearance of clay bricks, concrete blocks and other engineering bricks.

Testing procedures to measure quality of the bricks

Different brick types are usually broken down into three main categories - facing bricks, engineering bricks and common bricks. Each has their own benefits of cost vs strength ratio, depending on what they’re needed for. The overall brick quality control and durability can be tested using several methods:

Compression test

The compression test in brick quality control shows the load-carrying capacity when the bricks are compressed, using a special compression testing machine. Load bearing walls will need bricks with a higher compressive strength, and different brick types perform differently. A first class brick should have a minimum compressive strength of 10N/mm2. The presence of flaws or salts in the brick can affect the results.

Water absorption test

This shows the total amount of moisture that the brick absorbs when soaked in cold water for 24 hours. This shows how durable an exterior-facing brick will be to weathering and moisture damage. First class bricks should have a result between 12% to 20%. Again, flaws in the brick itself and soluble salts can affect the water absorption rate.

Efflorescence test

The efflorescence test checks the alkalinity of the brick. It looks for the white crystal-like appearance on the surfaces, which can be caused by dampness or the presence of soluble salts. Not only does this look unsightly, there could be a risk of dampness later on. Ideally, first class bricks will have a degree of efflorescence rated as NIL – meaning no perceptible deposit of efflorescence.

Bricks may also be assessed for soundproofing ability, flammability, thermal insulation and thermal conductivity. It’s important to note that using very wet or very dry bricks may affect brick quality test results and the overall quality control process.

Brickwork quality control checklist 

The manufacturer will be able to provide data from their quality control tests, but your own brick quality inspection on site is essential too. Your brickwork quality control checklist should include:

• A visual Inspection - look for signs of damage, inconsistent colour and non-uniform appearance. Any presence of debris or efflorescence means a lower quality brick.

• Measurement checks - it’s vital that brick dimensions are checked to give consistent results. Bricks should be neatly stacked and/or measured in size, weight, shape and alignment.

• Mortar analysis - using the correct mortar ratio is key to a quality finish. Excess or uneven mortar reduces the overall quality of the brickwork.

Quick tips on how to check brick quality 

As part of your brickwork quality control checklist, you may wish to carry out your own DIY brick quality assessment. Here are four ways of testing:

• Brick crack test - each brick should be checked to see if it’s smooth in texture and have no obvious chips, cracks or a bubbling texture. Ideally they should be neatly stacked or measured to check that they are all the same shape and size.

• Brick clap test - if you clap two bricks together they shouldn’t break, crack or crumble easily, as they should be strong enough for minor impacts, and should make a clinking sound as they meet.

• Brick drop test - by dropping the brick from a height of around 1.5 m, it wouldn’t usually break if the brick quality is good and it’s strong and sturdy. 

• Brick water weight test - good quality bricks should not take on too much water, or change shape or size when wet. Weigh a dry brick, soak in cold water for 24 hours, then weigh again. Better quality bricks increase no more than 15% in weight.

Brick quality: FAQs

What is good quality brickwork?

Good quality brickwork should be even, straight, plumb and not leaning, with little excess mortar visible. It shouldn’t have obvious staining, chipping, air bubbling or cracking, and ideally be a uniform shade and size throughout.

How can you tell the quality of brick?

Top quality bricks have a low water absorption rate, making them durable and longer lasting. Bricks should be properly fired, and made using high quality clay that’s free from stones or chemicals which may weaken the structure. Each brick should have a smooth surface, and be of a consistent colour, size and appearance.

What are high quality bricks?

The best quality bricks are known as first class bricks. These are usually burnt clay facing bricks, which are strong, smooth and attractive looking with well-defined edges. Second class bricks, or engineering bricks, are characteristically strong but lack the even look of first class bricks.

In summary, there are several tests to assess brick quality, from on-site visual inspections to strength and waterproof testing provided by the manufacturer. If you’re unsure which bricks are best for the task, your local Travis Perkins branch can help to advise you. 

For cold weather brick laying advice, to a glossary of bricklaying terms and our brick calculator - plus the latest industry news, advice and inspiration - visit the Travis Perkins Trade Hub.

Disclaimer: Information displayed in this article is correct at the time of publication, but note that legislation changes periodically. The information contained on this page is intended as an overall introduction and is not intended as advice from a professional building control officer. Travis Perkins aims to avoid, but accepts no liability, in the case that any information stated is out of date.