Engineering Bricks: Everything You Need To Know

What is an Engineering Brick?

An engineering brick is a type of clay brick made to improve the structural properties of a building. They are strong, durable, and resistant to frost and damp. These bricks come in two varieties, class A and class B, have a smooth texture, and contain holes that run from top to bottom.

You can identify an engineering brick by its smooth texture and uniform appearance. Engineering bricks are usually either red or blue but do come in other colours. A standard engineering brick typically measures 215mm x 102.5mm x 65mm.

Class B bricks are sometimes referred to as semi-engineered bricks, as they are not as strong as Class A.

What Are Engineering Bricks Used For?

Engineering bricks are used for construction projects in extreme conditions where durability and strength are key. They are commonly used for building foundations, damp proof courses, retaining walls, tunnels, manholes, and sewers.

Unlike facing bricks, they are not used for decorative purposes, which is why there are fewer variations in style.

How Much Does an Engineering Brick Weigh?

Class A and Class B engineering bricks weigh between 1.95kg and 3.30kg. The below table shows the exact weight for a range of different bricks:

Brick TypeBrick ClassBrick DimensionsBrick Weight
Weinerberger Solid BlueClass A215mm x 102.5mm x 65mm3.28 kg
Ketley Red SolidClass A215mm x 102.5mm x 65mm3.30 kg
Wienerberger TercaClass B215mm x 102.5mm x 65mm1.95 kg
Wienerberger Red SmoothClass B215mm x 102.5mm x 73mm2.55 kg
Wienerberger Terca Solid BlueClass B215mm x 102.5mm x 65mm3.22 kg
Wienerberger Red SolidClass B215mm x 102.5mm x 65mm3.20 kg
Wienerberger Terca Blue PerforatedClass B215mm x 102.5mm x 65mm2.60 kg

The weight of the brick will often depend on whether or not it is perforated or solid. Class A engineering bricks have a density of around 2360 kg/m3 while Class B have a density of 1360 kg/m3.

How Strong Are Engineering Bricks?

Class A are the strongest engineering bricks and have a compressive strength greater than 125N/mm² and water absorption of less than 4.5%. However, Class B are more commonly used and have a compressive strength greater than 75N/mm² and water absorption of less than 7%.

Engineering bricks are significantly stronger than regular facing bricks, which can have compressive strength as low as 12N/mm².

Are Engineering Bricks Damp Proof?

Engineering bricks are not entirely damp proof but are much less porous than regular bricks. Class A engineering bricks have a water absorption of less than 4.5% whereas facing bricks can have an absorption rate as high as 15%.

This low absorption rate and non-porous properties are why engineering bricks are often used for structures that will be exposed to harsh elements. It also means they are less likely to be affected by spalling and efflorescence.

Why Do Engineering Bricks Have Holes?

There are four reasons for the holes in engineering bricks:

1. Stronger Bond

The first, and most important reason, is that they create a better bond by allowing the mortar to flow to the brick below, locking them together. This creates a more structurally sound building.

2. Saves Materials

By reducing the volume of the brick, fewer raw materials are needed to create the finished products. This is good for the environment and will also save the manufacturer money.

3. Reduces Weight

Fewer materials mean the bricks weigh less than if they were solid. This makes it easier and less costly to transport them to construction sites or resellers.

4. Even Heat Distribution

Bricks are made in a kiln under extreme temperatures. The holes allow the heat to penetrate the inside of the brick, not just the external surface area, which results in a more consistent finish. It also speeds up the process, saving fuel by running the kiln for a shorter period of time.

How Much is an Engineering Brick?

On average Class A engineering bricks cost £2.55 each and Class B bricks cost £2.35 each. This works about at £1020 per pack of 400 and £940 per pack of 400, respectively. These costs are based on average retail prices from builders merchants and include VAT.

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