Choosing the right brick for a project comes down to three things: how it performs, how long it lasts, and how it looks. Get any one of those wrong and the consequences show up in the fabric of the building for decades.
This guide covers what specifiers and architects need to know about how to choose architectural bricks – from the manufacturing process and clay sourcing through to water absorption rates, brick colour, surface finish and mortar joint compatibility.
What makes a brick "high performance"?
Not all bricks are built the same. A standard brick pressed from inconsistent clay and fired at the wrong temperature will fail well before its warranted life.
High-performance bricks are defined by their resistance to freeze-thaw cycles, low water absorption, consistent compressive strength and a manufacturing process that controls all of these variables precisely.
In the UK, bricks are classified under BS EN 771-1, which sets out requirements for clay bricks including declared values for compressive strength, water absorption and active soluble salt content. Specifiers should always ask for a Declaration of Performance (DoP) document from the manufacturer before confirming a product on a project.
Understanding the different types of bricks
Knowing the difference between brick types is the starting point for every specification. Each category has a distinct purpose, manufacturing process and performance profile.
Facing bricks
Facing bricks are the most visible element of a brick wall. They are made specifically for their visual appeal and their ability to withstand weather conditions on the external face of a building. Quality facing bricks offer various textures – from smooth, wire-cut surfaces to hand-thrown ,rustic or sand-faced finishes – and a wide range of brick colour options. The aesthetic appeal of a facing brick is as important as its structural contribution.
Engineering bricks
Engineering bricks are dense, low-absorption bricks used where high strength and resistance to water and frost are priorities. Class A engineering bricks have water absorption below 4.5% and compressive strength above 125 N/mm². Class B sits at below 7% and above 75 N/mm². They area common choice for below-ground work, retaining walls, sewers and any situation where the brick structure must handle sustained moisture exposure.
Common bricks and standard bricks
Common bricks are general-purpose building material intended for internal use or areas that will be rendered or plastered. They lack the consistent colour and finish of facing bricks but serve a structural role adequately. Standard bricks refer to the typical UK format: 215mm x102.5mm x 65mm. This standard size is compatible with most construction techniques and mortar joint specifications across modern construction.
Thin brick and brick slips
Thin brick units (typically 20-25mm deep) are used in cladding systems and internal feature walls. They deliver the visual appeal of solid brickwork at reduced weight and depth – useful in refurbishment or where a steel or concrete frame is already in place. Performance depends heavily on the fixing system and adhesive, and specifiers should ensure slip products carry independent test data for their intended application.
Clay sourcing and the manufacturing process
The raw material determines much of the final product. Clay bricks are formed from naturally occurring clay and shale, shaped (extruded, pressed or hand-moulded), dried and fired in kilns at high temperatures – typically between 900°C and 1,200°C. The firing temperature directly affects density, colour and water absorption. Higher firing generally produces a denser, harder, darker brick.
Different clay deposits across Europe produce fundamentally different aesthetic outcomes. Danish brick manufacturer Randers Tegl, exclusively available in the UK through UKBrick, sources from specific Nordic clay deposits that produce a distinctive depth of colour and texture.
The controlled brick manufacturing environment at facilities like Randers Tegl means dimensional tolerances are tight, soluble salt content is consistently low and the uniform appearance of each batch is predictable, reducing waste and variation on site.
How to evaluate brick colour and finish
Brick colour is one of the most contested decisions in any project. Colour varies between batches, between firing positions in the kiln, and between wet and dry conditions. Specifiers should:
Brick surface finish affects far more than aesthetics. A smooth, wire-cut face sheds water quickly and is easier to clean. A rough or textured surface offers more shadow play and visual depth but can retain dirt in urban environments. Sand-faced finishes sit between the two extremes, offering a softer aesthetic with reasonable weather performance.
Mortar joints and design flexibility
The mortar joint is often underestimated in specification.It makes up roughly 17% of a brick wall's visible surface. Mortar joint colour, profile and depth all affect the finished appearance significantly. A flush or recessed joint reads very differently to a struck or ironed finish,even with identical bricks.
Design flexibility increases when specifiers consider brick and mortar as a system. Some of the most successful contemporary brick buildings use contrasting mortar colours to emphasise the horizontal banding of the bond pattern, or deep-raked joints to exaggerate shadow and texture.
Performance in real-world conditions
British weather puts brick through a hard test. Freeze-thaw cycling, driving rain, pollution and thermal movement all affect long-term performance. A brick that passes laboratory testing but fails to stand the test of time in practice reflects poor material selection.
Specifiers should look for:
Harsh weather conditions in the UK, particularly in coastal, upland or northern locations, demand facing bricks with water absorption below 7% and freeze-thaw classification of F2. Using an F1-rated brick in a fully exposed condition is one of the most common specification errors.
Choosing the right brick for your construction project
There is no universal answer to how to choose architectural bricks, but there is a reliable process. Start with the performance requirements of the location: exposure zone, load-bearing role,below or above ground. Then move to aesthetics: architectural style,colour palette, texture and bond pattern. Finally, cross-reference supplier technical data, request samples and confirm compliance with BS EN 771-1.
UK Brick works directly with architects and specifiers throughout this process, providing technical support, sample coordination and access to the full Randers Tegl range alongside a curated selection of facing bricks suited to the demands of modern UK construction.
Specify with confidence
Getting brick specification right from the start saves time,reduces risk and produces better buildings. Whether you are narrowing down a shortlist, working through technical data or looking for a product that meets a specific performance and aesthetic brief, UK Brick's team is here to help.
Request samples, discuss your project or explore the full range of high-performance facing bricks – including the exclusive Randers Tegl collection – Contact us today.
Frequently asked questions
What is the difference between facing bricks and engineering bricks?
Facing bricks are selected for their visual appeal and weather resistance on exposed surfaces. Engineering bricks are chosen for high compressive strength and very low water absorption in structural or below-ground applications.
What does F2 mean on a brick specification?
F2 indicates the highest freeze-thaw durability classification under BS EN 771-1, suitable for fully exposed locations including parapets, retaining walls and external paving.
How many brick types are there?
The main categories are facing bricks, engineering bricks,common bricks and thin brick or brick slips. Within each category there are significant variations in clay type, firing method, texture and size.
What brick size is standard in the UK?
The standard UK brick size is 215mm x 102.5mm x 65mm,producing a 75mm course height when laid with a 10mm mortar joint.