Brick Matching: How We Identify the Right Brick for Your Project

Accurate brick matching requires an understanding of clay mineralogy, firing conditions, texture formation, dimensional tolerances and how these variables translate into on-site appearance. A match that looks adequate in a sample tray can behave differently once built, especially when adjacent to older masonry. This guide explains the technical considerations involved in achieving a reliable brick match for extensions, refurbishments and isolated repairs.

Why Brick Matching Matters

Matching is not only an aesthetic requirement. Incorrect matches can create visible discontinuities that negatively affect value, planning approval, and long-term appearance. Texture, firing variation and mortar contrast all influence the final result. When working on properties where coursing must align precisely with existing work, variations in brick height can also affect lintel levels, DPC alignment and structural positioning.

For projects where tie-ins, corner toothings or changes in loading occur, good matching reduces visual disruption and maintains continuity with the original build. For reference, see our facing bricks range where many of the commonly used modern alternatives are sourced.

Colour Variation: Fundamental Causes

Brick colour is driven primarily by clay composition and firing behaviour. Even within a single quarry, the mineral content can shift across seams. Clay seams with higher iron oxide levels darken during firing and can introduce deep reds, browns or purple undertones. Some manufacturing sites deliberately blend clays to achieve a controlled variation, but others extract from wider seam ranges out of operational necessity, producing broader colour spreads.

Kiln Position and Thermal Gradients

In a tunnel kiln, temperature can vary by 40 to 80 degrees between entrance, core and exit zones. Bricks positioned near the outer edges experience slightly different heating and cooling curves. These thermal gradients change the oxidation state of iron compounds in the clay, which shifts the final colour. As a result, even a single batch can contain bricks with noticeable variation when examined in full daylight.

Moisture Content at Time of Comparison

Bricks stored outdoors absorb moisture unevenly. A wet brick temporarily appears darker because the water reduces surface reflectance. This is relevant when matching older walls, which may hold residual moisture in colder months. A brick that appears incorrect in a dry sample tray may be an accurate match once installed and exposed to the same moisture conditions as the existing wall.

For architects specifying exact matches, it is advisable to compare samples under consistent lighting and moisture conditions. Our stock includes a broad selection of brick types for comparison under controlled conditions.

Texture: The Most Visually Critical Component

Texture affects how light interacts with a wall surface. A smooth wirecut brick reflects more light directionally, making small colour differences more visible. A sand-faced or handmade brick scatters light, which softens tonal contrast. Texture mismatches are therefore more noticeable than colour mismatches, particularly when adjoining a wall built with a deep dragface or heavy sand finish.

Machine-made handmade style bricks often lack the irregular arrises and creases found in true hand-pressed products. When placed next to genuine handmade stock, their uniformity becomes apparent. When assessing samples, consider how the existing wall was produced, including whether the bricks were frogged, solid, perforated or wirecut.

Surface Sheen and Light Reflectivity

Some extruded bricks develop a subtle sheen created by high-pressure extrusion or by the fine sands used during manufacture. This sheen can cause reflectivity differences that are most noticeable under low winter sun. Older bricks often have eroded surfaces that produce diffuse reflection. A new brick with even a slight sheen can appear out of place when placed beside aged masonry.

Brick Tolerances and Dimensional Accuracy

Although the nominal UK standard brick size is 215 x 102.5 x 65 mm, compliance with BS EN 771-1 permits dimensional variation. Modern bricks may run a few millimetres taller or shorter depending on the firing shrinkage characteristics of the clay. Older bricks, particularly pre-1970s regional types, can vary significantly across a single elevation.

When matching into existing work, even a 1 mm difference in height per course results in a cumulative variation of 10 mm over ten courses. This disrupts lintel seating heights, window alignment and DPC lines. For extensions requiring accurate structural alignment, this must be accounted for during specification. You can refer to our brick accessories and brick reinforcement ranges when planning structural tie-ins.

Blending on Site

Even with a correct product match, improper blending results in visible banding. Bricks should be drawn simultaneously from multiple packs because each pack may contain a slightly different distribution of tones. Pulling bricks sequentially from a single pack produces horizontal stripes that only become apparent after several courses are laid.

Blending should be checked at intervals by stepping back ten to fifteen metres from the wall. Any localised concentration of darker or lighter tones should be corrected immediately. This is especially important with multi-stock bricks and those produced in wide colour ranges where manufacturer tolerances permit significant variation.

Common Brick Matching Errors

Errors usually come from incomplete assessment methods:

• Comparing samples in indoor lighting, which distorts real colour appearance
• Comparing new bricks to weathered bricks without accounting for surface erosion and pollution staining
• Failing to consider mortar colour, which shifts the perceived tone of an elevation by several percent
• Assuming that all 65 mm bricks are interchangeable without checking height tolerances
• Selecting bricks from mixed stock yards where batches are not segregated

When an Exact Match Is Not Advisable

Some builds benefit from choosing a near-match rather than replicating the existing wall exactly. This applies when existing bricks have undergone significant environmental change, such as acid rain bleaching, frost erosion or industrial staining. Attempting to match a heavily aged appearance using a modern brick often results in a jarring contrast. In these cases, it may be beneficial to use a sympathetic but intentionally distinct brick type, particularly on secondary elevations.

Our Brick Matching Process

Our process involves technical review, on-site considerations and supplier knowledge:

1. Assess brick samples or detailed photographs taken under uniform daylight conditions
2. Identify the probable clay source and manufacturer characteristics
3. Check dimensional tolerances and assess their impact on coursing alignment
4. Match texture, sheen, colour range and firing characteristics
5. Select suitable alternatives from our brick range when exact matches are not workable
6. Provide blending instructions to prevent banding and tonal concentration
7. Arrange prompt supply with the appropriate number of packs for consistent blending

Additional relevant standards: NHBC masonry tolerances.