Brick Matching in London Extensions: How to Match Your Original Brickwork

In most London boroughs, planning conditions require that extension materials — including brickwork — match or complement the original building. For extensions in conservation areas or Article 4 areas, the requirement is stricter: materials must closely match the host building in colour, texture, and bond pattern.

Beyond planning, a poorly matched extension is visually obvious and damages the property's appearance and value. The extension will always look like an addition rather than part of the original house. For properties where the brickwork is a major visual feature — Victorian and Edwardian terraces, for example — the mismatch is particularly jarring.

Before you can match a brick, you need to identify what you have. Victorian and Edwardian London brickwork was produced by dozens of different brickmakers across the region, and the same period produces significant variation in colour, size, and texture.

Key characteristics to note:

- **Colour**: London stock bricks range from pale yellow-grey to deeper buff and brown tones. Red brick (Staffordshire Blues, Flettons) is common in later Victorian and Edwardian construction. - **Size**: Pre-metric bricks are typically 9 inches x 4.5 inches x 3 inches. Metric bricks are 215mm x 102.5mm x 65mm. Many older London stocks are slightly variable in size. - **Texture**: Handmade stocks have a soft, irregular face. Machine-made bricks are more uniform. Wire-cut bricks have a different texture again. - **Bond pattern**: Most Victorian terraces use Flemish bond (alternating headers and stretchers in each course). Some use English bond or stretcher bond. - **Mortar joint colour and profile**: This is often overlooked but critically important. A recessed, slightly lighter mortar joint is typical of Victorian work. Modern flush joints with grey mortar look completely wrong.

The two main approaches to matching are reclaimed bricks and new bricks manufactured to match.

**Reclaimed bricks** are salvaged from demolition sites and are often the best match for Victorian and Edwardian London brickwork — because they are, literally, the same brick. The advantages are authenticity, colour depth, and the slight irregularity that new bricks lack. The disadvantages are variable supply, higher cost, and the need to clean old mortar from the brick face (which affects the final appearance).

Reclaimed London stocks and Kentish stocks can be sourced from architectural salvage yards across London and the South East. Expect to pay £400–£900 per 1,000 bricks depending on quality, cleaning, and demand.

**New bricks to match** are manufactured by several UK producers specifically to replicate common London stock and multi-stock colours. They are more consistent and immediately available, but the match is rarely perfect on delivery — they typically need weathering time to lose the "new" appearance. Major suppliers include Wienerberger, Michelmersh, and Ibstock, all of whom produce London stock ranges.

For conservation area work, councils sometimes require approval of a sample panel of the proposed brick before construction begins.

A sample panel is a small section of brickwork — typically at least 1 square metre — built in the proposed extension location using the proposed brick and mortar mix, bonded in the proposed pattern.

Some planning conditions require formal approval of the sample panel by the planning authority before the main brickwork can proceed. This is standard practice in conservation areas and for listed building work.

Even where not formally required, building a sample panel is good practice on any project where close matching is important. It allows the client, contractor, and planning authority to assess the match before committing to the full quantity. Sample panels should be left in place to weather for 2–4 weeks before final assessment.

Mortar colour and profile are as important as the brick itself. A perfect brick match with the wrong mortar will still look wrong.

Victorian London brickwork typically used lime-based mortar — softer, lighter in colour (often cream or light grey), and with a slightly recessed or weathered joint profile. Modern Portland cement mortar is too hard, too grey, and too flush for traditional brickwork and should never be used to match Victorian construction.

For extensions matching Victorian or Edwardian originals, the mortar should be:

- A lime-based or hydraulic lime mix (NHL 2 or NHL 3.5 for external work) - Coloured to match the original joint (usually buff, cream, or light grey) - Finished with a similar joint profile — slightly recessed, struck, or weather-struck depending on the original

Your contractor should mix and test mortar samples against the original before the main works begin.

Brick matching adds cost to an extension project. Budget for:

- Additional time for sourcing and specification (typically 2–4 weeks for reclaimed bricks with good availability) - Reclaimed brick premium over standard new brick: £200–£500 per 1,000 bricks - Sample panel construction: £300–£600 labour and materials - Planning approval of sample panel if required: adds 4–8 weeks to programme - Lime mortar premium over cement mortar: typically £200–£400 per 100m2 of brickwork

For a typical rear extension with 20m2 of matching brickwork, the total brick-matching premium (reclaimed bricks + lime mortar + sample panel) is typically £1,500–£3,500 over standard new brick construction. For conservation area work requiring formal sample panel approval, allow an additional 6–8 weeks on programme.