London Stock Brick Matching for Extensions: Complete Guide
Getting brickwork right is the difference between an extension that blends seamlessly with your existing home and one that looks like an obvious addition. Here is everything you need to know about matching London stock bricks.
Quick Answer
London stock bricks cost £0.80-3.00 per brick depending on whether new or reclaimed. Mortar matching is equally important — wrong mortar colour is the most common brick matching mistake. In conservation areas, planners often require a sample panel before main construction begins.
£0.80-1.50/brick
New stocks
£1.00-3.00/brick
Reclaimed stocks
Often required
Sample panel
Check your specific property constraints
Free Property CheckWhy Brick Matching Matters
Brick matching is one of the most important details in any London extension project. A poor brick match is immediately visible and permanently diminishes the appearance of your home. Conversely, a well-matched extension looks as though it has always been part of the building.
- Planning condition: Many planning permissions include a condition requiring brick matching to be approved before construction begins
- Conservation area requirement: Planners in conservation areas typically insist on exact material matching to preserve the character of the streetscape
- Property value: A seamless brick match protects your property's value and kerb appeal. A visibly mismatched extension can reduce saleability
- Street scene harmony: London's architectural character depends on consistent brickwork. A good match respects the visual unity of the street
What Is London Stock Brick?
London stock bricks are the distinctive yellow-grey clay bricks that define London's architectural character. Made from clay mixed with chalk and ash, they have been manufactured in London and Kent since the Georgian era. Their unique colour comes from the chemical reaction between the clay and the chalk during firing.
The term “stock” originally referred to the wooden mould (stock board) used to form the bricks. Over time, the name became synonymous with the distinctive yellow bricks used to build the majority of London's Victorian and Edwardian housing stock.
London stocks are softer than modern engineering bricks and were designed to be used with lime mortar, which allows moisture to move through the brickwork. This characteristic is important when matching old brickwork, as using the wrong mortar type can cause damage.
Types of London Stock Brick
London stocks are not all the same colour. Variations in clay source, firing temperature, and position in the kiln produce a range of tones. Understanding which type matches your existing brickwork is the first step to a successful match.
Yellow Stocks
The most common type, with a warm yellow-buff colour. These are the bricks that define most Georgian and early Victorian London. The colour ranges from pale straw to warm golden yellow depending on the clay source and firing conditions.
Grey Stocks
A cooler, grey-yellow tone produced by different clay compositions or higher firing temperatures. Common in late Victorian and Edwardian properties. Often found in north and east London where different clay beds were used.
Red Multi-Stocks
Bricks with a mixture of red, orange, and yellow tones. Created by varying clay composition and positioned closer to the heat source in the kiln. Common in late Victorian properties, especially in south London.
Seconds (Rough Stocks)
Irregularly shaped or over-fired bricks that were traditionally used for internal walls or rear elevations. Darker and more varied in colour. Sometimes deliberately sought for character in garden walls and feature elements.
New vs Reclaimed Bricks
The choice between new-manufacture stock bricks and reclaimed originals is one of the most important decisions in your extension project. Each has advantages and limitations.
New Manufacture Stocks
£0.80-1.50 per brick
- Consistent quality and supply
- Guaranteed structural performance
- Available in large quantities
- Lack aged, weathered character
- May not pass conservation area scrutiny
Reclaimed Stocks
£1.00-3.00 per brick
- Authentic weathered appearance
- Best match for conservation areas
- Sustainable (reusing existing materials)
- Limited and variable supply
- Variable quality (frost damage, mortar residue)
Brick Slips: A Third Option
Brick slips are thin facing bricks (20-25mm thick) cut from full bricks or manufactured as slips. They are adhered to a substrate and give the appearance of full brickwork. Cost: £40-80/m² installed.
Suitable for: cladding over insulation on existing walls, internal feature walls, and situations where the full depth of a brick is not structurally needed. Not suitable for structural walls or areas exposed to severe weather.
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How to Match Existing Brickwork
Matching brickwork is both an art and a science. The goal is not to find a brick that matches a single sample but to match the overall character and variation of the existing wall.
- Take a physical sample: Remove a brick from a concealed area (inside a cupboard, behind a downpipe) and take it to your brick merchant. A photograph is not sufficient for colour matching
- Consider mortar colour: The mortar between bricks contributes as much to the overall appearance as the bricks themselves. A perfect brick match with wrong mortar still looks wrong
- Check cleaned vs weathered: Your existing bricks have been weathering for 100+ years. A new brick that matches the cleaned face may look very different once laid. Always compare the weathered face
- Get 3+ samples: Ask your merchant for at least three different options. View them next to your existing wall in both daylight and shade, as brick colour changes significantly with lighting
- Match the variation: London stock brickwork has natural colour variation. A perfectly uniform new brick will look wrong next to the varied tones of 150-year-old brickwork. Select bricks with similar variation
Mortar Matching
Mortar matching is equally as important as brick matching and is the detail most commonly overlooked. Mortar joints make up approximately 15-20% of a wall's visible surface, so the wrong colour or profile is immediately noticeable.
Warning: Wrong Mortar Damages Soft Stock Bricks
Modern Portland cement mortar is too hard for soft London stock bricks. It traps moisture inside the brick, causing the face to spall (break away) during frost cycles. Always use lime mortar (or a lime-dominant mix) with London stock bricks. A standard 4:1 cement mortar will damage your brickwork within 5-10 years.
Key Mortar Matching Points
- Lime mortar vs cement mortar: Original London stock buildings used lime mortar, which is softer than the bricks and allows moisture movement. Always use lime mortar or a weak lime-cement mix (1:1:6 or 1:2:9 cement:lime:sand)
- Colour mixing: Mortar colour comes from the sand, not the cement. Match the sand colour to existing mortar. Yellow, silver, or white sands produce very different results. Brick dust or pigments can fine-tune the colour
- Joint profile matching: Match the existing joint profile exactly. Common profiles include flush, bucket handle (concave), weathered (angled), and recessed. Each creates a different shadow line and visual effect
| Joint Profile | Appearance | Common Era |
|---|---|---|
| Flush | Flat with the brick face, minimal shadow | Georgian, early Victorian |
| Bucket handle | Concave profile, gentle shadow line | Victorian, Edwardian (most common) |
| Weathered | Angled slope from top to bottom of joint | Victorian, good for exposed walls |
| Recessed | Set back from brick face, strong shadow | Modern, contemporary extensions |
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| Option | Cost per Brick/m² | Wall Cost (per m²) | Notes |
|---|---|---|---|
| New London stocks | £0.80-1.50/brick | £80-130/m² | Consistent supply, lacks patina |
| Reclaimed stocks | £1.00-3.00/brick | £100-220/m² | Authentic look, variable supply |
| Brick slips | £40-80/m² | £60-100/m² | Thin facing only, quick install |
| Re-pointing existing | N/A | £40-80/m² | Renew mortar joints on existing walls |
Wall costs include bricks, mortar, labour, and scaffolding. Add 10-15% for conservation area projects where sample panels and slower working are required.
Conservation Area Requirements
In conservation areas, planners are particularly rigorous about brick matching. Conditions attached to planning permissions commonly require:
- Sample panels: Build a 1m x 1m panel of brickwork on site using the proposed bricks and mortar for the planning officer to inspect and approve before the main build begins
- Material specifications: Submit exact brick name, manufacturer, and mortar mix specification as part of discharging planning conditions
- Bond pattern matching: Match the brick bond pattern of the existing building (Flemish bond, stretcher bond, English bond)
- Reclaimed bricks preferred: Many conservation officers prefer reclaimed bricks for the authentic weathered appearance. New stocks may be rejected if they look too “clean”
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Sourcing London Stock Bricks
Finding the right bricks requires visiting specialist suppliers. Standard builder's merchants rarely stock the range of London stocks needed for a good match.
Specialist Reclamation Yards
Reclamation yards in the Home Counties and Kent are the best source for authentic reclaimed London stocks. Visit in person to hand-select bricks from different batches. Expect to reject 10-20% of reclaimed bricks for quality issues (frost damage, excessive mortar, wrong size).
Brick Merchants with Heritage Ranges
Several major brick manufacturers now produce heritage-range London stocks designed to replicate the colour and texture of original bricks. These offer the consistency of new manufacture with a closer approximation to aged brickwork than standard new stocks.
Brick Matching Services
Some suppliers offer brick matching services where you send them a sample brick and they source the closest match from their stock. This saves time and takes advantage of their expert knowledge of available products.
Common Brick Matching Mistakes
These mistakes are seen frequently on London extension projects and are all avoidable with proper care during the specification stage.
- Wrong mortar type: Using hard cement mortar with soft stock bricks causes spalling and moisture damage. Always use lime mortar or a weak lime-cement mix
- Not enough variation: Selecting bricks that are too uniform. Real London stock walls have natural variation in colour and texture. Mixing bricks from different packs creates a more authentic appearance
- Ignoring weathering direction: The exposed face of a reclaimed brick has a specific weathering pattern. Laying bricks with the wrong face exposed creates an unnatural appearance
- Not building sample panels: Skipping the sample panel stage means you cannot assess the overall effect of brick and mortar together before committing to the full build. This is the most costly mistake to rectify
- Matching to a cleaned brick: Comparing new bricks to a freshly cleaned section of existing brickwork gives a misleading match. Always compare to the naturally weathered surface
Frequently Asked Questions
Frequently Asked Questions
How much do London stock bricks cost?
New London stock bricks cost £0.80-1.50 per brick, while reclaimed stocks cost £1.00-3.00 per brick depending on quality and availability. For a typical extension wall, expect to pay £80-130/m² for new stocks or £100-220/m² for reclaimed, including mortar and labour.
Should I use new or reclaimed London stock bricks?
Reclaimed stocks provide the most authentic match for conservation areas and older properties because they have natural weathering. New stocks are more consistent and readily available. For conservation areas, planners often prefer reclaimed. For non-conservation areas, quality new stocks with a heritage finish can be a good compromise.
What mortar should I use with London stock bricks?
Always use lime mortar or a weak lime-cement mix (1:1:6 or 1:2:9 cement:lime:sand). Never use a standard 4:1 cement mortar, which is too hard for soft London stock bricks and will cause moisture damage and face spalling within 5-10 years.
Do I need a sample panel for brick matching?
In conservation areas, a sample panel is often a planning condition. Even without a planning requirement, building a 1m x 1m sample panel is strongly recommended. It costs £200-400 and lets you assess the combined effect of brick, mortar colour, and joint profile before committing to the full build.
How do I find matching bricks for my Victorian house?
Remove a brick from a concealed area and take it to a specialist brick merchant or reclamation yard. Compare in daylight against the weathered (not cleaned) face of your existing brickwork. Get at least three different options and view them next to your wall before ordering.
Can brick slips match London stock brickwork?
Brick slips cut from genuine London stock bricks can provide a good match for specific applications like cladding over external insulation. However, they lack the depth and shadow lines of full bricks and may not satisfy conservation area requirements. They cost £40-80/m² installed.
Summary
Brick matching is a detail that separates good extensions from great ones. The investment in finding the right brick, specifying the correct mortar, and building a sample panel pays dividends in both planning approval and the long-term appearance of your home.
For most London extension projects, the key decisions are whether to use new or reclaimed stocks, and getting the mortar specification right. Take the time to visit specialist suppliers, take physical samples rather than relying on photographs, and always insist on a sample panel before the main build begins.
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