Facing Bricks: How to Choose, Match, and Order for Your Extension

Get the brick wrong and the extension looks like an extension forever. The colour matters, but so does the texture, the size, and the mortar colour. Get any of them wrong and your new structure announces itself to every visitor regardless of how well it's built. Of all the material decisions on a masonry extension, facing brick selection carries the most lasting visual consequences, and it's the decision that catches homeowners out most often.

What facing bricks are and what they're for

Facing bricks are clay or concrete masonry units manufactured specifically for external, visible applications. The "facing" designation means they are selected and graded for their appearance as much as their structural performance. In UK cavity wall construction, they form the outer leaf: the part of the wall everyone sees.

The standard metric facing brick is 215 mm long, 102.5 mm wide, and 65 mm tall. Add 10 mm mortar joints and the coordinating module becomes 225 x 112.5 x 75 mm. That module is the basis for every quantity calculation. The width (102.5 mm) is what you'll hear called "half-brick" width, because a full-brick wall is two leaves bonded together.

Properties built before the early 1970s will likely have imperial bricks. These ran approximately 228 x 110 x 68 mm (though actual sizes varied by manufacturer and region). The 13 mm difference in length and 3 mm difference in height seems trivial until you try to bond new metric bricks against imperial courses. The mortar bed has to compensate, and the course lines never align perfectly. If your house is pre-1970s, you need to source imperial-sized bricks, not assume metric will do.

All UK-sold facing bricks must comply with BS EN 771-1, the European harmonised standard for clay masonry units. It sets the technical requirements: dimensional tolerances, compressive strength, frost resistance, and soluble salt content. Any brick from a reputable merchant will carry a Declaration of Performance showing the tested values for those properties. The two numbers that matter most for external use are the frost resistance category and compressive strength.

Types, sizes, and specifications

The key decision is not which type you prefer, it's which type matches your existing house. The extension wall will be adjacent to original brickwork for the rest of time. Getting a close visual match requires getting the type right first, before worrying about specific colour.

Frost resistance: F0, F1, F2

Under BS EN 771-1, all clay facing bricks are assigned a frost resistance category:

• F2 - frost resistant in all normal building situations. This is what you want for external walls.
• F1 - moderately frost resistant. Acceptable for general wall areas between DPC and eaves in sheltered locations in England and Wales, but not for exposed elements.
• F0 - not frost resistant. For internal or protected use only. Never specify F0 for external facing brickwork.

Where F2 is non-negotiable regardless of location:

• All brickwork below the damp-proof course (DPC)
• Copings, sills, and capping
• Chimneys and parapet walls
• Any brickwork in Scotland (all external clay bricks must be F2,S1 or F2,S2 under Scottish requirements)

The frost resistance category tells you about the clay's durability under freeze-thaw cycling. Compressive strength does not predict frost resistance. A high-strength brick can be F0. A moderate-strength brick can be F2. They are independent properties. Do not assume strength implies frost resistance.

Soluble salt content is a second BS EN 771-1 category (S0, S1, or S2), where S2 means the lowest soluble salt content. In aggressive exposure conditions, specify F2,S2 or F2,S1. Your brick supplier's product data sheet will show both classifications.

Compressive strength

For domestic extension outer leaf work, minimum 9 N/mm2 compressive strength for one- or two-storey buildings is the NHBC and industry baseline. Most standard facing bricks exceed this. Three-storey work requires minimum 13 N/mm2. Your structural engineer will specify the minimum if it differs from the standard.

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How to work with facing bricks

What they weigh and how they handle

A standard metric facing brick weighs approximately 2.5-3.5 kg depending on clay density and moisture content. A pack of 500 bricks weighs 1.25-1.75 tonnes. Factor vehicle access and pallet positioning carefully. A flatbed crane-arm lorry needs firm ground and reasonable access; the driver won't carry bricks 50 metres across a soft garden.

Handmade stock bricks vary more in weight because the clay is less consistently compacted. Reclaimed bricks arrive with varying degrees of residual mortar, which adds bulk and weight to the delivery.

Store bricks off the ground on the delivery pallet (or on a dry, raised platform) and cover with a tarpaulin to prevent excessive moisture absorption before laying. Wet bricks absorb mortar water unevenly and can cause joint cracking as they dry.

Cutting facing bricks

An angle grinder with a diamond masonry disc cuts facing bricks cleanly. Score the cut line first, then cut through. Always cut outside or in ventilated conditions. Brick cutting generates silica dust, which is a serious cumulative lung hazard. Wear a P3 dust mask (not a basic paper mask), safety glasses, and hearing protection without exception.

A bolster chisel and club hammer will split bricks along a scored line for rough cuts. The cut won't be as clean as a disc cut. Acceptable for hidden closing cuts; not for visible faces.

For high volumes of the same cut, a bench-mounted diamond block saw gives the most consistent results. Worth hiring from a tool hire shop for projects where you're cutting 50+ bricks to the same dimension.

Laying facing bricks

Facing bricks are laid in mortar. For most domestic extension outer leaf work, a 1:1:6 cement:lime:sand mix (or a 1:6 cement:sand mix with plasticiser) gives workable consistency and adequate strength. The mortar designation and mix ratio may be specified on your structural engineer's drawings; use what's specified.

Keep bed joints (horizontal) and perpends (vertical joints) consistent at 10 mm. Inconsistent joints are visible from ten metres. They're a building control defect and an NHBC flag.

The bond pattern must match the existing house. Stretcher bond (half-overlap) is most common in modern UK construction. English bond (alternating courses of stretchers and headers) and Flemish bond (alternating stretchers and headers in each course) appear in Victorian and Edwardian properties. Matching the bond pattern is as important as matching the brick. A sample panel built in the wrong bond will look wrong even if the brick colour is perfect.

Matching existing brickwork

Brick matching goes wrong constantly. Community forums are full of posts showing extension brickwork that looks nothing like the house it's attached to. The failure mode is almost always the same: the homeowner trusted the builder to sort it, the builder sourced whatever was available, and nobody built a sample panel before laying commenced.

Your builder's job is to build. Specifying the correct brick is your responsibility as the project manager.

Step 1: Identify what you have

Take three or four bricks from a corner or other inconspicuous location and measure the length, width, and height precisely. Photograph them in natural daylight (overcast light, not direct sun). Note whether the edges are sharp or soft, the face texture (smooth, dragged, creased, sand-faced), and the colour including any variation within the same wall. Also photograph the mortar joint colour and profile.

Determine whether the bricks are imperial or metric. Measure the height of ten courses including mortar joints. Metric: ten courses should measure 750 mm (65 mm brick + 10 mm joint = 75 mm per course). Imperial: ten courses will measure closer to 790 mm (68 mm brick + 10 mm mortar = 78 mm per course). If the measurement is closer to 790 mm, you have imperial bricks and need imperial-sized replacements.

Step 2: Identify when the house was built

The build date gives you context. Properties built before ~1970 are likely imperial brickwork and may have handmade, pressed, or early wirecut bricks that are no longer in production. Properties from the 1970s-90s typically have metric wirecut bricks. Post-2000 properties have modern wirecut bricks with a wide range of manufacturer matches available.

Regional colour patterns matter. Yellow and buff stocks dominate London and the South East. Deep red and orange reds are common in the North and Midlands. Blue-grey wirecuts appear in parts of the West Midlands. If you're in London trying to match buff stock bricks, most standard wirecut options won't be close.

Step 3: Use a matching service

Don't guess. The two main specialist routes are:

Brickhunter (brickhunter.com) offers a matching service for £29.99 inc VAT, refunded against the purchase price if you buy through them. They hold approximately 4,000 bricks in their library and have relationships with Forterra, Ibstock, Michelmersh, and Wienerberger. Send your sample brick and photos; they search for the closest available match. For older and unusual bricks, this is often the most reliable route.

Manufacturer matching services at Ibstock, Wienerberger, and Forterra are free. Call them with measurements and photos. They'll suggest matches from their current ranges and heritage collections. Ibstock has over 270 products in their range. Wienerberger offers the widest selection of special formats and historic replicas in the UK market.

For post-2000 houses, your builder's merchant can often match by sight if you bring a sample brick. For anything pre-1980, use a specialist matching service. The time investment is minimal compared to having to live with a mismatched wall.

Step 4: Build a sample panel

Order 50-100 sample bricks of your proposed match before ordering the full quantity. Lay a 1 m2 sample panel against the existing wall. View it at different times of day (morning light, midday, dusk). Mortar colour matters more than most homeowners expect.

Mortar accounts for 15-20% of the visual wall surface. The same brick looks completely different with grey mortar versus buff mortar versus white mortar. Use the same mortar colour as the existing wall. If you're unsure what the existing mortar colour is, a specialist can send a small sample for chemical analysis at approximately £200. Cheaper than re-pointing a whole elevation with the wrong colour.

If the sample panel looks right at different lighting conditions, order the full quantity. If it doesn't look right, keep searching. The decision is much cheaper to reverse at this stage.

Step 5: Order in a single batch from the same kiln run

Brick colour varies between production runs at the same factory. Two pallets ordered six months apart may be slightly different. Order your full quantity in a single batch. If you need 2,200 bricks, order 2,500 in one go. The excess will be used at boundaries, in outbuildings, or as repairs.

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How many bricks do you need

The calculation starts from the 60 bricks per m2 figure for stretcher bond. That comes from the coordinating module: 225 mm wide x 75 mm tall = 1 m2 / (0.225 x 0.075) = 59.26 bricks, rounded up to 60.

English bond and Flemish bond use more bricks per m2 because headers (bricks laid end-on) appear in the bond. English bond uses approximately 90 bricks per m2. Flemish bond uses approximately 80. If your existing house is in English or Flemish bond, factor the higher count into your order.

A worked example for a 4 x 6 m single-storey rear extension:

• Front and rear faces: 2 walls, each 4 m wide x 2.4 m high = 19.2 m2 total
• Side faces: 2 walls, each 6 m long x 2.4 m high = 28.8 m2 total
• Total gross wall face area: 48 m2
• Subtract windows and doors: typically 6-8 m2 for a standard rear extension
• Net brick area: approximately 40-42 m2
• Bricks at 60/m2: 2,400-2,520 bricks
• Add 5-10% wastage: 2,520-2,772 bricks
• Round to packs (packs of 400-500 depending on supplier): order 3,000 bricks in one batch

For reclaimed bricks, allow 10-15% wastage rather than 5-10%, because reject rate is higher on salvaged stock and consistency is lower. It's better to have 200 spare reclaimed bricks than to need to source a second batch that may not match the first.

Cost and where to buy

New facing bricks range from £0.40 – £2.53 each (ex VAT). That translates to £400 – £2,500 per 1,000 depending on type.

Prices above are ex VAT unless stated. Add 20% for consumer purchases. Trade accounts at builders' merchants receive meaningful discounts below list price, particularly on pallet quantities.

For 2,500-3,000 bricks, a full pallet order through a builders' merchant (Travis Perkins, Jewson, Buildbase) or specialist brick supplier (Brickhunter, UK Bricks, Build4less) is usually the most cost-effective route. Delivery adds £50-80 per pallet for most suppliers; confirm at point of ordering. Some merchants offer free delivery above a threshold spend.

Reclaimed bricks from architectural salvage yards (Watling Reclamation, LRBM, SalvoWEB, Authentic Reclamation) are priced at £800–2,000 per 1,000. London salvage yards sit at the upper end of that range. Regional yards and online salvage marketplaces can be cheaper, but availability of consistent matching stock is variable.

The four main UK manufacturers

You won't always choose which brand arrives on your pallet. Merchants stock what they have. But knowing who makes what helps you cross-check whether what you've been sent is what was specified.

Ibstock is the largest brick manufacturer in the UK, with 19 plants producing approximately 780 million bricks per year. Over 270 products covering wirecut, handmade, and pressed formats. Their brick matching service is free and handles the majority of post-1970s matching requests easily.

Forterra (formerly Hanson, part of their LBC range) is the only UK manufacturer of original Fletton/London brick. 29% of UK brick manufacturing capacity by production volume. Their LBC range includes the Tudor, Heather, and Dapple Light facings widely used on 1970s-90s housing. If your house is from that era, Forterra LBC is often the closest match.

Wienerberger (UK subsidiary of the Austrian parent) offers the widest range of special-format bricks in the UK: long-format, waterstruck, glazed, tumbled, and bespoke specials. Strong for Victorian and Edwardian stock brick matching. Bespoke specials service for unusual historical formats.

Michelmersh is a smaller premium UK manufacturer specialising in handmade and stock bricks, strong for heritage character work. Their Multi Stock brick is a common choice for period property extensions.

Alternatives

If the visible wall area is small or the budget is tight, heritage-style wirecut bricks from the main manufacturers can replicate period aesthetics at lower cost and shorter lead times than true handmade bricks. Ibstock's Sovereign, Wienerberger's Waterstruck range, and Forterra's Natural Rustic are all designed to approximate handmade character from a machine process. They're not identical under close inspection, but they're far closer than a standard smooth wirecut and cost considerably less than genuine handmade stock.

For sections of wall that are entirely hidden, such as the side wall of an extension built against a boundary fence or in an alley, there's no reason to use facing bricks. Concrete blocks or common (non-facing) bricks are fine for non-visible elevations, and the cost difference across several m2 is worth capturing.

Engineering bricks are specified below the DPC in some structural engineer's drawings, particularly in high-water-table locations or where ground conditions are aggressive. Engineering bricks offer lower water absorption than most facing bricks, but they do not provide a visual match to facing brickwork above DPC and are not used for visible external walls. See the engineering bricks guide.

Where you'll need this

Facing bricks appear on the outer leaf of any masonry extension or renovation with visible external walls:

• Walls and blockwork - outer leaf of the cavity wall, approximately 60 bricks per m2 in stretcher bond; matching the existing house brickwork is the primary challenge

These materials appear across the structure phase of any extension or renovation project involving masonry cavity wall construction.

Common mistakes

Not building a sample panel. This is the highest-frequency failure in extension brickwork. It appears in community forums more than any other brickwork complaint. Building a 1 m2 panel takes half a day. Not building one risks an entire elevation that looks wrong. Build the panel.

Ignoring mortar colour. The brick gets the attention; the mortar gets overlooked. The mortar joint is 10 mm wide in a 75 mm course. That's 13% of the visible surface per horizontal joint, and vertical perpends add more. Get the brick right and the mortar wrong and the wall still looks mismatched. Test mortar colour in the sample panel.

Ordering metric bricks for an imperial house. Properties built before the early 1970s almost certainly have imperial bricks. Metric bricks laid against imperial courses will have course lines that diverge across the wall height. This cannot be fully corrected with mortar bed adjustment. Match the size first.

Using F0 or F1 bricks in exposed locations. This appears in NHBC defect records as a recurring post-completion failure. Frost damage shows as spalling (face of the brick breaking away) and cracking, usually appearing in the first 2-3 winters. Use F2 below DPC, for copings, and for any exposed element without exception. In Scotland, use F2 for the entire external leaf.

Ordering in multiple batches. Brick colour varies between kiln firings at the same factory. Ordering 2,000 bricks in January and 500 more in April to make up a shortfall will likely result in visible colour variation across the wall. Order the full estimated quantity plus 10% contingency in a single consignment.