Brick Types Guide: Engineering, Common, Facing and Handmade — Selecting for the Right Application

Quick Answer: UK bricks are classified under BS EN 771-1 by frost resistance (F0/F1/F2), water absorption (T/M/TM/S), and soluble salt content (S0/S1/S2). Engineering bricks (Class A and B) have the highest compressive strength and lowest water absorption; facing bricks are specified for appearance. Standard UK brick dimensions are 215×102.5×65mm, giving 75mm coursing with a 10mm bed joint.

Summary

Brick selection is one of the most consequential decisions on any masonry construction project. The wrong brick in the wrong application leads to: freeze-thaw spalling in exposed positions, efflorescence from inappropriate salt content, structural failure in high-load applications, and aesthetic failure when a facing brick weathers poorly. Yet many projects specify bricks based on colour and price alone, ignoring the technical classification system that determines actual performance.

BS EN 771-1 (the European standard for fired clay bricks, which replaced BS 3921 in the UK) provides a comprehensive classification system. Understanding this system allows accurate specification of bricks for any application — from a garden wall to a multi-storey structural frame. This article covers the key classification parameters, the main brick types available in the UK market, and their appropriate applications.

Key Facts

Quick Reference Table

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Brick Type Compressive Strength Water Absorption Frost Class Typical Use
Engineering Class A ≥125 N/mm² ≤4.5% F2 Manholes, below DPC, retaining walls, paving
Engineering Class B ≥75 N/mm² ≤7% F2 Below DPC, hard-wearing surfaces
Facing brick (premium) 20–50 N/mm² 6–12% F1 or F2 External facing; decorative
Facing brick (standard) 15–30 N/mm² 10–18% F1 External walls; sheltered
Common brick 15–25 N/mm² Variable F0–F1 Internal work, backfill, non-visible
Handmade brick 20–50 N/mm² 8–15% F1–F2 Premium facing; heritage
Reclaimed brick Variable Variable Variable Heritage match; verify classification
Calcium silicate 20–50 N/mm² N/A F2 equivalent Facing and internal; uniform colour

Detailed Guidance

Engineering Bricks

Engineering bricks are the workhorses of the brick world — dense, strong, and virtually impermeable. They are the correct specification for any application where structural loads, moisture resistance, or chemical attack are primary concerns:

Class A Staffordshire Blue Engineering Brick:

Class B Engineering Brick:

Applications where engineering bricks are required:

Common Bricks

Common bricks (sometimes called commons) are workmanlike bricks without decorative face quality requirements. They have no BS EN 771-1 appearance classification:

Facing Bricks

Facing bricks are specified primarily for their appearance. They must have:

Wire-cut facing bricks:

Extruded (pressed) facing bricks:

Handmade facing bricks:

Selecting facing bricks for exposure:

Exposure Category Recommended Frost Class Salt Class Notes
Very severe (coast, high ground) F2 S2 Check with manufacturer for coastal suitability
Severe (most UK external) F2 S2 Standard for all exposed external walls
Moderate (urban, sheltered) F1 minimum S1 minimum Above DPC; rain shelter
Mild (sheltered, under eaves) F1 S1 Rarely fully exposed

Reclaimed Bricks

Reclaimed bricks are salvaged from demolition and re-used. They are popular for heritage matching and architectural character:

BS EN 771-1:2011 requirements for reclaimed bricks:

Practical considerations:

Heritage matching: For listed building repairs and conservation area work, matching the existing brick by colour, texture, and dimension is essential. A specialist reclaimed brick merchant can often match within two to three shades. For exact matches, take a sample brick to the merchant rather than describing colour.

Calcium Silicate Bricks

Calcium silicate bricks (sand-lime or flint-lime bricks, BS EN 771-2) are manufactured by autoclaving a mix of sand (or crushed flint) and lime under high pressure:

Concrete Bricks

Concrete bricks (BS EN 771-3) are manufactured from dense concrete aggregate:

Standard UK Brick Dimensions

Dimension Nominal Size Coordinating Size (including joint)
Length 215mm 225mm (with 10mm joint)
Width (header face) 102.5mm 112.5mm
Height 65mm 75mm

Coursing: 4 courses = 300mm; 8 courses = 600mm. Use this for setting out openings and calculating brick quantities (see brick quantities).

Metric vs imperial: Many UK properties were built with imperial bricks (3" × 9" × 4½"). The slight size difference (65mm metric vs 73mm imperial with joint) means coursing does not match between old and new work. Extensions and repairs to pre-1970s buildings require careful coursing adjustment or special purpose bricks to maintain course alignment.

Frequently Asked Questions

How do I match bricks for a house extension?

Matching existing bricks is one of the most challenging aspects of extension work. Start by identifying: the brick colour and texture; the course height; and whether the brick was laid with a weathered, bucket-handle, or flush joint. Take a sample brick to a brick merchant — do not rely on written descriptions or photographs. Be prepared to source reclaimed bricks for an older property where current production does not closely match. Budget for 10–15% extra over the calculated quantity for selection/rejection of poor matches.

What is the minimum compressive strength needed for a garden wall?

For a single-skin garden wall in a non-load-bearing position, most facing bricks with 15–20 N/mm² compressive strength are adequate. The more important specification for a garden wall is frost resistance (F2 required for fully exposed conditions) and water absorption (T or M for coping bricks). The mortar specification is equally important — use a 1:1:6 cement:lime:sand mortar for flexibility; do not use a hard cement mortar on softer facing bricks.

Can I use common bricks in an exposed position if I render them?

Yes, if the render fully covers the brick and prevents water ingress. Common bricks are fine as a substrate for render (the higher porosity of commons gives good render key). However, the render system must be continuous and well maintained — any cracking allows water penetration. Use a lime-based render on historically inappropriate (pre-1930s) brickwork; cement render on modern construction. The render specification must also be frost-resistant at the finish coat level.

What does 'S0' mean on a brick data sheet?

S0 means no specific classification for soluble salt content has been stated (under the old BS EN 771-1 marking scheme). The current standard uses S1 and S2; S1 indicates higher soluble salt content acceptable only for protected positions; S2 indicates low soluble salt content suitable for external work. Bricks marked S0 should be treated cautiously for external use — request the manufacturer's test data on soluble salt content before specifying in fully exposed locations.

Regulations & Standards