What is the standard size of a UK brick?

The standard UK brick size is 215mm long x 102.5mm wide x 65mm tall. With a 10mm mortar joint, this gives a repeating unit of 225mm x 75mm. This is commonly referred to as a 'one-brick' unit. Three courses of brick plus three mortar joints equal 225mm in height.

What is the difference between facing brick and engineering brick?

Facing bricks are manufactured to be aesthetically pleasing and are used on visible external walls - they come in a huge variety of colours, textures, and finishes. Engineering bricks (Class A and Class B) are dense, low-absorption bricks with high compressive strength, used where durability and moisture resistance are critical - damp proof courses, manholes, retaining walls, and below-ground work.

What is a frog in a brick?

A frog is the indentation or recess in the top face of a brick. It reduces the weight of the brick, helps key the mortar, and improves the bond between courses. Frogs should always be laid facing upward so they fill with mortar - laying frog-down creates a hollow joint that reduces strength and allows water to pond.

Brick - Construction Glossary

Q: How many bricks do I need per square metre?

For a standard half-brick (102.5mm) thick wall using standard UK bricks (215x65mm) with 10mm mortar joints, approximately 60 bricks are needed per square metre of wall face. For a full one-brick (215mm) thick wall, approximately 120 bricks per square metre are required.

Definition

A brick is a rectangular masonry unit made from fired clay, calcium silicate (sand-lime), or concrete, used to construct walls, columns, arches, and other structures by laying in bonded courses with mortar. The standard UK brick measures 215mm x 102.5mm x 65mm - designed so that with a 10mm mortar joint, three courses equal exactly 225mm in height.

In practice

Bricks are broadly classified by their use and properties. Facing bricks are selected for appearance and are used on visible external walls - available in hundreds of colours, textures, and finishes from machine-made through to handmade. Engineering bricks (Class A and B to BS EN 771-1) are dense, low-absorption units with high compressive strength, used for DPCs, manholes, below-ground work, and retaining walls. Common bricks are lower-specification units used in hidden structural work.

Approximately 60 bricks are needed per square metre of half-brick wall. Bricks are laid in a bond pattern - the arrangement of bricks across and through the wall - to distribute load and prevent continuous vertical joints. Common bonds include Stretcher bond (the standard for cavity wall outer leaves), English bond, and Flemish bond.

Building Regulations

StandardBS EN 771-1 - Clay masonry units

Standard size215 x 102.5 x 65 mm

Engineering brick Class AMin 125 N/mm² compressive strength, max 4.5% water absorption

Engineering brick Class BMin 75 N/mm² compressive strength, max 7% water absorption

Brick specification forms part of the structural masonry design under Approved Document A. BS EN 771-1 classifies clay bricks and sets out testing requirements. For external walls in new dwellings, the completed wall assembly must also meet the U-value requirements of Approved Document L.

Full Building Regulations guidance

Related Calculators

Brick Calculator Brick Slip Calculator

Brick

Just so you know...