Bricks or concrete blocks: what to build walls with

Why blocks are on the rise

Brick kilns burn coal and consume agricultural topsoil. The government has set targets to phase fired clay bricks out of public construction in favour of blocks, and block manufacturing capacity has grown in response. Private developers are following where the numbers work.

How the two compare

• Weight: hollow blocks make a lighter wall, which reduces the load on beams, columns and foundations.
• Speed: a block covers the area of several bricks, so walls go up faster with fewer joints.
• Mortar and plaster: fewer joints and more regular faces mean less mortar and thinner plaster.
• Consistency: machine-made blocks are uniform in size. Brick quality varies from kiln to kiln and batch to batch.
• Familiarity: every mason knows brickwork. Block work needs some training and the right detailing.
• Fixings: heavy fixtures into hollow blocks need suitable anchors or filled cores.

If you are buying bricks

• First-class bricks are uniform in colour and shape, with sharp edges.
• Two bricks struck together should give a clear ringing sound.
• A brick dropped flat from about a metre onto firm ground should not break.
• A brick soaked for a day should not take up more than about a fifth of its weight in water.
• Avoid over-burnt, twisted bricks and pale, under-burnt ones.

If you are buying blocks

• Ask for the compressive strength and the test report behind it.
• Check that blocks have been cured properly before delivery. Fresh blocks shrink and crack the wall.
• Confirm the sizes available, including half blocks and lintel blocks, so cutting is kept down.
• Agree how they will be unloaded. Blocks chip if tipped.

Which one to choose

For partition and infill walls in framed buildings, blocks usually win on weight and speed. For small load-bearing buildings and where skilled block masons are scarce, good bricks remain a sound choice. Decide early: the choice changes the dead load the structural engineer designs for.