Blockwork vs brickwork: what is the difference?

The quick answer

Blockwork is walling built from concrete blocks, which are much larger than bricks and quicker to lay. Brickwork is walling built from clay or concrete bricks, chosen for looks and weather resistance. On most modern houses and extensions they are used together: brick on the outside face that people see, block on the inside where the wall is plastered, with an insulated cavity between them.

Size and speed

A standard UK brick is small enough to lay with one hand. A standard concrete block covers the face area of several bricks, so a bricklayer builds wall area faster with block. That speed is why block is used wherever the wall will be hidden behind plaster, render or cladding.

Blocks come in different densities. Dense blocks are heavy and strong, used below ground and where loads are high. Lightweight aerated blocks are easier to handle and insulate better, so they are common for the inner leaf of cavity walls.

Appearance and weather

Facing bricks are made to be seen. They come in many colours and textures and weather well without any coating. Most blocks are not designed to be left exposed; they are usually plastered inside or rendered outside. Where a new extension must match the house, the outer leaf is almost always brick so it blends with the original walls.

The cavity wall

A typical extension wall has two leaves: facing brick outside, block inside, with a cavity containing insulation. Metal wall ties link the two leaves so they act together. The brick keeps the weather out and gives the finished look; the block carries floor and roof loads and gives a flat surface to plaster. Below ground, the footing is often built in dense block or engineering brick, because appearance does not matter there and resistance to moisture does.

Garden walls and outbuildings

Free-standing garden walls are usually built in brick all the way through, because both faces are on show and the coping sits on top. A block wall can be cheaper for a hidden boundary or a retaining wall that will be faced or rendered. Brick-built garden rooms and outbuildings often use the same brick-and-block cavity construction as an extension, which is why they feel like part of the house rather than a shed.

Which should you choose?

It is rarely a choice between one or the other. For anything visible, brick gives the finish; for anything hidden or plastered, block gives speed and insulation. The drawings and Building Regulations usually set the wall build-up for habitable rooms, and your builder should explain it in the quote. For garden walls, the decision comes down to whether both faces will be seen and whether a render finish would suit the garden.

Laying and bonding differences

Bricks are laid in bonds such as stretcher, English or Flemish bond, and the pattern is part of the finished look. Blocks are almost always laid in simple stretcher bond because they are hidden. Block joints are the same thickness as brick joints, so on a cavity wall the block courses are set out to line up with every few brick courses, which lets wall ties sit level across the cavity. Around windows and doors, lintels span the openings in both leaves, and cavity closers seal the gap so heat and damp cannot bypass the insulation.

About us

D & A Brickwork & Building is a family-run firm based in Bidwell, Dunstable. We have more than 26 years of building experience, our bricklaying is NVQ Level 2 qualified, we are members of the Federation of Master Builders and we are fully insured. Estimates are free and follow a visit to see the job.

Brick-and-block walling is the core of what we build, on extensions, garage conversion infills, garden rooms and boundary walls.

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