Blockwork cost per m², built up properly

Six times fewer units, but only half again the speed

A square metre of 100mm blockwork is ten blocks. The same square metre in facing brick is sixty. You would expect blockwork to be six times quicker, and it is not - the benchmark is 25 m² a day for the gang against 16.7 for brick, about half again.

The reason is weight and reach. A brick is a one-handed unit; a dense concrete block is a two-handed lift that has to be placed accurately, and the mortar bed is bigger. Fewer units does not mean proportionally less work when each unit is twenty times the mass.

Which block you are laying changes the day materially

• Dense concrete. Heavy, strong, and the slowest to lay. A 100mm dense block is around 20kg, and manual handling limits are a genuine constraint on a full day of them, not a formality - gangs slow down in the afternoon for a reason.
• Aircrete. Much lighter, cuts with a saw, and considerably quicker to lay. If your job is aircrete, push the output up.
• Thin joint systems. A different method with a different mortar and different output again - quicker in production, but with setting-out demands that punish an inaccurate first course.
• Solid or hollow. Fill and reinforcement change both the handling and the sequence.

One card, one slider: put the output where your block puts it.

The things that slow a blockwork gang

Blockwork looks like the simplest masonry there is, and on a long straight internal wall it very nearly is. What costs time is everything that interrupts the run:

• Openings. Doors and windows mean lintels, closing cavities, and cutting, and the square metres go down while the hours do not.
• Cavity work. Wall ties at centres, insulation boards, cavity trays and keeping the cavity clean is a second discipline running alongside the laying.
• Restraint and reinforcement. Wind posts, bed joint reinforcement and restraint straps to the frame are all slow, fiddly and non-negotiable.
• Cutting. A wall that does not work out to whole blocks vertically is a cut course, and cut blocks are heavy, dusty and slow.

Pricing blockwork on a real job

The gang is two tradespeople and a labourer for the same reason as brickwork: one labourer keeps two people in blocks and mortar and no more, and blocks are heavier to move than bricks. Leaving the labourer out of the price is the same third-of-the-labour error it is on brick, and it is easier to make here because blockwork “feels” like simpler work.

Blocks, mortar, ties, insulation and lintels are materials. Scaffold, once you are above a lift, is a lump sum in the job section - priced by lift and elevation, never by wall area.