It is easy to compare the price of one block with the price of another. It is much more useful to compare the finished cost of a square metre of wall. Prices change from place to place and month to month, so this article gives you a method rather than numbers. Fill in your own local quotes.

Step 1: How many blocks per square metre?

Divide 1 square metre by the area of the block face you see in the wall. As an example, if the exposed face is about 254 mm by 102 mm (10 in by 4 in), the face area is roughly 0.0259 m², so you need around 39 blocks per square metre when joints are very thin. Always confirm with the actual block size and the wall design, and add an allowance for breakage and cutting.

Step 2: Cost of the block itself

For blocks you make yourself, add up for one batch:

• Soil (digging, transport, sieving)
• Cement
• Water
• Labour for mixing, pressing and curing
• Machine cost spread over its expected life (purchase price divided by the number of blocks you expect to make)
• Maintenance, shelter and fuel or power if any

Then divide the total by the number of good blocks produced. For bought blocks or stones, use the delivered price, not the price at the quarry gate.

Step 3: Everything else in the wall

• Mortar or grout (interlocking systems use less, but not zero)
• Reinforcement steel and ring beams
• Laying labour, which can differ between systems
• Plaster and paint, if used (see finishing options)
• Scaffolding, waste and wastage

Step 4: Put it together

Cost per m² = (blocks per m² × cost per block) + mortar + steel + laying labour + finishes + wastage allowance.

Calculate this for each walling option on the same wall design and the same assumptions.

Step 5: Look beyond the number

• Time: how long does each system take to build?
• Transport: how far must materials travel?
• Durability and maintenance over the building’s life
• Thermal comfort and cooling needs

Keep records

If you produce blocks yourself, track real costs for a month and update the worksheet. Your own numbers will be more reliable than any published figure.

For a comparison of materials, see concrete block construction in Kenya and soil blocks versus burnt bricks.

• budgeting
• costing
• walling