How do you estimate mortar required for 1m2 of block work?

To estimate the mortar required for 1m² of block work, first determine the size of the blocks and the joint thickness. Typically, a joint thickness of about 10mm is used. Calculate the volume of mortar needed by multiplying the area of the joints (perimeter of the blocks multiplied by the height, divided by the joint thickness) by the joint thickness. A common estimate is that you'll need around 0.1 to 0.15 cubic meters of mortar for every cubic meter of block work, which translates to approximately 20-30 kg of mortar per m² of block work, depending on the block size and joint thickness.