Mortar
Mortar volume: geometric estimate
- where
- number of units
- net face area (m²)
- unit length (mm)
- perpend joint (mm)
- unit height (mm)
- bed joint (mm)
- mortar in joints (m³)
- leaf thickness (mm)
- allowance (%)
- mortar with allowance (litres)
Explain this equation
This estimates the volume of mortar in the joints of a single leaf of rectangular units, then adds an allowance and gives the answer in litres.
A is the net face area. L and H are the unit length and height in mm, j_v is the perpend and j_h the bed. N is the number of units in the area. T is the leaf thickness in mm. V_j is the mortar in the joints in m³, and w is the allowance percentage.
First the units are counted, as in the brick calculator. Then A × T is the whole volume of the leaf and N × L × H × T is the solid volume of the units; the difference is the mortar. The 1000 turns mm to metres, and 1 000 000 000 turns mm³ into m³. The final × 1000 converts m³ into litres.
Ten square metres of half-brick wall with 10 mm joints holds about 0.176 m³ of mortar. With 10% allowance that is about 194 litres.
Watch out: frogs and perforations are ignored. Order from manufacturer yields.
Estimate joint space in one rectangular-unit leaf.
Enter your values to see the result.
Good to know
Full rectangular units with full beds/perpends. Excludes frogs, perforations, wastage beyond your allowance and cavity losses. Use manufacturer yield for actual ordering.
Sources
- Geometry / MPA yield distinction
Estimates are not design approval or British Standards compliance checks. Structural arch, retaining-wall, wind, foundation, lintel and masonry-capacity design are not performed. Use the project engineer’s specification.