Mortar
Repointing volume
- where
- joint fraction of the face
- unit length (mm)
- unit height (mm)
- perpend (mm)
- bed (mm)
- net mortar (litres; m² × mm = litres)
- face area (m²)
- pointing depth (mm)
- mortar with allowance (litres)
- waste (%)
Explain this equation
This estimates the mortar needed to point or repoint a wall face, from how much of the face is joints and how deep they are raked out.
L and H are the unit length and height, and j_v and j_h are the perpend and bed widths, all in mm. f is the share of the face that is joints. A is the face area (m²), d the depth (mm) and V the mortar (litres). V_o adds the waste w.
LH is the face of one unit and (L + j_v)(H + j_h) is that unit with its joints, so their ratio is the share of the face that is brick. One minus that is the share that is joint. Multiplying area, joint share and depth gives the volume; 1 m² × 1 mm is exactly one litre, so no conversion is needed.
Standard bricks with 10 mm joints give f ≈ 0.17. Ten square metres pointed 20 mm deep needs about 34 litres, about 38 with 10% waste.
Watch out: this assumes uniform rectangular joints, fully filled. Deep voids or irregular walls need more.
Estimate the rectangular joint-face fraction and pointing depth.
Enter your values to see the result.
Good to know
Uniform fully filled rectangular joints; no allowance for deep voids or irregular masonry. Do not use this to select repair depth or mortar compatibility.
Sources
- Geometry / arithmetic
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.