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5.1 Laying bricks and blocks

Mortar for walls, piers, garden walls and block foundations.

Elevation of a brick wall in stretcher bond: bricks with 10 mm mortar bed joints and head joints, on a concrete footing. 3 Bricks or blocks laid in stretcher bond 2 Mortar joints 10 mm · 0–2 or 0–4 mm sand 1 Footing cured concrete, see 4.2
Wall face. Every brick sits on a 10 mm bed joint and is joined to the next by a 10 mm head joint.

At a glance

Difficulty
3 of 4
Joints
10 mm bed and head joints
Tools
Mixer or mixing board, bucket, brick trowel, spirit level, line and pins, gauge rod, jointer
Parts
  1. 1  Footing
  2. 2  Mortar joints
  3. 3  Bricks or blocks

What you need per m² of wall, 1 : 1 : 6 mortar

MaterialSizeTypeBrick wallBlock wall
Bricks or blocks – Brick 215 × 102.5 × 65 mm, block 440 × 215 × 100 mm 6010
Sand 0–4 mm Washed, well graded 40 kg12 kg
or 0–2 mm Finer, for neat thin joints
Cement – CEM I or CEM II 6 kg1.7 kg
Hydrated lime – Building lime, for workability 1.7 kg0.5 kg

Why 0–2 or 0–4?

0–4 mm

The general mortar sand. Grains up to 4 mm still fit a 10 mm joint with paste around them.

0–2 mm

Finer sand. Gives a neat, smooth joint face. Sand with more fines needs the lower sand figure, for example 1 : 1 : 5 instead of 1 : 1 : 6.

Step by step

  1. 1

    Check the footing is level and clean.

    Bricks follow the base. Set out the first course dry to check the bond and avoid cut bricks at the ends.

    Spirit level on the footing
  2. 2

    Mix 1 cement, 1 lime, 6 sand by bucket.

    Mix the dry parts first, then add water until the mortar is soft and holds a ridge on the trowel. Make only as much as you can use before it stiffens.

    The mix, bucket by bucket
  3. 3

    Build the corners first.

    Raise each end a few courses, checking level and plumb on every course, and keep each course to the same height with a gauge rod.

    Corners raised and checked
  4. 4

    Fill in between along a string line.

    Stretch a line between the corners at the top of the course. Lay a full bed of mortar, butter the end of each brick and tap it down to the line.

    Laying to the line
  5. 5

    Tool the joints when thumb-hard.

    Press a jointer along the joints once the mortar is firm to the touch. It seals the joint face so rain runs off.

    Tooling a joint
  6. 6

    Protect new work from rain and frost.

    Cover the top of the wall overnight and until the mortar has hardened. Do not lay bricks when frost is expected.

    Wall top covered
Specifications
PartSieve sizeThicknessHow
1 Footing––Level and cured. See 4.2.
2 Mortar joints0–4 mm or 0–2 mm10 mmFull beds and full head joints. Tooled when thumb-hard.
3 Bricks or blocks––Stretcher bond, level and plumb each course.

Which mix

Cement : lime : sand by volume. 1 : 1 : 5–6 (class M4) for ordinary walls above ground. 1 : ½ : 4–4½ (M6) below ground and in the courses just above it, where the wall stays wet. Use the lower sand figure with sands that hold more fines.

Bricks and blocks per m²

With 10 mm joints each brick of 215 × 65 mm takes up 225 × 75 mm of wall, so 1 m² holds about 60 bricks. A 440 × 215 mm block takes up 450 × 225 mm, about 10 per m².

How much mortar

Work it out from the joints. In brick walls mortar is about 22 % of the wall volume. In a 100 mm block wall with 10 mm joints it is about 7 %. Dry materials take about a third more volume than the mixed mortar. Add about 10 % for losses. Thicker blocks need more.

Sand

Clean, washed sand made for mortar (EN 13139 in Europe, ASTM C144 in North America). Sand that is mostly one grain size, or full of clay, makes weak mortar that shrinks.

Sources

  1. NA to BS EN 1996-1-1 UK National Annex to Eurocode 6 (BSI 2007), Table NA.2: mortar classes M12, M6, M4, M2 with cement : lime : sand 1 : 0–¼ : 3, 1 : ½ : 4–4½, 1 : 1 : 5–6, 1 : 2 : 8–9 by volume (designations i–iv); the lower sand figure for sands with more fines, the higher for sands with fewer
  2. UK Building Regulations, Approved Document A (2004 edition incorporating 2010 and 2013 amendments), paragraph 2C22: wall mortar of designation (iii), strength class M4 to EN 998-2, or 1 : 1 : 5–6 cement, lime and fine aggregate by volume of dry materials
  3. Specification for Highway Works, Series 2400: brickwork, blockwork and stonework (National Highways): Table 24/1 mortar proportions; sand to EN 13139; allow for bulking of sand; Table 24/5 asks for designation (i) or (ii) below 150 mm above finished ground level (for masonry arch bridges)
  4. British Brick Society, Information compilation vol. I (hosted by the University of Cambridge Department of Architecture), "The Size of the Brick": the British Standard metric brick is 215 × 102.5 × 65 mm and is laid with 10 mm nominal mortar joints
  5. University of Babylon, Methods of construction and estimation, lecture 14: mortar is about 0.22 m³ per m³ of brick masonry; dry materials shrink by about a quarter when mixed; bulk weight of cement 1,400 kg/m³
  6. EN 12620:2002+A1:2008 clause 3.8: fine aggregate is the sizes with D up to 4 mm
  7. Virtual Labs (IIT Delhi): bulking of fine aggregate: damp sand bulks most at 4–6 % moisture, so volume batches need correcting
  8. NPTEL (Indian Institutes of Technology), soil mechanics worked examples: dry sand about 1,600 kg/m³
  9. US Office of Surface Mining (OSMRE), lime products, citing the National Lime Association: hydrated lime bulk density 3.34 lb/gal, about 400 kg/m³
  10. Quantities for brickwork (MOT, Museum for Old Techniques): allow about 10 % loss for site-mixed mortar
  11. EN 998-2 Specification for mortar for masonry: masonry mortar
  12. EN 13139 Aggregates for mortar
  13. ASTM C144 Aggregate for masonry mortar; ASTM C270 Mortar for unit masonry
  14. EN 197-1 Cement; EN 459-1 Building lime

How the amounts are worked out: wet mortar is 22 % of a 102.5 mm brick wall (University of Babylon) and, from the joint sizes, about 7 % of a 100 mm wall of 440 × 215 mm blocks. Dry volume is a third larger than wet. That is split 1 : 1 : 6 by volume, with loose bulk densities of 1,400 kg/m³ for cement, 400 kg/m³ for hydrated lime and 1,600 kg/m³ for sand, and 10 % is added for losses (MOT).

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