Block Wall Estimator
Complete wall project list — blocks or bricks, mortar sand and cement, and strip foundation concrete in one estimate. 2026 UK pricing.
Enter above-ground wall dimensions only.
Build Guide
Building a Block Wall
Foundation
Dig a trench to the required depth — minimum 200mm for a garden wall, 450mm for frost protection in most of the UK. Width should be at least double the wall thickness. Pour C20 (GEN 3) concrete and allow to fully cure (minimum 3 days in summer, 7 days in cold weather) before laying the first course.
Install a DPC (damp-proof course) 150mm above finished ground level for any wall touching a structure. For freestanding garden walls, a DPC is still good practice at ground level to prevent rising damp wicking up through the masonry.
Mortar and laying
Mix 4:1 soft building sand to cement for standard garden blockwork. Never use sharp sand for mortar — it produces a harsh, unworkable mix. Add a plasticiser to improve workability. Lay bed joints at 10mm and perpend joints at 10mm. Check every course for level and plumb.
Bond pattern matters for strength. Stretcher bond (half-block offset) is standard for single-skin blockwork. English bond or Flemish bond for solid brickwork. Never have perpend joints aligned vertically across two courses — this creates a plane of weakness.
Piers and stability
Single-skin walls over 1m should have piers (pilasters) at no more than 3m centres. A pier typically projects 100–215mm either side of the wall. For a 440mm block wall, a pier one block wide and one block deep (215mm projection) every 3m gives adequate lateral stability. Coping stones on top shed water and protect the wall from erosion.
FAQ
Common Questions
Standard concrete blocks (440×215mm) with 10mm joints give an effective unit of 450×225mm — 10 blocks per m². Standard bricks (215×65mm) with 10mm joints give 225×75mm effective — 59.3 per m², rounded to 60. Always add 10% for wastage from cutting, breakages and mortar losses.
Approximately 0.02m³ of mortar per m² of blockwork at 10mm joints (single skin). For brickwork: approximately 0.04m³ per m² due to more joints per m². Using a 4:1 mix, 1m³ of mortar requires approximately 0.8m³ (1300kg) of sand and 0.2m³ (200kg) of cement. Our estimator calculates this automatically from your wall area.
C20 (GEN 3) is standard for domestic strip foundations — equivalent to a site-mixed 1:2:4 (cement:sharp sand:aggregate) or 1:5 (cement:ballast) mix. For foundations over 3m deep or near trees: use C25 or consult a structural engineer. Ready-mix is often more economical for larger pours; bagged concrete for small jobs.
Freestanding garden walls generally do not need Building Regulations approval. However, if the wall is over 1m adjacent to a road (vehicle access), is a retaining wall, forms part of a building, or affects drainage, Building Regulations may apply. Structural walls as part of an extension or new building always require approval. When in doubt, contact your local authority Building Control.