UK Block Types & Specifications
Dense, lightweight and aerated concrete blocks with compressive strengths, thermal conductivity and typical applications.
Common UK Block Types
| Type | Strength (N/mm²) | Density (kg/m³) | Weight (100 mm, kg) | Lambda (W/mK) |
|---|---|---|---|---|
| Dense concrete | 7.3 / 10.4 / 22.5 | 1800–2100 | ~20 | 1.13–1.46 |
| Lightweight aggregate | 3.6 / 7.3 / 10.4 | 1000–1400 | ~12–15 | 0.27–0.50 |
| Aerated (AAC) — standard | 2.9 / 3.6 | 460–600 | ~7–9 | 0.11–0.15 |
| Aerated (AAC) — high strength | 7.3 | 700–800 | ~10 | 0.17–0.19 |
| Trenchblock (AAC foundation) | 3.6 / 7.3 | 460–700 | ~16 (300 mm wide) | 0.11–0.17 |
Standard UK Block Sizes
| Face Size (mm) | Thicknesses (mm) | Blocks per m² |
|---|---|---|
| 440 x 215 | 75, 100, 140, 150, 190, 200, 215 | ~10 |
| 440 x 140 (Trenchblock) | 255, 275, 300, 305, 355 | ~15 |
Where to Use Each Block Type
| Application | Recommended Block | Min. Strength |
|---|---|---|
| Below ground (foundations) | Dense concrete or trenchblock | 7.3 N/mm² |
| External wall — inner leaf | Lightweight aggregate or aerated | 3.6 N/mm² |
| External wall — single leaf | Dense or lightweight aggregate | 7.3 N/mm² |
| Internal partitions | Aerated blocks (75 mm or 100 mm) | 2.9 N/mm² |
| Party walls (separating walls) | Dense concrete (215 mm) | 7.3 N/mm² |
Related Calculators
See the UK Block Sizes for detailed size and weight data, or the Mortar Mix Ratios for correct mortar specifications by block type.
How We Calculate This
Frequently Asked Questions
Related Calculators
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.