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Brick vs Block Walls — UK Construction Guide
Comparing brick and block construction for UK buildings — speed, cost, thermal performance, structural capacity and when to use each.
Side-by-Side Comparison
| Property | Facing Brick | Dense Block | Aircrete Block |
|---|---|---|---|
| Standard size | 215 x 102.5 x 65mm | 440 x 215 x 100mm | 440 x 215 x 100mm |
| Units per m² | 60 | 10 | 10 |
| Cost per unit | £0.40-1.50 | £1.00-1.50 | £2.00-3.50 |
| Material cost per m² | £24-90 | £10-15 | £20-35 |
| Laying speed | 400-500 bricks/day | 100-150 blocks/day | 100-150 blocks/day |
| Area covered/day | 7-8 m² | 10-15 m² | 10-15 m² |
| Compressive strength | 20-100 N/mm² | 7.3-22 N/mm² | 2.9-7.3 N/mm² |
| Lambda value (W/mK) | 0.77 | 1.13-1.63 | 0.11-0.15 |
| Weight per m² | ~120 kg | ~200 kg | ~55-70 kg |
| Weather resistance | Excellent (facing grade) | Needs render/cladding | Needs render/cladding |
Pros and Cons
Facing Bricks
Pros
- + Attractive finish — no rendering needed
- + Excellent weather resistance
- + High compressive strength
- + Wide range of colours and textures
- + Very long lifespan (100+ years)
Cons
- - Slower to lay (60 units per m²)
- - Higher material cost
- - Poor thermal insulation on its own
- - Higher labour cost per m²
- - Heavier — needs adequate foundations
Concrete/Aircrete Blocks
Pros
- + Faster to lay (10 per m²)
- + Lower material cost
- + Aircrete gives excellent insulation
- + Lighter weight (aircrete)
- + Easy to cut and chase
Cons
- - Needs render/cladding externally
- - Lower compressive strength (aircrete)
- - Less attractive unfinished
- - Aircrete blocks are fragile during handling
- - Dense blocks have poor insulation
UK Cost Comparison (2026 Prices)
Cost per m² of finished wall (materials + labour):
| Wall Type | Materials/m² | Labour/m² | Total/m² |
|---|---|---|---|
| Facing brick (half-brick wall) | £30-95 | £35-50 | £65-145 |
| Dense concrete block (100mm) | £12-18 | £20-30 | £32-48 |
| Aircrete block (100mm) | £22-38 | £20-30 | £42-68 |
| Full cavity wall (brick + aircrete) | £60-130 | £55-80 | £115-210 |
When to Choose Each
Choose Bricks When
- External face is visible and appearance matters
- Matching existing brickwork on extensions
- High structural loads (retaining walls)
- Conservation areas requiring brick finish
- Garden walls and boundary walls
Choose Blocks When
- Internal leaf of cavity walls
- Walls to be rendered or clad
- Speed and lower cost are priorities
- Thermal performance is important (aircrete)
- Internal partition walls
Building Regulations
Under Part L 2021, external walls in new builds must achieve a U-value of 0.26 W/m²K or better. A standard cavity wall with brick outer leaf, 100mm full-fill cavity insulation, and 100mm aircrete inner leaf typically achieves 0.22-0.28 W/m²K depending on insulation type. Structural design should comply with BS EN 1996 (Eurocode 6) for masonry.
Related Calculators
- Brick Calculator — calculate bricks, mortar and sand for any wall
- Block Calculator — calculate blocks and mortar for walls
Next up: related pages
How We Calculate This
Frequently Asked Questions
Most UK cavity wall construction uses a brick outer leaf (for appearance and weather resistance) and a lightweight block inner leaf (for thermal performance). The cavity between them contains insulation. This combination gives the best balance of appearance, weatherproofing, insulation and cost.
Yes. Standard 100mm dense concrete blocks cost around £1-1.50 each and cover more area per unit (0.1 m² vs 0.036 m² for a brick). A block wall is typically 30-40% cheaper in materials and labour than an equivalent brick wall because blocks are larger and faster to lay.
Yes, but the external face would need rendering or cladding for weather protection and appearance. Many UK developments use block walls with external render or timber cladding rather than facing bricks to reduce costs. This is common in Scotland and parts of Wales.
Aircrete blocks (like Celcon/Thermalite) with lambda values of 0.11-0.15 W/mK are standard for the inner leaf. For Part L 2021 compliance, you typically need 100mm aircrete blocks plus 90-100mm cavity insulation to achieve the target U-value of 0.26 W/m²K for new-build walls.
Standard UK bricks at 215 x 102.5 x 65mm need 60 bricks per m² (stretcher bond, 10mm joints). Standard blocks at 440 x 215 x 100mm need 10 blocks per m². This makes blockwork significantly faster — a bricklayer can lay 400-500 bricks per day vs 100-150 blocks covering the same area.
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Last updated: April 2026
Verified against UK standards · estimates only, confirm with your supplier.