The walls of a house account for a large share of its weight, cost and comfort. Today, builders choose mainly between traditional red clay bricks, AAC blocks and fly ash bricks. Each has strengths, and the right choice depends on your structure, climate and budget.
| Red clay brick | AAC block | Fly ash brick | |
|---|---|---|---|
| Typical size | Small (around 230 × 110 × 75 mm) | Large (around 600 mm long, 100 to 200 mm thick) | Similar to clay brick, more uniform |
| Weight | Heavy | Very light, roughly a third of brick density | Heavy, similar to brick |
| Heat insulation | Moderate | Excellent | Moderate |
| Speed of construction | Slow | Fast | Medium |
| Mortar | Thick cement mortar joints | Thin joints with block adhesive | Cement mortar, less than brick |
| Environmental impact | Kiln-fired, uses topsoil | Uses fly ash, factory made | Uses industrial waste fly ash |
Why AAC is popular in apartments
Autoclaved aerated concrete is full of tiny air bubbles, which make it light and a good insulator. Lighter walls reduce the load on beams, columns and foundations, which can save steel and concrete in multi-storey buildings. Large blocks also mean fewer joints and faster work, and rooms stay cooler in summer.
Where red bricks still win
- Load-bearing walls in small houses without a concrete frame.
- Areas where AAC is not available locally and transport costs are high.
- Places where skilled masons are used to brick and comfortable with it.
Fly ash bricks: a good middle path
Fly ash bricks are uniform in size, need less plaster because their faces are flatter, and recycle waste from power plants. Quality varies by manufacturer, so check strength and water absorption before buying in bulk.
Cracking: the AAC caution
AAC walls can develop cracks if blocks are laid wet, if the wrong mortar is used, or if junctions with concrete columns and beams are not reinforced with mesh before plastering. Use the manufacturer's adhesive, keep blocks dry and follow their detailing.
Estimate quantities for traditional brickwork with our brick calculator.
Frequently asked questions
Can AAC blocks carry loads?
They are mainly used as infill walls in framed buildings. Load-bearing use requires specific design by an engineer.
Do AAC walls hold nails and wall-mounted TVs?
Yes, with suitable anchors designed for lightweight blocks. Ordinary nails hold poorly.