Most Indian houses are built with one of four materials: red clay bricks, fly ash bricks, AAC blocks or concrete blocks. Each has its own IS code, and each suits a different job. Here is a quick guide to all the common types.
All types at a glance
| Type | Made from | IS code | Best for |
|---|---|---|---|
| Burnt clay brick (red brick) | Clay, fired in a kiln | IS 1077 | General walls, load-bearing walls |
| Perforated clay brick (3, 8, 10 hole) | Clay, extruded and fired | IS 2222 | Infill and outer walls |
| Hollow clay block | Clay, with large cavities | IS 3952 | Light partition walls |
| Fly ash brick | Fly ash, lime or cement, sand | IS 12894 | General walls, plastered work |
| AAC block | Cement, lime, fly ash, aerated and autoclaved | IS 2185 (Part 3) | Light infill walls in framed buildings |
| Concrete block (solid or hollow) | Cement, sand, aggregate | IS 2185 (Part 1) | Boundary walls, godowns, framed buildings |
| Sand-lime brick | Sand and lime, steam cured | IS 4139 | Walls where an even, light colour is wanted |
| Fire brick | Fire clay | IS 6 | Kilns, furnaces, chimneys, tandoors |
Burnt clay bricks
The traditional red brick, made by moulding clay and firing it in a bhatta. Strength is graded in classes under IS 1077 (class 3.5, 5, 7.5, 10 and so on, by minimum compressive strength in N/mm²). On site, bricks are still often sorted the traditional way:
- First class: well burnt, even red colour, sharp edges, clear ringing sound. Used for exposed and load-bearing work.
- Second class: slightly irregular shape or colour. Fine for walls that will be plastered.
- Third class: under-burnt, pale and soft. Only for temporary work.
- Jhama (over-burnt): dark, twisted and very hard. Broken up and used as brick ballast, not for walls.
Machine-made wire-cut clay bricks have more even sizes and sharper edges, which suits exposed brick walls.
Perforated and hollow clay bricks
Perforated bricks have small holes through them (3, 8 or 10). They are lighter than solid bricks, and mortar keys into the holes. Hollow clay blocks have larger cavities and are lighter still, but are used mainly for non-load-bearing walls. See 3 hole, 8 hole and 10 hole bricks.
Fly ash bricks
Made from fly ash from thermal power plants, mixed with lime or cement and sand, then pressed and cured without firing. They have an even size and a smooth face, and use a waste material. Quality varies a lot between small plants, so check strength and water absorption before buying. See fly ash vs red bricks.
AAC blocks
Large, light blocks made by aerating a cement-lime mix and curing it under steam pressure. Much lighter than clay bricks, quick to lay, and good at keeping heat out. They need thin-bed jointing mortar and a skilled mason, and are mostly used for infill walls in RCC-frame buildings. See AAC blocks vs red bricks.
Concrete blocks
Solid or hollow blocks made from cement, sand and aggregate, commonly 400×200 mm on the face in 100, 150 or 200 mm thickness. They are fast to lay and widely used for boundary walls and industrial buildings. See hollow bricks and blocks and brick vs concrete block.
Sand-lime and fire bricks
Sand-lime bricks are made from sand and lime, pressed and steam-cured. They are even in size and light grey or off-white, but less common in most of India.
Fire bricks are made from fire clay and withstand very high temperatures. They line kilns, furnaces, chimneys and tandoors, and need a refractory mortar, not ordinary cement mortar.
How to choose
- Load-bearing walls: burnt clay bricks of the class your engineer specifies.
- Infill walls in an RCC frame: AAC blocks, fly ash bricks or perforated clay bricks. All reduce weight.
- Exposed brick walls: first class or wire-cut clay bricks.
- Boundary walls: clay bricks or concrete blocks, whichever is cheaper delivered to your site.
Local availability matters most. A material that comes from a plant 200 km away can cost more delivered than a slightly "better" one made nearby.
