AAC — autoclaved aerated concrete — is now the default walling material for most new RCC houses in Hyderabad. Its sizes are sold in inches but made in millimetres, and its price is quoted per block by some suppliers and per cubic metre by plants. This guide puts all of those numbers in one place.
What Sizes Do AAC Blocks Come In?
AAC blocks are covered by IS 2185 (Part 3). The face size used by most plants supplying Hyderabad is 600 mm × 200 mm, and blocks are made in a range of thicknesses.
| Trade size | Actual thickness | Weight per block (approx., dry) | Blocks per m³ | Price page |
|---|---|---|---|---|
| 4 inch | 100 mm | 7 kg | 83 | 4 inch price |
| 5 inch | 125 mm | 9 kg | 67 | 5 inch price |
| 6 inch | 150 mm | 11 kg | 56 | 6 inch price |
| 8 inch | 200 mm | 14 kg | 42 | 8 inch price |
| 9 inch | 225 – 230 mm | 17 kg | 36 | 9 inch price |
| 10 inch | 250 mm | 18 kg | 33 | 10 inch price |
| 12 inch | 300 mm | 22 kg | 28 | 12 inch price |
Weights assume a dry density of about 600 kg/m³. AAC absorbs water, so blocks delivered after rain or kept wet before laying weigh more.
How Many Blocks Do You Need?
Per 100 sq ft of wall: 100 sq ft is 9.29 m², and one block's face is 0.6 × 0.2 = 0.12 m², so 9.29 ÷ 0.12 = 77 blocks, whatever the thickness. Add 3 to 5 percent for cutting at openings and corners.
Per cubic metre: 1 ÷ (0.6 × 0.2 × thickness in metres). For 150 mm: 1 ÷ 0.018 = 55.6, so about 56 blocks.
Worked example. An 8 inch external wall, 40 ft long and 10 ft high, with two windows of 4 × 4 ft:
- Wall area: 400 − 32 = 368 sq ft
- Blocks: 368 × 0.77 = 283, plus 5% = about 300 blocks
Which Thickness Goes Where?
In an RCC-framed house, AAC is infill: the columns and beams carry the load and the blocks fill the frame. The thickness depends on what the wall separates.
| Thickness | Typical use |
|---|---|
| 4 inch (100 mm) | Bathroom and toilet walls, shafts, light partitions |
| 6 inch (150 mm) | Internal walls between rooms |
| 8 inch (200 mm) | External walls — the standard outer wall in an AAC house |
| 9 inch (230 mm) | External walls where the drawing calls for 9 inch, matching a traditional brick wall |
| 10–12 inch | Extra-insulated or fire-separation walls; uncommon in houses |
For west-facing external walls, which take Hyderabad's afternoon sun, a thicker block measurably improves indoor comfort, because AAC's insulation scales with its thickness.
Why Does AAC's Light Weight Matter?
AAC has a dry density of roughly 550 to 650 kg/m³, against roughly 1,800 to 1,900 kg/m³ for burnt clay brick masonry — about a third of the weight for the same volume of wall. That has knock-on effects through the whole structure:
- Smaller loads on beams and slabs carrying walls on upper floors.
- Lighter columns and footings, which a structural engineer can design for.
- Faster laying, since one 600 × 200 block covers the face of about six bricks — about twelve in a 9 inch wall, which is two bricks thick.
What Should You Check on Delivery?
- Dimensions: measure a few blocks; length and height should be consistent within a few millimetres.
- Edges and corners: reject blocks with large chips or cracks.
- Uniform colour and texture without large voids.
- Count: blocks are usually delivered on pallets; count a pallet against the invoice.
- Storage: stack on level ground off the soil, and cover against rain.
The Short Version
AAC is 600 × 200 mm on the face; choose the thickness by what the wall does — 4 inch for wet areas, 6 inch for internal, 8 or 9 inch for external. Plan 77 blocks per 100 sq ft plus 5 percent, and use the per-m³ conversion to compare per-block and per-cubic-metre prices on equal terms.
