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Hollow vs Solid Concrete Blocks: Which to Use and How Many per Wall

Solid concrete blocks are at least 75% concrete by volume; hollow blocks have cavities, so they are lighter and suit infill walls in framed buildings. Use solid blocks below plinth, in compound walls and in load-bearing walls unless your engineer specifies otherwise. About 108–116 blocks with a 400 × 200 mm face cover 100 sq ft of wall.

Hollow and solid blocks compared

Hollow and solid concrete blocks compared
Hollow concrete blockSolid concrete block
Definition (IS 2185 Part 1)Has cavities; solid material between 50% and 75% of the block's volumeSolid material not less than 75% of the block's volume
Common sizes400 × 200 mm face; 100, 150 or 200 mm thick (sold as 4, 6 and 8 inch)400 × 200 mm face; 100, 150 or 200 mm thick (sold as 4, 6 and 8 inch)
WeightLighter per block; less load on beams and slabsHeavier per block
Typical useInfill and partition walls in RCC-framed buildingsWalls below plinth, compound walls, load-bearing walls
Fixing shelves and grillsNeeds anchors suited to hollow masonry, or filled cavitiesHolds screws and anchors much like brick
Electrical conduitsCan run through the cavitiesChased into the face
Below groundOnly with cavities filled, as your engineer detailsYes
Our sourceFactories in Gummidipoondi SIPCOTFactories in Gummidipoondi SIPCOT
Our price, 6 inch₹43.85 per block₹44.85 per block
Verdict: hollow blocks for upper-floor infill and partitions where weight matters; solid blocks for foundations, plinth walls, compound walls and load-bearing walls. If the drawing names a block grade or strength, that overrides both rules.

Next question: How many blocks for my wall? About 108–116 per 100 sq ft; the next table scales it. Read

Blocks per 100 sq ft and per wall

A 10 by 10 foot wall, 100 square feet, laid with 400 by 200 mm blocks in running bond needs about 108 to 116 blocks10 ft × 10 ft (3.05 m square)100 sq ft of wall≈ 108–116 blocks400 × 200 mm face,10 mm jointsSame count for 4, 6and 8-inch blocks
100 sq ft of wall in 400 × 200 mm blocks. Thickness changes the wall, not the number of blocks per square foot.
Block count by wall area (400 × 200 mm face, 10 mm joints)
Wall areaBlocksWith 5% for breakage
1 m²≈ 11.6–12.5≈ 12–13
100 sq ft (10 × 10 ft)≈ 108–116≈ 113–122
300 sq ft (a 30 × 10 ft wall)≈ 324–348≈ 340–366
600 sq ft (100 ft × 6 ft compound wall)≈ 648–697≈ 680–732

The lower figure is for blocks that are a full 400 × 200 mm plus a 10 mm joint; the higher one for blocks made 10 mm undersize so block plus joint is 400 × 200 mm. Measure a block from your load to know which you have.

Concrete blocks for a wall · results
ItemTypical quantityIn loads / units
Results appear here (JavaScript is needed for the calculator).

Typical estimate: 11.6 blocks per m² for a 400 × 200 mm face with 10 mm joints (12.5 for 390 × 190), plus 5% for breakage. Thickness (4, 6 or 8 inch) does not change the count.

Next question: How much sand for block mortar? Block walls have fewer joints than brick walls; use M-Sand or P-Sand in 1:6 mortar. Read

Where each block fits in a house

  • Below plinth and plinth walls: solid blocks, or as detailed, because they sit in damp ground and hold back the fill.
  • Ground-floor outer walls: solid or hollow, as your engineer specifies for the frame.
  • Upper-floor infill and partitions: hollow blocks reduce the dead load on beams.
  • Compound walls: solid blocks stand up better to knocks from vehicles and gates.
  • Kitchen and toilet walls: solid blocks where heavy fixtures and wall tiles hang on the wall.

Next question: Bricks or blocks? Blocks build faster with fewer joints; bricks suit small walls and exposed work. Read

Block prices and delivery

Block prices at our yards, before GST and delivery
ThicknessHollowSolid
4 inch (100 mm)₹31.85 per block₹42.85 per block
6 inch (150 mm)₹43.85 per block₹44.85 per block
8 inch (200 mm)₹47.85 per block₹57.85 per block
100 sq ft of 6-inch wall (about 108 blocks)₹4,740₹4,840
Stock items: Factory-direct wholesale prices — usually lower than retail dealers; final price negotiable on quantity.

Blocks come direct from factories in Gummidipoondi SIPCOT and are held at our six stock yards. We deliver from the nearest yard that holds the size you need, so tell us the thickness (4, 6 or 8 inch) and the count.

Next question: What will the load cost delivered? Send the count, size and site location. Read

Questions buyers ask

Questions buyers ask

How many hollow blocks for 100 sq ft?

About 108–116 blocks with a 400 × 200 mm face, plus about 5% for breakage. The count is the same for 4, 6 and 8-inch blocks because only the face size matters.

Which block is best for a foundation?

Solid concrete blocks, or the masonry your engineer details. Hollow blocks below ground need their cavities filled with concrete as shown on the drawing.

What are the disadvantages of hollow blocks?

They need suitable anchors for heavy fixings, chasing can break into the cavities, and they should not go below ground unfilled. Quality varies by factory, so check edges and ask for the strength result.

What is the difference between hollow and solid blocks?

A solid block is at least 75% concrete by volume (IS 2185 Part 1); a hollow block has cavities, with between 50% and 75% solid material. Hollow blocks are lighter; solid blocks hold fixings better and suit walls below plinth.

What is the size and price of solid blocks in Chennai?

The common sizes are 400 × 200 mm on the face and 100, 150 or 200 mm thick, sold as 4, 6 and 8-inch blocks. Our 6-inch solid block, before GST and delivery: ₹44.85 per block.

Need Solid Concrete Blocks in bulk?

Send the material, quantity and site location. Our sales desk in Gummidipundi calls you back within 15 minutes during desk hours to work out a delivered quote and a dispatch slot.

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