How many beams do I need for a beam and block floor?

Beams are typically spaced at 600mm centres. Divide the floor length by 0.6 and add 1 for the end beam. A 6m long floor needs approximately 11 beams.

How many blocks go between the beams?

Standard 440mm infill blocks fit between beams at 600mm centres (the beam top is about 155mm wide, leaving a 445mm gap). You need enough blocks to span the full beam length.

Do beam and block floors need a structural topping?

Yes. A 65mm structural topping (concrete or sand:cement screed) is applied over the beams and blocks. This ties the floor together, provides a level surface and adds structural integrity.

Do beams need propping during construction?

Most beam and block manufacturers require temporary propping at mid-span during block laying and topping. Props are typically removed after 28 days or when the topping has reached full strength.

What span can beam and block floors achieve?

Standard prestressed concrete beams can span up to 6m for domestic loading. Longer spans require deeper beams or intermediate support walls. Check manufacturer span tables for specific beam types.

TradeCalculator

Floor Beam & Block Calculator — Beams, Blocks & Topping

Calculate beam count by span, infill block count per bay, structural topping and propping requirements.

Floor Length

Direction beams run along

Floor Width

Beam span direction

Beam Span

Price Per Beam (optional)

How We Calculate This

This calculator determines beam count, infill block requirements and structural topping volume for a beam and block ground floor.

The formula

Beam count = Floor length ÷ Beam spacing + 1

Blocks per bay = Beam length ÷ Block length (440mm)

Topping volume = Floor area × Topping depth

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.