Floor Screed: Area, Thickness and Volume

Measure the net floor area

Multiply length by width for a rectangle and add distinct floor areas without overlap. The calculator can repeat identical rectangles and subtract one total excluded area across those rectangles. A known net area already includes its deductions and should not be reduced again. Measure different zones separately when they have different specifications or depths. Wall plaster area is not floor screed area.

Convert millimetres to metres

Divide thickness in millimetres by 1000 before multiplying floor area. A hypothetical 40 m² floor at an average 40 mm thickness is 40 × 0.04 = 1.6 m³ installed volume. A chosen 10% extra allowance makes 1.76 m³ of material target. These dimensions and allowance are arithmetic examples, not a suitable thickness recommendation for every floor construction.

Average thickness and uneven backgrounds

A nominal depth may not capture hollows, steps, falls or local repairs. Obtain an appropriate level survey or measured take-off and calculate zones rather than guessing that every square metre has the same depth. Known-volume mode derives an equivalent area from the entered average thickness. That derived area is an arithmetic basis for consumption and labour, not proof that an uneven floor has been surveyed accurately.

Site-mixed sand and cement

The site-mix method applies an entered dry-material factor to adjusted installed volume, splits the dry bulk volume by cement:sand parts and uses loose cement bulk density for mass. It rounds the required mass to the actual bag size. Ratio, factor, density and bag mass must be checked for the specified materials and yield. The defaults are transparent examples and do not design a bonded, floating or unbonded screed.

Sand condition and the meaning of dry screed

Use the specified sand rather than assuming a search term such as sharp sand defines grading, moisture or local suitability. The calculated sand volume uses the entered bulk basis; loose delivery and tonnage require supplier information. A dry-packed sand-and-cement mix is also different from a dry-board floor assembly. The calculator does not estimate floor panels, support layers or proprietary dry-floor components from a cement:sand ratio.

Compare quotes on the same scope

For supplied flowing screed, use volume-only mode and the supplier’s order increment and quote, without assuming cement or sand quantities. For site mix, price full cement bags and sand on the same bulk-volume basis. Labour uses net floor area for the agreed scope. Confirm preparation, primer, reinforcement, joints, pump, delivery and minimum charges separately. No extra VAT is added, so normalise the quote basis before entry. Copy, print or download the result snapshot after calculating.

Frequently asked questions

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