Calculate
Waterproofing coverage per coat is a quantity instruction, not a promise that one product suits every roof. Customers can accidentally double the order when they multiply a full-system consumption rate by the coat count again. This guide shows how to read the unit before calculating. Sika Pakistan publishes different wording for different products: the Bitumen page gives a two-coat consumption, while the Sika-101h sheet gives a per-coat figure. Those examples demonstrate why the exact product sheet matters; they are not interchangeable systems.
Record the inputs before calculating
Record the exact product, country edition and sheet date, substrate, system, area, number of specified coats, consumption basis and pack size. Identify whether the number is kg/m² per coat, kg/m² for the whole system, or kg/m² per millimetre. Litres and kilograms require the product density to convert. Measure returns and details separately; drains, joints and repairs may need different materials. Have the system confirmed for the actual exposure.
Worked example and formula
Illustrative numbers only. Replace every assumed measurement, price, rate and performance factor with evidence for your situation. A 2026 review date does not turn an example into a current market quotation.
100 m² × 1.2 kg/m²/coat × 2 coats = 240 kg
240 × 1.10 = 264 kg; ceil(264 / 20) = 14 packs
100 m² × 1.2 kg/m²/system × 1.10 = 132 kg; ceil(132 / 20) = 7 packs
The first fictional system needs 264 kg including an assumed 10% allowance, or fourteen 20 kg packs. The second uses the same numeric rate for the entire system and needs only seven packs. These are deliberately invented pack sizes and application assumptions, not Sika instructions. If consumption is quoted per millimetre, thickness must be included instead of treating it as per coat.
Interpret the result correctly
Coverage estimates do not establish substrate suitability, crack treatment, drinking-water approval or the required cured thickness. Do not dilute a product to force the expected coverage. Confirm preparation, curing, weather limits and detailing in the applicable sheet. The paint calculator is useful only as an area/coverage arithmetic aid when its units match; it is not a waterproofing-system selector.
Keep the original measurements, source date, units and assumptions beside the result. Change one assumption at a time to see its effect. A comparison is meaningful only when both options use the same scope. Do not silently combine different test procedures, products, dates or fee bases. Round a purchasing quantity upward only after completing the calculation; retain enough precision for intermediate steps.
Frequently asked questions
Which measurements should I use?
Measure the actual coated surfaces and read the consumption basis from the exact regional product sheet.
Is the example a guaranteed result?
No. Roughness, porosity, thickness and detailing can change consumption; the example includes assumed values only.
What should I check before acting?
Confirm the system with the manufacturer or competent applicator, then compare quotations with the same preparation and details.
Use the result and related tools
Write the consumption basis next to every quotation line. Complete the quantity calculation before rounding to packs. Read the existing plaster and waterproofing guide for broader context.
Sources and review scope
Reviewed 22 October 2026. The examples and arithmetic are original editorial illustrations, not field tests, certified designs, current price surveys or promised savings. Sources support the stated concepts; they do not certify these example inputs. The linked calculators have their own assumptions. These articles address specific decisions and complement the existing calculator guides. No Google search-volume or ranking claim is made.