Most levelling compounds are supplied as a 'cementitious' (cement-based) powder, ready for mixing with water.

A common bag size is 25 kg.

The coverage rate is sometimes shown in square metres per bag when spread at a particular thickness. For example, the bag might state:

     Coverage: 13 m² at 1 mm thick per bag

Alternatively, it might be expressed as the number of kilograms per square metres at a given thickness, such as:

     Coverage: 2 kg/m² at 1 mm thick

Example

Say you are going to install a cement-based levelling compound on the floor shown in this plan. The compound comes in 25 kg bags and the coverage for each bag is listed as: 13 m² at 1 mm thick per bag.

You have estimated that the average thickness required will be 3 mm. How many bags will you need?

Step 1: Find the area

In the previous lesson we calculated the area of this floor plan as: 11.35 m²

Step 2: Find the coverage for the given thickness

The manufacturer has nominated a coverage of 13 m² for one bag (25 kg) when spread at an average thickness of 1 mm. Therefore a 1 mm thickness will require:

11.35 ÷ 13 = 0.9 bags

Step 3: Find the number of bags

Because you have estimated that your average thickness will be 3 mm, you'll need to multiply the Step 2 figure by 3:

     0.9 x 3 = 2.7 bags

If you wanted to know how many kilograms of compound this represents, simply multiply the number of bags by the kg per bag:

      2.7 x 25 = 67.5 kg