Weight of a Cement-Sand Screed and Calculation of the Required Amount

The preferred method for preparing the base for any covering is a cement-sand screed. This method requires significant effort from both beginners and professional construction crews. Efficient, high-quality work helps create a monolithic pour with a water-based mortar, providing the necessary slope for drainage outlets. The disadvantages are cost and time requirements.

A mixture of cement and sand creates a perfectly even, dense surface that does not require further facing operations. In addition, it creates a protective barrier against harmful and hazardous substances: alkalis, fats, mineral oils, organic solvents, acids and excess liquid. The screed has a good level of heat conductivity and, therefore, is well suited for installing internal heating under the floor covering. Another advantage is impact strength, which prevents the base from splitting.

Technological features of the process when pouring a monolithic layer

To create a proper base, the weight of the material must be taken into account. For example, the rough base weighs within 90 kg/m², which means it has considerable mass. At the beginning of the work, it is important to analyze the load-bearing capacity of the structure. A concrete or stone base is the most suitable option.

The process of creating a monolithic layer includes mandatory technological features: the layer thickness should be from 3 cm to 7 cm. If the first condition is not met, the structure will crack. Increasing the thickness is inefficient for economic reasons and is characterized by high material consumption. The approximate weight of 1 m² of cement screed is 22 kg. The table below shows the weight depending on the screed thickness.

A base pour can have the following forms:

• As a bonding component between the wall and the rough base (no more than a 4 cm layer).
• As a separate element (layer — 5 cm).
• As a floating slab separated from the walls and floor by an isolating layer (layer — from 5 to 7 cm).

During the work, each form of cement-sand pouring has technological differences and requires thorough preparation of the base. The general stages of the work process include:

• Installing a system of guides
• Moistening the surface of the base covering
• Mixing the components to obtain a uniform creamy mortar
• Reinforcing the base covering if necessary
• Pouring the mortar over the surface (taking settlement properties into account, it is necessary to pour 1 cm above the guide)
• Compacting the cement mortar and adjusting it to the guide level (it is important to remove excess air)
• Correcting with a measuring level
• Removing the guides and the marks left by them

Calculation of material requirements

Before starting work, it is important to calculate the material requirement. The approximate density of a cement-sand screed in dry or hardened condition is often about 1800-2200 kg/m³, so each 1 cm of layer gives roughly 18-22 kg/m². A 1:4 ratio means the proportion of cement to sand, but the dry component volumes cannot simply be added as 1 m³ of finished mortar: some voids are filled with cement paste and water.

Screeds may also contain plasticizers, polymer and water-retaining additives, fibers and other modifiers. They improve workability, adhesion or moisture resistance, but also change water demand, density and final weight. For an accurate calculation, use the dry-mix instructions or the project mortar composition.