Types, components, construction, and uses of floor screed

Floor screed is a layer of material that is applied to a floor base to create a smooth and level surface for the installation of floor finishes such as tiles, wood, or carpet. The purpose of floor screeding is to provide a solid and even foundation for the final floor covering.

Screeds are typically made by mixing cement, sand, and water, although there are also specialized screed mixes available that may include additives to enhance certain properties. The mixture is poured onto the prepared floor base and spread using tools like trowels or straight edges.

Floor screeds serve several key roles, including surface levelling, load distribution, thermal insulation, moisture control and sound insulation.

So what’s next? It is then levelled and compacted to achieve the desired thickness and a flat surface. Find out which type of flooring screeds will be the best fit to your home. Visit insulated floor screed for more information.

Types of Floor Screeds

There are several types of floor screeds commonly used in construction. The choice of screed depends on factors such as the purpose of the floor, the load requirements, the desired finish, and other specific project considerations.

Sand and Cement Screed

This is the most common type of floor screed. It consists of a mixture of cement, sand, and water. It is usually applied in a thickness of around 25-40mm and requires proper compaction and curing. 

Fiber Reinforced Screed

Fiber reinforced screeds contain added fibers, such as polypropylene or steel fibers, which enhance the tensile strength and crack resistance of the screed. These screeds are commonly used in areas subjected to heavy loads.

Polymer Modified Screed

Polymer modified screeds incorporate polymer additives into the screed mixture. These additives enhance properties such as flexibility, adhesion, and resistance to cracking. 

Flowable Calcium Sulphate Screed

Calcium sulphate-based screeds, also known as gypsum screeds, consist of calcium sulphate binder, water, and aggregates. They have excellent flow properties and are suitable for application over underfloor heating systems due to their good thermal conductivity

Self-Leveling Screed

Self-levelling screeds are formulated to flow and settle into a level surface without the need for extensive manual levelling.

Fast Drying Screed

Fast drying screeds are designed to accelerate the drying time, allowing for quicker installation of floor finishes.  

There are also different types of floor screeds depending on the method of installation:

Bonded floor screed – This type of screed is bonded to the substrate and is used in areas where there is a low risk of cracking. 

Unbonded floor screed – This type of screed is not bonded to the substrate and is separated by a damp-proof membrane.

Floating floor screed – This type of screed is not bonded to the substrate and is separated by a layer of insulation.

Materials

Floor screeds are typically composed of a combination of materials that provide the necessary properties for achieving a level and durable floor surface:

Cement – Cement is a primary ingredient in most floor screeds. 

Aggregates – Aggregates are used to bulk up the screed mixture and provide stability. Sand, usually sharp or washed, is the primary aggregate used in floor screed. 

Water – Water is needed to hydrate the cement, allowing it to bind with the aggregates and form a solid structure.

Additives and Admixtures – Various additives and admixtures can be incorporated into floor screeds to modify specific properties. These include plasticizers, fibers, accelerators, and retarders. 

Specialty Binders – In some cases, specialty binders may be used instead of or in combination with cement. For example, calcium sulphate (gypsum) binders are used in gypsum-based screeds, which offer specific advantages like faster drying times and suitability for underfloor heating systems.

Construction Process

The construction process for floor screed involves several key steps. First, the base or substrate needs to be thoroughly cleaned, ensuring it is free of dirt, grease, and loose particles. Proper curing and moisture control are essential. If necessary, a damp-proof membrane can be applied. Next, the screed, either manually mixed on-site or supplied as a pre-mixed material, is poured onto the prepared surface. It is then leveled using tools such as straight edges or power floats to achieve the desired thickness and levelness. After the screed is applied, it requires sufficient time to dry and cure. Following the manufacturer’s recommendations, adequate ventilation and temperature control may be necessary during this stage to ensure proper drying.

The drying and curing process can take several days or weeks, depending on the screed type and environmental conditions.

Applications

Floor screed finds applications in various settings:

Commercial Buildings – It is commonly employed in offices, retail stores, hospitals, schools, and other commercial structures to provide a smooth and even foundation for floor finishes. 

Residential Buildings – Floor screed is widely used in houses, apartments, and condominiums as a base for various flooring materials.

Renovations and Refurbishments – During building renovations, floor screed is used to level uneven floors or to add a new layer on top of existing ones. 

Industrial Settings – Industrial facilities, warehouses, and factories often use floor screed to create a smooth and durable surface that can withstand heavy machinery and traffic.