Understanding Screed:

Screed is a thin layer of cementitious material applied over a concrete subfloor or structural flooring elements. It acts as a smooth, level surface for subsequent flooring installations. Screeds are typically made of a mixture of cement, sand, and water, which can be modified with additives for specific properties. It provides a solid base for floor coverings and helps to distribute heat evenly in underfloor heating systems.

Benefits of Screed over Underfloor Heating:

Enhanced Heat Distribution:

One of the primary advantages of using screed over underfloor heating is its ability to evenly distribute heat across the entire floor surface. The screed layer acts as a thermal mass, absorbing and radiating heat effectively, resulting in a comfortable and consistent warmth throughout the room.

Energy Efficiency:

Screed acts as an excellent heat conductor, allowing the underfloor heating system to operate at lower temperatures while maintaining the desired comfort level. This can lead to significant energy savings and lower heating costs over time.

Reduced Heat-Up Time:

Screed helps to reduce the heat-up time of underfloor heating systems. As the screed layer absorbs and retains heat, it can help to store thermal energy and release it gradually, providing a more rapid and efficient heating response.

Compatibility with Different Floor Coverings:

Screed over underfloor heating is compatible with various types of floor coverings, including tiles, laminate, carpet, and engineered wood. This versatility allows homeowners to choose their preferred flooring material without compromising the efficiency and effectiveness of the heating system.


Installation Process:

Subfloor Preparation:

Before installing the underfloor heating system, it is essential to ensure that the subfloor is clean, level, and free from any debris. Any necessary repairs or leveling should be carried out to create a suitable base for the screed layer.

Installation of Underfloor Heating System:

The underfloor heating system, consisting of pipes or electric heating elements, is installed onto the prepared subfloor. The layout and spacing of the heating elements will depend on factors such as the room size, heat requirements, and the manufacturer’s guidelines.

Application of the Screed Layer:

Once the underfloor heating system is in place, the screed layer is applied over the pipes or heating elements. The screed mixture is carefully poured, spread, and leveled using appropriate tools. It is important to ensure that the screed is of the correct thickness to achieve optimal heat transfer and structural stability.

Curing and Drying:

After the screed layer is applied, it needs time to cure and dry. This process typically takes several weeks, during which the room should be well-ventilated to facilitate moisture evaporation. It is crucial to follow the manufacturer’s recommendations regarding curing time and conditions.

Key Considerations:

Floor Construction:

It is important to consider the structural integrity of the floor when opting for screed over underfloor heating. In some cases, additional floor reinforcement or insulation may be required to support the weight of the screed layer and improve thermal efficiency.

Professional Installation:

While it is possible to undertake the installation of underfloor heating and screed as a DIY project, it is highly recommended to seek professional assistance. Qualified installers have the expertise to ensure the correct installation of the underfloor heating system, proper screed application, and adherence to building regulations.

Thermostat and Controls:

An efficient underfloor heating system should be accompanied by a suitable thermostat and control system. These devices allow for precise temperature regulation, scheduling, and zoning, providing maximum comfort and energy efficiency.

What Is Screed Floor?

Screed is a type of mortar, commonly used for flooring, and has a smooth texture. It is less coarse than concrete and can be used for numerous tasks, including installing underfloor heating systems. Screed is often made from fine grains of sand and typically sits above a solid concentrate base. The purpose of screed is to provide a smooth top surface so that tiles, carpet, laminate, or wood flooring can be installed.

Screed’s smooth properties make it ideal for use as the upper section of flooring. In many floor installations, screed is placed above a concrete slab. The final top layer of flooring, such as laminate, or carpet, can then be situated above. Concrete is made from stronger aggregates and this makes it more durable. Screed is less durable but has a more suitable consistency. This makes it ideal for underfloor heating systems. There are various types of screed available on the market. But the most common types can be categorized as semi-dry screed and liquid screed.

Different Types Of Screed Flooring

It is recommended that you choose the type of screed floor at the same time as the type of underfloor heating system. Planning and ensuring you have the right materials and components can reduce the possibility of problems in the future. Making changes after installation can be problematic and costly. Part of this preparation is selecting the right type of screed to use for securing the underfloor heating pipework. This will ensure the heat can travel through the floor and warm the room effectively.

The two main types of screed are semi-dry and liquid:

  • Semi-dry screed Often known as the ‘traditional’ method, semi-dry screed is the most popular and is made from a mixture of sand and cement. The ratio of the mix is usually 3:1 or 4:1, depending on the requirements of the project. Water is applied to create a smooth consistency. The mixture can then be applied by hand using a trowel or other flat-edged tool and leveling boards. Good accuracy and results can be achieved, but an experienced installer is vital to ensure consistency and quality of the final design. Polypropylene fibers can be added to improve the strength of the mixture.
  • Liquid screed – This type of screed is sometimes referred to as ‘self-leveling’ screed or ‘flowing screed’. It does not require the use of leveling boards and flat-edged instruments. Rather than being prepared on-site or delivered, liquid screen is directly poured onto a concrete surface to the required amount of depth. The mixture fills the surface more quickly than with traditional methods, enabling a fill of up to 1500 m2 to 2000 m2 in a single day. With fast-drying, liquid screed allows the installation of surface carpets, tiles, wood, or laminate more quickly, allowing the project to be completed sooner.

Traditional Floor Screed

Traditional Floor Screed

Traditional sand and cement screeds, also called “dry screeds”, are a mix of coarse sand and cement. The ratio of sand to cement may vary depending on the contractor, but the average is normally noted as a 4:1 ratio mix. It also needs enough water to reach the required consistency without getting so wet that it will produce more than a few drops of moisture when squeezed.

Drying times for traditional types of screed will normally range between five and seven days.

A traditional floor screed will need a minimum of 28 days before the heating can be switched on, and the UFH system should be run at a low temperature at first to let the screed heat up. This assists in completing the cure before the heating is brought up to its full running temperature.

Liquid Screed thickness

Also known as “flowing screeds”, liquid screeds are often considered a faster, more efficient alternative to traditional sand and cement screeds. This is because liquid screed can be supplied to a building project and simply poured into the space it needs to be installed. From there, the compound mix will harden by itself and form a smooth, flat surface. This is why they are often called self-leveling screeds as well.

What Is The Best Screed For Underfloor Heating?

Semi-dry screed is the most common type of screed used for most underfloor heating projects. But this does not mean it is the best. There are times when liquid screed may be more appropriate. It all depends on the nature of your build and the requirements of the development. Semi-dry screeds are typically better for smaller floor surface areas, where a trowel or flat edge tool can be used to smooth the surface. Fast-drying mixtures are available from some manufacturers and allow semi-dry screeds to be applied to more urgent build projects.

Liquid screeds are faster to apply because they can be easily poured directly onto the specified surface area. They do not need pre-mixing with water, unlike semi-dry screeds. The free-flowing nature of liquid screeds means that larger surface areas can be covered in a faster amount of time, and with greater accuracy. And because liquid screed dries faster and is less likely to crack, the underfloor heating system can be used sooner to help dry the flooring. This is useful when manpower is limited and the project must progress to remain on schedule. A liquid screed is also stronger than semi-dry screed, especially when proprietary mixtures are used in construction.

How Do You Screed Over Underfloor Heating?

How Do You Screed Over Underfloor Heating

An underfloor heating system is effectively ‘planted’ inside a screed. The installation of underfloor heating should not be attempted before the room is protected from external elements. It is crucial to install underfloor heating systems and screed correctly. Otherwise, problems can occur, such as cracks in the upper surface. This is especially the case with stone or tiled surfaces.

Other issues to avoid include inconsistent surface levels. Although it is possible to install UFH and screed on a DIY basis, if you are unsure, it is always best to secure the services of a professional underfloor heating systems specialist. Mistakes and substandard heating issues are invariably expensive to remedy.

Before installation of underfloor heating pipework and associated movement joints, it is important to make sure the surface is completely smooth to accommodate the screed. Be sure to select the most appropriate type of screed (semi-dry or liquid) and have a clear idea of the height necessary to maximize heat efficiency.

The underfloor heating piping or cables should not be wound too tightly so that it restricts the flow of water. Instead, popular layouts should be considered, such as linear, serpentine, and spiral. Insulation is equally important and keeps the efficiency of the system high to prevent lost warmth.

Once the screed has been applied over the UFH piping, the ‘commissioning process’ can begin. Do not attempt to walk on the screed until it has completely dried. Instead, wait for the screed to cure before turning on the heating. After the curing process, the UFH system can be switched on to further assist with drying. Once the screed has completely dried and set, floor finishes can be installed, such as tiling, laminate, hardwood boards, and carpets.

How Long Does Screed Floor Take To Dry?

Screeding the floor varies in the amount of time it takes to dry. The type of screed, the size and layout of the flooring, and the commissioning process are all factors to consider. Semi-dry screed takes longer to dry than a liquid screed, which can be walked on within 48 to 72 hours. Often 3 to 4 weeks is the total required drying time. A useful measurement is 1 day’s worth of drying time per every 40 millimeters of height. Keep windows and doors fully closed to keep out the elements until the solidifying process has been completed. You should ensure you do not turn on the underfloor heating system for over one month. This prevents unnecessary cracks from forming. Super fast-drying screeds are available if you are short on time.

Underfloor Heating Systems: The Modern Approach to Comfortable and Efficient Heating

Underfloor heating systems provide a modern and efficient solution for heating our homes. With benefits such as enhanced comfort, energy efficiency, space-saving design, and silent operation, these systems are becoming increasingly popular. By understanding the different types of underfloor heating systems, the installation process, and key considerations, homeowners can make informed decisions to create a warm and inviting environment while maximizing energy efficiency. Experience the comfort and luxury of underfloor heating, and embrace the future of home heating technology.

Exploring Underfloor Heating Pipes: The Backbone of Efficient Warmth

Underfloor heating pipes form the backbone of efficient and comfortable heating systems. With their flexibility, durability, and ability to evenly distribute heat, these pipes play a crucial role in creating a warm and inviting environment. By understanding the different types of pipes, their materials, installation process, and the benefits they provide, homeowners can make informed decisions when considering underfloor heating systems. Embrace the warmth and energy efficiency offered by underfloor heating pipes, and experience the ultimate comfort in your living spaces.

There are two main types of floor heating systems: electric and hydronic.

Electric floor heating systems use electric cables or heating mats that are installed beneath the floor. These cables or mats generate heat when electricity passes through them. Electric floor heating systems are relatively easy to install and can be used in various types of flooring, such as tile, laminate, or engineered wood.

Hydronic floor heating systems, on the other hand, use water pipes to circulate hot water beneath the floor. A boiler or a heat pump heats the water, which is then pumped through the pipes to provide warmth. Hydronic systems are generally more complex and require professional installation, but they can be more energy-efficient and are often used in larger buildings.

Underfloor Heating and Screed Depth

It is especially important to keep to the recommended thickness of a screed layer, as the depth of the pipe determines how effectively the UFH system will distribute its heat. The thickness of the layer also varies, depending on whether you are using traditional sand and cement screed or liquid screed.

Ideally, a traditional sand and cement screed will have a minimum thickness of 65mm and a maximum thickness of 75mm. No matter the measurement chosen, this should be consistent throughout the work to keep the heat distribution the same.

What is the minimum screed depth for underfloor heating?

The minimum screed thickness you should use for warm water underfloor heating systems is:

  • Minimum depth of 65mm for hand-mixed screed
  • Minimum depth of 50mm for liquid screed


Screed over underfloor heating offers numerous advantages, including eScreed-overt distribution, energy efficiency, reduced heat-up time, and compatibility with various floor coverings. When installed correctly, it provides a comfortable and economical heating solution for residential and commercial spaces. Remember to consult with professionals, carefully plan the installation process, and select appropriate materials to maximize the benefits of screed over underfloor heating. Enjoy the luxurious comfort and energy savings that this modern heating solution brings to your living spaces.