Are you searching for “screed meaning in construction?” You can understand “screed” as a process and a special concrete material used to create a level, smooth surface for flooring or other applications. It often involves the application of a thin layer of concrete mixture over a subfloor using a screed tool to level it. This process ensures a uniform surface for laying flooring or other finishes. Read this blog to find answers to “What is concrete screed?”, screed concrete mix design, types of screed and more.
What Is Screed Concrete?
You can understand screed concrete as a specialised, thin layer of cementitious material known as a screed, applied over a concrete subfloor to form a smooth, level surface. Typically, screed concrete thickness varies from 25mm to 75mm.
The concrete screed will not include coarse aggregates such as gravel; it will be made of cement, water, fine aggregates (sand with a maximum grain size of around 4mm), and sometimes additives (like polymer materials, mesh, or glass fibers) will be included for better performance.
Screed concrete mix design involves the ratio of 1 part cement to 3-5 parts sand (0-4mm washed sharp sand). The specific mix can be adjusted based on the desired strength, drying time, or other project requirements.
What are the Different Types of Screed Concrete?
There are numerous types of screed options. The following are some major types of screed concrete:
Bonded Screed
The bonded screed is directly applied over the existing concrete surface or other substrate. It creates a strong bond between the screed and the base layer. The typical thickness for bonded screed ranges from 25mm to 40mm. They are ideal solutions for areas with heavy loads or high traffic.
Unbonded Screed
The unbonded screed is separated from the concrete base by a damp-proof membrane. This prevents moisture from rising and reduces the risk of shrinkage or settlement issues., The minimum thickness for an unbonded screed is usually around 50mm. Unbonded screed is commonly used on upper floors or where insulation layers are required.
Floating Screed
A floating screed is laid over an insulation or acoustic layer rather than directly on the concrete substrate. This design is ideal for enhancing thermal or acoustic performance, making it common in floors with underfloor heating or where sound insulation is required. Floating screeds are usually thicker, with a minimum thickness of 65mm, increasing to 75mm for heavily loaded floors. The insulation layer allows the screed to move independently of the substrate, providing flexibility and preventing thermal bridging. Floating screeds are not necessarily more cost-effective, as the additional insulation material and increased thickness may raise costs. Regular maintenance is not uniquely required for floating screeds beyond standard flooring care.
Liquid (Flow) Screed
Liquid or flow screed is a self-leveling, fast-drying option that spreads easily to create a flat surface with minimal manual intervention. It is widely used in large commercial projects and for underfloor heating, as its fluid nature ensures complete encapsulation of heating pipes. Liquid screeds can be applied at thinner depths, often between 30mm and 40mm.
Floor Screed Concrete Installation Process
You can follow these step-by-step guides for laying concrete screed properly, ensuring you achieve the best results.
Surface Preparation
Before laying concrete screed on any surface, you need to prepare it properly. It starts with sweeping the subfloor to remove dust and debris and ensure no contaminants might get in the way. Make sure there are no holes, cracks, or unevenness. Add a damp-proof membrane during this process to minimise the chances of mould or other moisture-related issues.
Screed Concrete Mix Design
Prepare your concrete screed mix by adding 3 to 4 parts of sand with 1 part of cement. This ratio creates a dry mixture that is best for screed flooring. Make sure the mixture is consistent by taking a handful of it (wear gloves) and squeezing it. If it holds together in a firm lump with very little water coming out, your mix is ready to use.
Setting Up Timber Framing for Screed Installation
Proper screed installation involves more than simply pouring and spreading. You’ll need to set up a timber frame to keep the screed contained and prevent it from spilling into unintended areas. Place the frame on the floor and use a spirit level to ensure it’s perfectly level. Lightly wet the timber to prevent it from drawing moisture out of the screed mix.
Pour the screed within the timber boundaries, leveling it after each pour. Carefully move the frame to the next section, ensuring you do not disturb the freshly laid screed.
Concrete Screeding Process
You can lay the mix prepared with the proper screed concrete ratio by following this laying procedure:
- Division of Surface Area: Divide the required surface area into sections. You can use long, even pieces of timber as dividers. It’s a good idea to wet the timber first—this makes it easier to remove once the screed is applied and partially set.
- Lay Concrete Screed: Start applying the screed mix in the section farthest from the entrance of the room. Use a trowel to spread the mix evenly across the surface. Then, use a screed board to level and compact the mix. For best results, it’s strongly recommended to hire a professional for this step.
- Level your floors: If you’re not using a self-levelling screed, you’ll need to level it manually. Take a straightedge and place it over the timber dividers. Push it forward using a side-to-side, sawing motion. This helps to level and smooth the screed layer evenly.
- Repeat the process: Once the first section is complete, move to the next section and repeat the same steps (dividing, laying, and leveling). After all sections are done, carefully remove the dividers and fill any gaps with the same screed mix.
- Float your screed: Before the screed starts drying, check for uneven areas. Use a float to smooth out imperfections and ensure the entire floor is level and even across all sections.
Curing Concrete Screed
The final step is curing the screed to help it set properly. It usually takes a few days. Cover the screeded surface with a polyurethane sheet to keep it moist. Make sure to block off the area so that no one walks on it during this time. Proper curing can help achieve the strength and durability needed to support flooring or further construction work.
What are Applications of Screed Concrete?
The following are the major applications of screed:
House Flooring
Screed concrete creates a flat and stable surface, which helps your final floor last longer and stay strong. Thus, it is very important to lay different types of flooring like tiles, wood, or laminate. Screed also works well as a base for many floor types, including carpet, vinyl, and epoxy coatings.
Underfloor Heating Systems
Since screed concrete can work like a thermal mass that can store heat and spread it evenly across the floor, it can be used along with underfloor heating systems. This makes it a smart choice for residential and commercial buildings where efficient heating is needed.
Renovations
In renovation projects, especially in older buildings, screed concrete helps fix uneven or damaged floors. Bonded screed is often used over the old concrete to create a smooth and level surface.
Terraces and Balconies
Screed concrete gives a strong and weather-resistant base in outdoor areas like terraces and balconies. You can finish with tiles or waterproof layers to make the space both functional and visually appealing.
Different Types of Screed Tools Used During Installation
Hand Screeds
A hand screed is a tool known for its versatility, designed for smoothing and leveling the concrete. They are most commonly used for projects like residential driveways, slabs, etc. Made from materials like aluminum, magnesium, or wood, these tools consist of a straight edge manually applied across the concrete surface. It is known to be a suitable and ideal solution for small projects and areas with difficulties in reaching the power creed.
The length of the hand screed can range from 3 feet to 20 feet in length and often requires physical effort to pull across the concrete. Although hand screed operates significantly slowly, it has an impact on the quality of the finish by achieving a flat surface level. The wooden screed remains a popular choice due to its low cost
Some hand screeds with vibration features help enhance the settling of concrete, which contributes to a smooth surface finish, giving a final touch. It is quite easy to operate and has a less environmental impact, creating a lower risk of injury due to the absence of any moving parts. This makes it a go-to choice due to its cost-effective solution for achieving a smooth concrete surface.
Vibratory Screed
A vibratory screed is an essential tool for leveling and smoothing the process of screed application, which uses vibration. Known for its light weight and durability, it is typically made from aluminum or magnesium. It uses a mechanism consisting of a vibrating unit attached to the screed bar.
Common types of vibratory screeds are
- Truss screed
- Handheld screed
- Roller screed
Using the vibration mechanism helps settle the concrete by removing air bubbles. The usual length of the vibratory screen ranges from 4 feet to 20 feet in length. The major power sources are mostly gasoline, diesel, or electric motors to produce the vibration. It has a frequency range from 3000 to 5000 vibrations per minute, which ensures consistency and is suitable for larger and open areas.
Laser Screed
A laser screed is categorized as a high-tech tool used to level and smooth freshly pour concrete. Laser technology is applied in this process, which consists of a laser transmitter, receiver, and a laser screed head. It serves as an ideal solution for large-scale projects that require higher precision and flatness.
The major types of laser screeds are:
- Walk behind screeds
- Ride on screeds
- Boom screeds
By utilizing a laser transmitter and receiver, precise leveling is always obtained. The typical length of this type of screed ranges from 10 feet to over 20 feet in length. It is majorly designed to withstand heavy use and harsh conditions. Compared with manual screeds, these are heavier and require support for transportation. However ,physical effort and manual labour are reduced by using this, making it more suitable in more open areas and large spaces.
Roller Screed
Roller screed uses a spinning tube to obtain the final level and smooth surface. Its basic design consists of a power source under a rotating table that enables the smoothing process of the concrete. Aluminium or steel are the most common materials used. It increases durability, making it ideal for low-slump and pervious concrete applications.
Major types of roller screeds are:
- Hydraulic screed
- Electric screed
- Gas screed
- Battery powered screed
Roller screeds are generally powered by electric, hydraulic means, and gas. Though it is best for heavy-duty industrial applications, it is also suitable for indoor uses. It stands out significantly due to no emissions. Proper handling is required to reduce the risk of injury as it is machine-oriented. It also releases some noise due to the motor. It is efficient for large-scale projects and requires significant storage space. It produces minimal vibration and reduces operation fatigue. The major applications are commercial floors, large slabs, and parking lots.
Common Issues in Concrete Screed & How to Fix Them
After laying the concrete screed, many people complain, “Why is my screed cracking?” and “How to repair screed concrete?” You can find answers to these questions by understanding the following common problems and finding their respective solutions.
Cracking
Cracks in the screed usually happen if it dries too fast, shrinks too much, is mixed not properly, or is not cured correctly. To stop cracks from forming, keep the screed moist during both laying and curing. Use special screed mixes with additives that help prevent cracks. Also, protect the fresh screed from extreme heat, cold, or wind.
Suitable curing methods, like covering the screed with plastic sheets or use of curing compound, can help to hold in moisture and reduce the possibilities of shrinkage cracks.
Delamination
When the screed gets separated from the substrate, delamination occurs. This can be due to improper surface preparation, excess moisture content, or using the wrong adhesive. To prevent this, ensure the subfloor is clean, dry, and free of dust or dirt before laying the screed. Use the right primer or adhesive, and if needed, do a bonding test before starting. If delamination arises, repair the affected area using proper bonding agents or a new overlay.
Uneven Drying
Uneven drying leads to surface irregularities, curling, or weak spots. This issue often arises from inconsistent screed thickness, poor environmental controls, or high ambient humidity. To address this, maintain a stable curing environment with controlled temperature and humidity, use self-leveling screeds where needed, and test moisture content before laying floor finishes. Moisture barriers or membranes can also help manage drying rates and prevent related problems.
Cost of Screed Concrete per sq ft in India
The cost of screed concrete in India varies considerably based on the type of screed, project size, additives, labor charges, and location.
- A rough estimate for basic laser screed services is usually around ₹30 to ₹50 per square foot.
- Standard laser screed flooring may cost between ₹50 and ₹80 per square foot.
- If you choose high-quality or special types of screed, like epoxy or polyurethane, the cost can go higher — between ₹80 and ₹150 or more per square foot.
Understanding screed in construction is essential for achieving a smooth, level surface in both residential and commercial projects. From bonded and unbonded screeds to advanced types like liquid and floating screeds, each serves specific needs based on load, insulation, and finishing requirements. The installation process, including proper surface preparation, mix design, and curing, plays a vital role in long-term performance. Also, learn the use of various screed tools to achieve perfect finishing. Whether you’re laying a new floor, renovating an existing one, or installing underfloor heating, it’s best to hire a professional construction company. They can ensure proper screed application for a long-lasting and high-quality flooring solution.
Hemali Patel