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Achieving Flawless Surfaces in Commercial Construction with Screed Concrete

  • November 26, 2023

Concrete is one of the most used building materials on the market. It’s tough and durable, but with the right adjustment, it can become a smooth, more delicate version of itself.

This smoother type of concrete is called screed, and it serves a very specific purpose in the construction industry.

In this article, we’ll be talking all about screed: what it is, what it does, and how it’s used in construction.

Contents:

1. What Is Screed Concrete?

2. How is Screed Different than Traditional Concrete?

3. 3 Main Types of Screed

4. Specialized Screed

5. Screed Applications

6. Important Characteristics of Screed

7. Benefits of Screed Flooring for Commercial Purposes

8. How to Install Screed

9. Conclusion

What Is Screed Concrete?

Screed concrete is a thin layer of sand, cement, and water laid on top of a concrete subfloor to provide a smooth finish. Screed may also serve as an underlayment for flooring. 

Screed can contain additives, be thinner or thicker depending on the purpose, and be placed at different levels of the flooring construction.

To avoid confusion, it’s important to note that “screed” can also refer to the tool used to create a level surface on poured concrete. It’s dragged across wet concrete to create a smooth surface. Alternatively, a power trowel or concrete power screed can be used for larger jobs that go above minor home improvement.

However, for this article, we aren’t discussing these tools. We will only look into the definition of screed that refers to the material itself.

How is Screed Different than Traditional Concrete?

The most significant difference between screed and traditional concrete is the ratio of ingredients. Screed has less water, and concrete has less cement.

Since screed is dryer, it can be applied in thin layers without slumping.

Concrete contains coarser aggregates, making the end result very bumpy. Screed’s finer aggregates make for a smoother finish.

Another big difference between the two is that screed isn’t applied the same way. Rather than being pumped and vibrated into place, screed is applied using specialized tools like trowels, edgers, pavers, floats, and screed boards.

The process requires a skilled craftsman with experience, not just any concrete worker, and it’s definitely not a DIY project.

3 Main Types of Screed

Screed can differ in terms of its applications and uses in three main ways: 

1. Bonded

When screed is applied directly onto the concrete slab using a bonding agent, this is called bonded screed. 

Bonded screed is usually used where heavy loads are expected, since it offers higher strength and stability. It’s also great for renovations or concrete resurfacing due to the need to cling to the concrete underneath. 

Bonded screed requires multiple thinner layers of screed application.

2. Unbonded

Screed that is applied over a damp-proof membrane is called unbonded screed. This membrane separates the screed from the concrete floor below. 

This version also uses thicker layers of screed, reducing the risk of shrinkage or settlement. Unbonded screed is excellent for when there is a chance that dampness could be a problem, such as when underfloor heating is installed. 

3. Floating

Floating screed is applied as a thin layer of insulation between the subfloor heating and the finishing.

A thin layer of floating screed is used for light loads, and a thicker layer for heavier ones.

Specialized Screed

On top of the three main types of screed, there are specialty versions, which differ by the ingredients added to the mixture itself. 

These specialized mixtures were concocted to mitigate a certain problem or present new applications in which screed may be of benefit. 

Fiber-Reinforced

Fiber-reinforced screed contains metal fibers in the mix to add extra strength. It is used for industrial and commercial applications where heavy loads are expected.

Read more: Commercial vs. Industrial Construction: 7 Differences Between the Two

Polymer-Modified

This specialty screed contains polymer additives to increase strength and durability. It’s most often for outdoor use, such as driveways, or heavy traffic areas, like commercial hallways. 

Fast-Drying

Fast-drying screed contains additives that allow the screed to dry within 24 hours. This type is often administered for commercial flooring. Commercial projects are often under a strict timeline and need expediency. 

Liquid Screed

Also known as flowing screed or wet screed, liquid screed is self-leveling and requires little to no finishing. 

Due to the ease of installation, it’s often used in larger commercial or industrial applications where a wide area needs to be covered. 

Liquid screed must not be installed with reinforcement because it is corrosive to metal. It’s also not suitable for damp or humid conditions. 

Screed Applications

Screed is a versatile material that applies in multiple uses to the commercial sector, such as for:

Flooring

Using screed to create a smooth floor is the most popular usage of this product. This is because commercial floors need to be strong while still looking aesthetically pleasing.

Commercial screed flooring is typically bonded, since it provides a sturdier base that can withstand heavy traffic. 

However, if the floor is below ground level, where moisture is more prevalent, it might be wise to use unbonded screed as an overlay of a damp-proof membrane. 

Pavements

concrete-pavements

When using an external screed, your best bet is to use a fast-drying one. Without the more rapid strengthening of the screed, it may be weakened by present weather conditions.

For example, in colder temperatures, the water content of the screed could freeze and cause cracks. In hotter weather, the water can evaporate faster than it should, resulting in a dusty surface. Wind will do the same. 

Drainage

Due to the dryer consistency of some screed, you can trowel it to form a fall in any area that could benefit from extra drainage. In the commercial sector, this could be beneficial in bathrooms, commercial kitchens, and indoor gardens.

Soundproofing

In areas where noise is an issue, you can install a soundproof membrane under the screed, allowing for invisible noise control.

Underfloor Heating

Floating screed is often installed on projects involving underfloor heating or insulation. The screed is placed over the subfloor, providing another layer of thermal insulation. 

Resurfacing

Screed can be carefully spread over concrete requiring resurfacing, providing a smooth surface where there once was a damaged concrete slab. 

Industrial

Screed used for industrial projects contains an added coarse aggregate to create a thicker layer. This ensures that it is more durable to withstand the harsh industrial environment.

Important Characteristics of Screed

For screed to be high quality, it must possess the following characteristics. 

Thickness

The thickness of the screed needs to be appropriate for each individual project. Different applications will require separate thicknesses. 

The screed must be of the right thickness for the purpose of use and the load it will bear. Failure to apply the necessary thickness can result in weakening, cracking, and chipping. 

Consistency

It is imperative that the screed is dry enough. To check this, contractors must measure the surface residual humidity with a hydrometer. The screed must have the same consistency or humidity throughout the entire surface. 

Compact

Just like traditional concrete needs to be compacted and air-free, screed must be level with no cracks or weak spots. This is ensured with proper installation. 

Finish

All screed will have some type of finish, which is dependent on the flooring being installed or the screed being used. Screed with a reflective finish requires a special product.

Flatness

Screed that is applied must be checked with a straight edge 2 meters long to ensure that it is flat and level throughout the surface area. There cannot be a deviation of 2mm or more in any direction.

Benefits of Screed Flooring for Commercial Purposes

Is it really necessary to place another layer of concrete-type material over a concrete slab? Why would a commercial project consider this, and what are the benefits?

Let’s dig into the many advantages that come from choosing screed flooring for commercial purposes. 

Durability

Commercial structures require stronger floors than those of residential buildings. Screed adds more durability to commercial floors, allowing them to withstand heavy traffic, bear heavy loads, and last for years.

Ease of Installation and Maintenance

ease-of-maintenance-on-concrete

The maintenance of screed flooring is cost-effective due to the durability we just discussed. The strength of these floors requires less maintenance and repairs. 

Adding screed to your floor is fast because of the easy delivery and installation. There are no special cleaning processes or harsh chemicals. To clean screed floors, simply wipe them down or vacuum them.

Slip Resistant

The fact that screed is slip-resistant reduces the risk of slips or falls. This protects employees from injuries, which also means the company will pay less in workman’s comp. It also makes the floors safer for customers, so there is less risk of liability or lawsuits from injured patrons. 

Sustainability

Screed is made from recycled materials and is energy efficient. On top of that, screed contains no toxic residues from chemical adhesives.

Design Flexibility

Screed floors come in a variety of color and texture options. This allows a company to keep its unique commercial style or aesthetic across all surfaces.

How to Install Screed

Now that we’ve discussed the what, when, and why of screed, let’s talk about how it’s installed on the surface of the concrete.  

1. Roughen the Surface

Before you can begin to lay the screed, a few steps must be completed to prepare the area. The first is to roughen the surface of the concrete to allow the screed to grip onto it (also called bonding).

This can be done using a shot blaster, grinder, or scarifier. 

2. Remove all Dust and Debris

The first step will create a lot of concrete dust that must be removed before laying the screed. This is usually done by vacuuming. Additionally, you’ll need to remove airborne particles by sprinkling water over the concrete. 

(Steps 1 and 2 will be skipped for unbonded screed. Instead, a damp-proof membrane is applied for the screed to lay on.) 

3. Apply Bonding Agent

Once your concrete is well-prepared, it’s time to apply a bonding agent to reinforce the bond between the concrete surface and the screed. 

Mix your chosen bonding agent — grout, PVA glue, or SBR — and apply it to the concrete.

4. Create Sections

Next, divide the area into manageable sections using long pieces of wood that are at least as high as the thickness of the screed (which should also be wetted). These boards will ensure the screed is level and compact. 

You should also line the walls with edging foam to protect them when the screed shrinks. 

5. Immediately Apply Screed

After administering the bonding agent, you must work expediently. If you wait too long, the bonding agent will dry and won’t adhere to the screed.

Determine the correct screed thickness for your project and apply it to the surface. Bonded screeds are usually 50 mm or thinner. Unbonded screeds can be between 70-100 mm thick. 

6. Level the Screed

Use a screed tool to level it out. Measure the flatness with a straight edge. You may need to use a leveling compound for dry screed, and it would be wise to use a power screed for large commercial jobs.

However, this step isn’t necessary if you are using self-leveling screed. 

7. Finish the Screed

Finish the screed by dragging a bull float across the top to smooth out imperfections. Allow excess water to evaporate, and repeat the process if you need more than one layer. 

Add texture if applicable. Allow to cure, which takes about a week, and dry, which takes about three weeks. 


Conclusion

As you can see, the possibilities of using screed concrete in commercial construction are vast, and the benefits are numerous. But none of that matters if the screed isn’t installed correctly. 

Professional and experienced craftsmen, such as those from FMP Construction, can ensure that your screeding project will meet or exceed your commercial construction needs. 

Contact us today to request a quote.

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