There are many types of concrete screeds out there these days, but which is the best concrete screed for pouring flat projects like parking lots, driveways and floors? And which is the best concrete screed for the type of pours that your company does most often? We’ll break down the pros and cons of each screed, but first, let’s talk about what a screed is, what it does, and why they are necessary.
What is a Concrete Screed?
In a nutshell, a concrete screed is a straightedge tool that is used to level and smoothen the surface of freshly poured concrete. They can be powered by gas, electricity, hydraulics or pulled by hand. They typically made of aluminum, magnesium or steel – though there are exceptions. Screeds ensure that the concrete surface is left smooth, flat and free from any deformities or gaps.
Concrete forms are usually used around the outside edges of the pour. These forms keep the wet concrete contained until the concrete has set hardened. Most concrete screeds use these forms as a guide when leveling or “striking off” the surface of the recently poured slab.
Why is it Important to Screed Concrete?
Screeding is a highly important process when pouring flatwork projects like driveways, floors or parking lots. A contractor that doesn’t cut any corners can pour strong, beautiful slabs that will last for decades to come. As a screed passes over of concrete, it levels the surface of the concrete. Most screed either vibrate or spin – working larger aggregate down, just below the surface. This leaves smaller sand and cream (a thin slurry of cement) on the surface that finishers can work with to build a smooth, professional-looking finish.
How does a Slump Test Factor in?
One of the most important factors in the strength and longevity of a concrete slab is the slump at which it is poured. A concrete slump test is a simple measurement of how much water content is present in relation to the concrete’s other ingredients – aggregate and cement. A low slump has relatively low water content and a high slump has relatively high water content.
Concrete’s water content (at the time of pouring) is directly related to its strength. The wetter the concrete is poured (or high slump), the weaker the concrete will be. While water is essential to the curing process, it is destructive in excess amounts. At the University of Illinois, the Department of Materials Science and Engineering found that “too much water reduces concrete strength, while too little will make the concrete unworkable”. The problem that many contractors face is that wetter concrete is easy to place. So they find themselves cutting corners – making their finisher’s job easier, but sacrificing the strength and durability of the slab.
Pouring at a high slump doesn’t just damage the integrity of the slab – it can also damage a contractor’s reputation and their hopes for future business.
What are the Different Types of Concrete Screeds?
Concrete contractors are responsible for deciding what is the best concrete screed type for their company or for a particular pour. There are many different types of concrete screeds available on the market and each one has its place.
- Screed Boards
- Stand-Up Screeds
- Roller Screeds / Spinning Screeds
- Truss Screeds / A-Frame Screeds
- Laser-Guided Screeds
- Dragon Screeds
Let’s start with the simplest, cheapest option for screeding concrete – the good ole screed board. Generally made from a nice sharp 2×4, a screed board is the simplest solution for screeding concrete – just don’t try to do too much with it. Screed boards operate with one person on each end. They work together to push and pull the board back and forth in a sawing motion while maintaining continuous pressure forward. Choose a board that is straight. If your boar is warped, your concrete will reflect that by leaving either a crown or rut in your slab.
Screed boards are sufficient for short, narrow flatwork projects like small sidewalks or patios. Anything larger than that and you’ll find yourself working way harder than you want to. Bending over while making a sawing motion and trying to pull the screed board all at the same time will wreak havok on even the toughest finisher’s spine.
Another great tool to have on hand, stand-up screeds work wonders on very small pours and in tight areas. Typically set up as a vibrating bar that is operated by a single user, stand-up screeds require one worker to drag the screed while several others are in the concrete, raking as close to grade as they can get. Stand-up screeds are readily available and easy to find on the cheap. They still require a fair amount of physical labor and are limited by width, slope, slump and speed.
Roller Screeds / Spinning Screeds
Roller Screeds or spinning screeds allow concrete crews to get into small areas with ease. Typically set up as a metal tube that spins away from the operators, roller screeds work reasonably well on small pours. They allow crews to pour on steep grades or even use contoured rollers to pour gutters.
Two laborers pull against the spinning screed and the other laborers grade the concrete by hand in between them. Since roller screeds are human-driven, they require a great amount of physical labor. If you’re pouring anything more than a truckload or two, roller screeds quickly become a lot of work to operate. Roller Screeds are powered to spin, but leveling the concrete comes down to brute manpower.
When concrete is left too high, or is poured at a low slump, roller screeds have a tendency to throw concrete over the top of the screed. In this case, the two pullers have to carry the screed back and screed that section of concrete again.
Although the spinning effect of a roller screed has some cream-creating abilities, there is no vibration in roller screed systems. Vibration is key in allowing the aggregate to settle, bringing a small amount of cream to the top.
Lightweight, affordable and easy to clean, roller screeds are an option for tight areas and small pours. Being human-driven, roller screeds require a lot of labor to pull the screed and rake concrete.
Truss Screeds / A-Frame Screeds
Capable of pouring concrete at widths all the way out to 60+ feet, truss screeds or A-frame screeds can put a lot of concrete down – if you have a crew large enough to help drag. Truss screeds are generally gas-powered and are pulled with a winch that is attached on both ends of the screed.
Truss screeds are very heavy and require a lot of labor to set up, tear down and clean. They run relatively slowly and if you happen to leave the concrete a little low in one spot, setting the screed back to strike off again is extremely difficult. You’re generally better off fixing any mistakes by hand. Truss screeds require a lot of laborers keeping the concrete close to grade in front of if – and those laborers work hard for every inch.
Laser-guided screeds are great for jobs that require high flatness specifications. Set up as a laser-guided arm on a relatively small machine, they’re capable of precision level concrete with minimal labor. Crews get concrete somewhat close to grade and laser-guided screeds will level to a precision grade from there.
But there are downsides to laser-guided screeds too. First, they’re extremely expensive – usually costing from $100,000 to $250,000. Second, the widest laser-guided screeds available on the market max out around 20 feet wide. Nearly none of them are capable of grading the gavel base. Laser-guided screeds also come with a significant cost if they break down. There are a limited number of folks that are capable of repairing them when they do. Keep in mind too that breakdowns almost always happen on pour days – never when the machine is sitting idle. So there is a real possibility of losing a pour if your equipment does break down.
Laser-guided screeds save on physical labor and are extremely accurate, but their cost is far more than most can afford. Many contractors choose to rent laser-guided screeds instead of paying the heavy pricetags associated with buying and maintaining their own.
One of the fastest ways to dump and drag a load of concrete, Dragon Screed is easy to set up and extremely easy to use. Its versatility allows crews to screed gravel and concrete in many different configurations. Dragon Screed levels gravel or sand subgrade quickly and accurately. Crews no longer have to drag gravel in order to have a quality subgrade. Once the gravel is level, simply remove the subgrade panels and switch to the vibrating floats and you’re ready to pour concrete.
Dragon Screed, like a laser-guided screed, requires crews to simply get concrete close to grade and the equipment does the rest. Machine driven, Dragon Screed allows crews to pour stiffer concrete without fighting to get it flat. If you want to screed the concrete a second time, it’s as simple as backing your machine up and driving along the forms again. The vibrating floats work the concrete, bringing cream to the surface and making finishing the concrete a much easier job.
Dragon Screed works in forward or reverse, off of either side of the machine, and can also be configured to work directly in front of the machine. Dragon Screed eliminates the need for draggers in front of the screed, drastically reducing much of the manual labor associated with pouring and screeding concrete. Your crew can focus their energy and attention on finishing concrete behind the screed.
Dragon Screed eliminates the need for draggers (or rakers) in front of the screed, drastically reducing much of the manual labor associated with pouring and screeding concrete (see concrete project profitability analysis). Your crew can focus their energy and attention on finishing concrete behind the screed.
Concrete Screed Comparison Chart
|Operates to Left, Right or Center||★★★||Ø||Ø||Ø||Ø|
|No Dragging Required by Laborers||★★★||Ø||Ø||★★★||Ø|
|Ease of Use||★★★||★||★★||★★★||Ø|
|Screeds 20+ Feet Wide||★★★||★★★||★★★||Ø||Ø|
What do All Good Screeds Have in Common?
All good screeds have one thing in common: they do their job well if they are kept in good condition. Any screed that is bent, dented, has dried concrete left on it, or doesn’t run well, is not going to perform well and the finished concrete will show that. It is important that screeds are kept well-maintained and in good working order. If your beat-up old screed isn’t fast, easy to use and leaves a beautiful, professional finish, then it may be time to consider upgrading your equipment – after all, the finished product is the most important thing to your customers.
*The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement