Screeding is the art of skimming freshly poured concrete floors and other surfaces. It is the first step in the concrete finishing process. The skimming device is called a screed. A good screeding job should leave a surface uniformly flat between two guides without any low spots or holes. Time is of the essence. A good screeding job should also leave plenty of time to float the surface and complete the finishing process before bleed water reaches the top of the pour.
A screed can be as simple as a wooden two by four or as intense as a motorized, vibrating and oscillating machine. Your screed will depend on the size and complexity of your project.
Hand screeds are effective on pours up to 18 feet wide. A screed made from a wooden two by four screed can be improved by wrapping it in sheet metal. This will help the screed leave a smooth surface behind. Commercially available magnesium screeds will have similar qualities. Screeds with ergonomic handles are best for extended use periods and fine hand control. Either way, your hand screed needs to be at least 12 inches wider than the maximum distance between the guides.
Roller screeds are useful for large and small projects where more accuracy is desired. They can be used on level and sloped floors. They are also useful for maneuvering around a form with obstacles. Some roller screeds can produce special features like gutters.
Vibrating Truss Screeds
Vibrating truss screeds are also useful for large and small projects. They are ideal when precision is a requirement of the screeding process.
Motorized screeds are ideal for larger more complicated projects. They can also produce special features like crowns and valleys. The different types of motorized screeds are vibrating, oscillating, and roller. They save time, labor and can simplify more complicated concrete pours.
Screeding should begin as soon as possible after the concrete is poured. Work your way downhill, if applicable, drawing excess concrete into low spots and holes.
When you’re hand screeding, use a sawing motion across the guides as you creep forward along the guides. If the smooth surface begins tearing then your travel along the guides is too fast. Maintain the level of concrete ahead of the screed from ½ to 1 inch above the bottom edge of the screed. This will ensure getting it right on the first pass. Continue making passes along the form until there are no holes or low spots on the surface. Waves and other minor defects can be addressed during the float step of the finishing process.
Most equipment rental stores carry screeding equipment. Incorporating a vibrator will simplify the process and produce finer results. Make sure the concrete you are using is a low-slump type and that your guides or forms will handle the static forces of wet concrete plus some bumping around from people and equipment. Thoroughly walk yourself through the entire form system and have a plan in advance of the concrete delivery. This will speed along the screeding process and increase your safety.
Screeding is a simple art producing concrete results.