Concrete is a material that has been used for centuries. It's the perfect building material because it can be molded into any shape. But how do you screed concrete? That depends on what type of concrete floor that needs to be done, and what other materials are being used in the project. This post will explain how to screed concrete, what materials are needed, and some best practices you should follow when doing so.
What does screed mean?
Before we begin, it is utterly important to understand the various meanings of the word 'screed'.
The 4 different meanings of the word are,
1. The act of firming or leveling gravel, sand, or concrete with a board
2. A board used to plane the layers of concrete to the required level.
3. The material that has been leveled
4.A thin material that is applied over structural concrete and under the finishing material
Screeding is a term used in construction, particularly masonry, and screed boards are often made from wood. Screed is applied to a concrete surface or mortar for leveling purposes.
In this article, screeding would mean the act of leveling and screeds would represent the board used to plane layers of fresh concrete slabs.
Why should we screed concrete?
Screeding is used for leveling off any irregularities in the surface of the prepared base. Screeding is done in conjunction with thin cement mortar, underlayments, and other surfacing materials. A screed plate is often made of steel or aluminum. It can be smooth or have teeth to help create an even leveling surface. Screeds can also be used to smooth or level off drywall mud, joint compound, and other coatings.
When screed is properly applied it will provide a flat and even surface for the installation of flooring materials such as ceramic tile or sheet vinyl.
Types of screeding
There are two main types of screeding: wet and dry.
Wet screeding is theprocess of spreading concrete with water to make it more workable. This type of screeding is typically used when there is a lot of concrete to be spread, or when the weather is hot and the wet concrete will harden quickly.
When using wet screeding, it's important to make sure the concrete is mixed correctly. The mix should be thick enough to hold its shape, but it should also be thin enough to spread easily. You should also make sure there is enough water in the mix, but not so much that it will cause the concrete to slump.
Once the mix has been prepared, use a screed board to spread the concrete evenly across the surface. Be careful not to push down on the screed board too hard, or you'll end up pushing the concrete underneath it. Make smooth motions when spreading the concrete, and try to keep it as even as possible.
Materials Needed For Wet Screeding:
- Water Hose
- Concrete Screed
When wet screeding, be sure to keep the concrete wet while you're working. If it starts to dry out, add more water. Also, make sure the screed is level and straight. Use a shovel or leveling board to check the concrete, and use a straight edge to ensure that the concrete is spread evenly.
Dry screeding, on the other hand, is the process of spreading concrete without water. This type of screeding is typically used when there is a small amount of concrete to be spread, or when the weather is cold and the concrete will take longer to harden.
Materials Needed For Dry Screeding:
- Leveling Board or Straight Edge
- Hammer and Chisel (or Crowbar)
When dry screeding, be sure to keep the concrete moist. If it dries out too much, add additional water before you continue spreading the concrete. The trick lies in keeping it slightly wet but not as wet as in wet screeding. Also, make sure that your leveling board or straight edge is level and straight. Use a shovel or leveling board to check for levelness, and use a straight edge to ensure that the concrete is spread evenly.
If there are any bumps or ridges in the concrete, use a hammer and chisel (or crowbar) to smooth them out. Be careful not to press down too hard with the hammer and chisel, or you'll damage the surface of the concrete.
Once the concrete has been spread evenly, let it dry for several hours before using it. Using excess concrete is also not a good practice.
Steps to screed concrete
- Mix the concrete to make sure it is in good condition
- Use a screed board to evenly spread the concrete
- Spread it without water when the weather is cold and use a little bit of water when the weather is hot
- Use a magnesium float to spread and level the concrete
- Trowel it afterwards if needed. You can use a power trowel for this if you have one available.
- After the concrete is spread and slightly dry, use a broom to sweep it gently.
Screeding concrete may seem like an easy task, but there are specific steps that need to be followed in order for the concrete to be leveled and smooth.
Different types of screeds
From here on, screed would represent a cementitious substance made from a 1:3 or 1:4.5 ratio of cement to sharp sand(it is important to know the differences between concrete and floor screeds). It may be used on either a solid concrete ground floor slab or a precast concrete floor unit. On top of the screed, tiles or wood flooring or natural stones can be paved.
- A bonded screed is a type of wet screed that uses cement and water to bond the particles together.
- The mix should be thick enough to hold its shape, but it should also be thin enough to spread easily
- You should also make sure there is enough water in the mix, but not so much that it will cause the concrete to slump
- An unbonded screed, on the other hand, is a type of wet screed that does not use cement to bond the particles together. This type of screeed is used when there is a small amount of concrete to be spread
A floated screed is a type of wet screed that uses a metal or plastic float to bond the particles together. This type of screed is used in places where underfloor heating is present and in places where thermal insulation is necessary.
Now that you know how to screed concrete, it's time to get out there and start spreading some! Remember to always follow the best practices for your project, and be sure to ask a professional from the construction industry if you have any questions. Thanks for reading!
Important terms to know
Bull float - A large, flat tool used to smooth concrete after it has been screeded.
Magnesium float - A metal float that is used to finish the wet concrete surfaces
Screed board - A long, thin board that is used to level and smooth surface the concrete
Straight edge - A straightedge that is used in conjunction with a levelling screed
Trowel - A hand tool with a flat, steel blade on one end and a handle on the other for maneuvering the trowel while smoothing out cement.