Knowing and having suitable materials is necessary if you’re working on a construction project. In order to complete your project to the required standard, you’ll need to know about every construction material. One likely less common material is screed, which plays a vital role in construction. This article discusses screed, its use, and its importance in construction.
What is Screed?
Screed is a thin coating applied on the top of concrete floors to level the surface and provide a strong base for the finishing floor. It is usually a mixture of sharp sand and cement, but coarse aggregates are sometimes added when a thicker layer is required. The screed layer is covered with decorative tiles or wooden floors, but in some cases, it is left bare, such as in warehouses.
Types of Screed
There are mainly five types of screed.
Underfloor Screed
It is the most common type of screed used to cover insulation layers. It is poured on heating pipes and helps regulate heat flow.
Bonded Screed
Bonded screed uses a binding agent to stick to the concrete floor. It’s very versatile and can be applied to precast planks, beams, concrete, and block floors. Bonded screed is ideal for heavy industries which require a lot of hammering, such as driveways, factory floors, and car parks.
Unbonded Screed
It is not directly placed on the concrete layer; instead, it is separated from the concrete layer by a damp-proof membrane. The purpose of this membrane is to help reduce moisture and shrinkage. Similar to bonded screed, it can be used for underfloor heating.
Floating
Screed can be used as a floating layer of insulation material. The thickness of the floating screed varies depending on the type of floor; for lightly-loaded floors, it will be around 65mm, and for heavily-loaded floors, it will be around 75mm.
Polyurethane and Resin Screed
These are the best options for industrial settings. Furthermore, they can also offer incredibly hard-wearing finish for:
- Medical facilities
- Warehouse and factory floors
- Commercial kitchens
To apply this kind of screeding, radius coves are used. They are available in trowel-applied, self-levelling formulations and poured options.
Resin screeds are famous for levelling damaged cement floors. They have high water, abrasion, and chemical resistance and provide non-slip and safe surfaces.
How is Screed Different from Concrete?
While the chemistry of concrete and screed is not too dissimilar, a few factors separate them.
The key differences are:
- Finishing
- The aggregate’s size
- Consistency of the mixture
- The grade of concrete
The concrete preparation needs a coarser mix than the screed. The bigger and harder aggregates of the concrete give them longevity and durability. Therefore, concrete is the best choice for the industrial areas.
On the other hand, the screed is smoother, using almost half of the aggregates used in making concrete. It is not as durable as cement, which isn’t its primary purpose. It is commonly applied on the top of the concrete layer to make a smooth surface for final finishing.
What is Screed Used for?
Screed is commonly used for levelling uneven concrete floors and making the surfaces more smooth for applying sensitive floor top finishes. Moreover, screed is also the best choice for underfloor heating; it covers the pipes, helping them transport heat more effectively.
Importance of Screed
Screed is an essential part of every construction project. It creates a bump-free, smooth finish to concrete floor surfaces. Additionally, it adds aesthetics to concrete floors and makes sit more durable. The long-lasting and durable top layer protects the floor from heavy things falling and constant use impact. It doesn’t just beneficial for floors but is also very effective for underlying heating systems. It helps provide insulation to the heating pipes ensuring that the heat travels throughout the house properly. The screed is designed to be robust and durable but can be modified to a more long-lasting form when used for industrial purposes.
What Construction Projects Does Floor Screed Work Best for?
Screed can be used in any project with internal flooring but is most commonly found in airports, educational institutes, houses, hospitals, and commercial sites. It is also a great option to soundproof residential buildings; it helps cut down noise transmission.
How is Floor Screed Applied?
Applying a screed is a pretty simple process; you’ll just need a few basic tools. Before starting, calculate the amount of screed you’ll need to cover the area. If you’re buying a prepared screed, an average-sized bag will cover approximately one square meter of the floor with a thickness of 10mm.
Materials and Tools Needed
- A large bucket or container
- A waterproofing product
- Measuring jug
- Paintbrush or roller
- A drilling machines
- Trowel
- Spirit level
- Face mask, eye protection, and gloves
Preparation
If you are going to screed a wet area such as a laundry area, kitchen, or washroom, it is essential to waterproof it thoroughly to avoid the risk of leaking and resulting in long-term damage. You can buy any good quality waterproofing product from a nearby hardware store, and before applying it, clean, wipe down, and vacuum the area completely.
Screeding
- Pour the floor screed mix and water (1:1) into a mixing bucket, and per 20kg of screed add 2 litres of combined liquid.
- Blend the mixture with a drill mixer on moderate speed until it becomes smooth.
- Pour the mixture into your screeding area, and spread it out to a thickness of roughly 10mm. To do this, use a straight-edge, long spirit level.
- Then, make the surface more even and smooth using a trowel or float.
- Once you are done with levelling the surface, let it cure for a minimum of one week. Although the screed will become firm after 24 hours, it will still have moisture, so it is best to leave it for a week.
What is the Drying Time of the Floor Screed?
The drying time of the floor screed depends on many factors, including:
- The thickness of the screed
- Where it is laid
The screed floor must be left for at least 48 hours before walking on it. However, it doesn’t dry completely in 48 hours; the ideal drying time is one week.
Frequently Asked Questions (FAQs)
How Do You Know Screed is Dried?
To test whether the screed is dried, attach a polyethene tape on the floor and leave it for 12-15 hours. Then remove the tape; if the tape has no wet patches but a little moisture, the floor has dried.
How to Decrease the Drying Time of the Screed?
High air flow rate speeds up the drying of the screed as it doesn’t allow moisture-air to stay above the surface of the screed. If air stays longer on the surface of the screed, it carries moisture and stops or slows the drying process.
Do All Concrete Floors Need Screeding?
Screeding on concrete floors isn’t compulsory, but it is recommended to avoid bumpy floor surfaces and make them more long-lasting.
Is Waterproof Screed Available?
Yes, a waterproof screed is accessible and best for applying on wet surfaces. It’s comprised of special additives and aggregates of sand to make it waterproof.
Takeaway
Screeding supports the final flooring layer, so it is essential to get it right. If you want your floor to be stronger and last much longer, choose the right screed, mix and apply it accurately. It will surely add value to your property.