Screed is a crucial component in constructing floors for both residential and commercial buildings. It is a leveling compound made from cement, sand, water, and sometimes additives such as fibres or plasticizers. The term ‘screed’ refers to both the material itself and the process of applying it evenly across the floor surface using a specialized tool called a screed board or float. In this comprehensive guide, we’ll explore everything you need to know about screed, from its types and applications to installation methods and common problems.
Types of Screed
There are several different types of screed available, each with its own advantages and disadvantages based on specific requirements. Here are some commonly used types:
- Traditional Sand and Cement (Cement: Sand = 1:4) Screed: Also known as traditional sand and cement mix, it has been widely used due to its low cost and simplicity. However, it requires skilled labor to achieve smooth and level surfaces, making it less popular nowadays.
- Fast Drying Fibre Reinforced Gypsum Screed: This type of screed contains gypsum, fiberglass, and polymers, which make it lightweight, quick drying, easy to install, and suitable for underfloor heating systems. Its primary application is in refurbishment works where speed of construction is essential.
- Liquid Applied Flooring Systems: Liquid applied self-smoothing screeds contain acrylic, epoxy, polyurethane, or latex polymers, providing excellent bond strength, chemical resistance, and flexibility. Due to its self-leveling capability, no additional tools required, thus reducing labor costs.
Applications of Screed
The uses of screed vary depending on the building structure and intended function of the area being constructed. Some common applications include:
- Residential Buildings: Screed is extensively utilized in houses, apartments, and flats to create flat and level floors. It could also be installed beneath tiles, vinyl, carpet, or wooden finishes.
- Commercial Buildings: Screeds play a critical role in commercial constructions, including warehouses, offices, hospitals, schools, and retail spaces. Adequate levels of sound insulation, fireproof qualities, and anti-slip features are imperative here.
- Industrial Settings: Heavy machinery, equipment, and vehicles require solid, durable, and stable foundations provided by screed. Besides, factories, storage facilities, and workshops demand robust screed to prevent damage caused by frequent movements.
Installation Methods
Installing screed follows several steps to ensure optimal outcomes. Below are the general procedures:
Step 1: Preparation
Ensure proper groundwork preparation; remove debris, clean the base thoroughly, and level the subfloor.
Step 2: Mixing the Screed
Mix the screed components according to manufacturer recommendations. Ensure adequate mixing and homogeneity of the final product.
Step 3: Pouring
Pour the mixed screed onto the prepared substrate using a wheelbarrow, skip loader, or pump truck. Spread the mixture uniformly utilizing a hand float, screed board or machine floated finish.
Step 4: Smoothening
Use a finishing trowel to smoothen out the surface, removing air pockets, and ensuring consistency. Make sure to achieve correct thickness, compactness, and levelness.
Common Problems during Screeding Process
Although screening is a straightforward procedure, various difficulties might arise during the project execution. Below are some common challenges faced by contractors and DIY enthusiasts:
- Cracking: Unexpected cracking occurs due to incorrect curing conditions, moisture ingress, thermal shrinkage, or excessive drying shrinkage.
- Slumping: Excessive slump, aka the loss of stiffness, happens due to the addition of too much water into the screed composition.
- Bleeding: Water seepage through the screed causes bleeding, leading to unsightly stains on finished surfaces.
- Shrinking: Thermal contraction or prolonged drying periods cause screed shrinkage, resulting in deformities.
Tips & Tricks for Perfect Screed Application
Here are some suggestions for achieving flawless screeding projects:
a) Select the appropriate screed type to match your requirement.
b) Follow manufacturer guidelines regarding mix ratios, curing temperatures, and working life.
c) Use the recommended tool or technique for smoothing screed, depending on whether it’s a manual, semi-automatic, or automated system.
d) Avoid overworking the screed, especially when the initial set begins, as it may lead to cracks formation.
e) Provide sufficient curing time to guarantee complete hydration and strength development.
f) Maintain an ideal ambient temperature between 5°C – 20°C throughout the entire process to facilitate efficient setting times and minimize potential issues like bleeding and cracking.
In Conclusion…
Screeding technology has come a long way since ancient Roman times, enabling modern builders to construct safe, comfortable, and functional buildings efficiently. By selecting the right materials, adopting best practices, and avoiding common pitfalls, contractors can deliver premium quality services while minimizing risks and saving resources. Remember that every job presents unique challenges, so consult expert advice whenever necessary!