When you walk on a beautifully tiled or polished floor, what you do not see is the layer beneath that makes it smooth and long-lasting. That hidden layer is called screed. It is one of the most important steps in flooring, yet it is often overlooked. In this guide, we will explore everything about floor screeding, including its types, uses, installation, advantages, and common questions.
What is Floor Screed?
Screed is a thin layer of cementitious material applied over a concrete base to create a level and smooth surface for floor finishes such as tiles, wood, vinyl, or carpet. It is usually made from a mix of cement and sand, but it can also include additives, polymers, or fibres for extra strength and flexibility.
Unlike concrete, which is designed for structural strength, screed is mainly used for finishing and levelling floors.
Why is Screeding Important?
Floor screeding plays a key role in both domestic and commercial buildings:
- Provides a flat and smooth surface for final flooring.
- Protects the underlying concrete base.
- Distributes loads evenly.
- Helps prevent cracks and uneven surfaces.
- Works well with underfloor heating systems.
- Extends the life of flooring materials.
Without proper screeding, even expensive tiles or wood flooring may not last long.
Types of Screed by Material
There are different kinds of screed based on the mix and additives used:
1. Traditional Sand and Cement Screed
- Made by mixing cement and sharp sand (ratio 1:4 or 1:5).
- Applied manually, compacted, and levelled.
- Use: Common in houses and offices.
- Advantage: Cost-effective and strong.
- Disadvantage: Takes longer to dry.
2. Self-Levelling Screed
- A liquid form of screed that spreads and levels itself.
- Often mixed with polymers for better flow.
- Use: Perfect for thin layers and very smooth finishes.
- Advantage: Quick to apply, excellent for small thickness.
- Disadvantage: Higher cost.
3. Fibre-Reinforced Screed
- Contains polypropylene or glass fibres.
- Reduces shrinkage cracks and improves strength.
- Use: Best for heavy traffic areas like malls, hospitals, or airports.
- Advantage: Durable and crack-resistant.
- Disadvantage: More expensive than normal screed.
4. Fast-Drying Screed
- Modified with special chemicals to reduce drying time.
- Use: Projects with tight deadlines.
- Advantage: Can be ready for flooring within days.
- Disadvantage: Higher cost.
5. Polymer Screed
- Uses polymers for bonding instead of cement.
- Can be applied in thinner layers.
- Use: Where strong adhesion and thin sections are needed.
- Advantage: High strength at low thickness.
- Disadvantage: Requires skilled labour.
Types of Screed by Application
Apart from material, screed can also be classified based on how it is laid:
1. Bonded Screed
- Laid directly on the concrete base using a bonding agent.
- Thickness: 25–40 mm.
- Best for: Areas where high strength is required.
2. Unbonded Screed
- Laid over a separating layer such as polythene sheet or damp-proof membrane.
- Thickness: 50–70 mm.
- Best for: Floors where moisture protection is required.
3. Floating Screed
- Laid over an insulation layer (thermal or acoustic).
- Thickness: 65 mm for homes, 75 mm for commercial floors.
- Best for: Insulated flooring systems.
4. Heated Screed
- Laid over underfloor heating pipes or cables.
- Thickness: 65–75 mm.
- Best for: Modern homes with underfloor heating systems.
Installation Process of Screed
- Base Preparation – Clean the surface, repair cracks, and apply a damp-proof layer if needed.
- Mixing – Mix cement, sand, and water (or use ready-mix screed).
- Application – Spread screed evenly using tools such as straight edges or screed bars.
- Levelling – Compact and level the surface.
- Curing – Keep the screed moist for at least 7 days to prevent cracks.
- Drying – Allow sufficient drying before placing final flooring (time depends on screed type).
Common Problems with Screed
- Cracking due to fast drying or poor curing.
- Dusting if the mix is weak.
- Debonding if the base was not properly prepared.
- Uneven surface if not levelled correctly.
Proper mixing, curing, and following standards can prevent most of these issues.
Advantages of Screed
- Provides a flat and smooth surface.
- Protects flooring and increases its life.
- Suitable for both homes and commercial projects.
- Works well with insulation and heating systems.
- Can be customised with additives for strength or speed.
IS Codes for Screeds
Several IS codes are relevant for floor screeding and materials used:
IS 2571:1970 – Code of practice for laying in-situ cement concrete flooring.
IS 383:2016 – Specification for coarse and fine aggregates for concrete (sand quality for screed).
IS 456:2000 – Code of practice for plain and reinforced concrete (general cement and concrete practices).
IS 9103:1999 – Specification for admixtures for concrete (useful in polymer/fast-drying screeds).
IS 2645:2003 – Integral waterproofing compounds for cement mortar and concrete (important in unbonded and floating screeds).
Conclusion🎯
Floor screed may look like a simple layer, but it plays a huge role in ensuring floors are smooth, durable, and ready for finishing. With many types available – both by material (sand-cement, fibre-reinforced, self-levelling) and by application (bonded, unbonded, floating, heated) – screed can be adapted to any project. By following the right installation methods and British Standards (BS 8204), you can achieve long-lasting, crack-free, and beautiful flooring in your home or workplace.
FAQs on Floor Screeding
Q1. What is the ideal thickness of screed?
Bonded screed is usually 25–40 mm thick, while unbonded and floating screeds are 50–75 mm.
Q2. How long does screed take to dry?
Traditional screed dries at 1 mm per day. Fast-drying screeds may be ready in 3–7 days.
Q3. Can tiles be fixed directly on screed?
Yes, once the screed is fully cured and dry, tiles can be installed directly.
Q4. What is the difference between concrete and screed?
Concrete is for structural strength, while screed is for surface finishing and levelling.
Q5. Is screed necessary for all floors?
Not always, but it is recommended wherever a smooth, durable, and level surface is needed before laying flooring.