Choosing The Right Floor Screed For Your Project
When you reach the screeding stage of any project you’re faced with a choice – do you go for an anhydrite liquid screed or a cementitious screed? One offers speed and is ideal for underfloor heating, while the other is a durable solution which is fast and efficient when there’s a large area to cover. If you’re wondering ‘anhydrite vs. cement screed – which should you choose?’ this blog is the perfect starting point.
With a huge number of projects under our belts in the London and Essex areas, the Capital Screeding team works with both flowing anhydrite screeds and advanced cement screeds like Cemfloor virtually every single day. We want to pass our practical experience on to you in order to make your decision simpler and ensure you get the right screed for your job.
How Anhydrite and Cement Screeds Set – The Difference Between Curing and Drying
When you pour a screed, two things need to happen – it has to set (become hard) and then it needs to dry (lose its excess water). The composition of anhydrite and cementitious screeds makes them do this in different ways.
Anhydrite screed sets relatively quickly, allowing for foot traffic in 24-48 hours. This initial hardness comes from a chemical reaction that uses up some of the water. However, a lot of excess water remains trapped in the slab. This water has to evaporate naturally through the surface, which is a slow process – this is the reason for the long drying time. It’s this slow release of moisture that makes it so important to test for moisture before laying floor coverings.
A flowing cementitious screed is designed for speed. The chemical reaction of the cement binder is more aggressive and uses up the water much more efficiently to gain strength. Additives also help it to expel moisture faster as it cures. So, while it also sets for foot traffic in 24-48 hours, the subsequent drying phase is much shorter (it can be as little as 28 days) because the material is designed to get rid of water quickly.
How Anhydrite and Cement Screed Perform on the Job
Choosing between these two screeds is about matching their performance to the priorities of your project. Is speed your main concern? Are you working in a potentially damp area? Here’s how they behave for different applications.
If your priority is speed…Cementitious is often the winner.
While both anhydrite and cementitious screeds are quick to pour, the real time-saver is the drying process. A cementitious screed like Cemfloor will dry out much faster. What this means for your project is that your flooring contractors (tilers, carpenters) can get to work sooner, keeping the entire project moving forward with fewer delays.
If you’re installing Underfloor Heating (UFH)… Anhydrite has a slight edge.
Anhydrite screed has excellent thermal conductivity and flows very thinly, wrapping tightly around UFH pipes with no air gaps. This allows your heating system to respond quickly and efficiently. While modern cementitious screeds are also great with UFH, which is why anhydrite liquid screed is the default choice for UFH installations.
When thinking about final floor finishes…
The gypsum base of anhydrite screed is what gives it such great thermal performance, but it also creates two key considerations when it comes to finishing your floor. Firstly, its gypsum nature means it forms a weak surface layer called ‘laitance‘ as it cures, which must be sanded off to ensure your final floor covering can bond properly.
Secondly, it makes the screed sensitive to moisture. This means it’s unsuitable for areas that will be permanently damp (such as wet rooms or bathrooms) and you must ensure it’s completely dry before laying vinyl, wood, or other non-breathable floors.
A cementitious screed is far more versatile here and can be used almost anywhere, including wet rooms (with the correct tanking system).
Matching the Screed to the Job
Here’s our guide to which screed suits which jobs best, based on our experience on sites across London, Essex and the South East.
1. When to Choose Anhydrite Screed
Anhydrite screed is the popular (and reliable) choice for residential and high-performance heating projects. We recommend it for:
Projects with Underfloor Heating (UFH) – Its fluid nature and high thermal conductivity mean it wraps around pipes perfectly and transfers heat into the room with minimal waste.
Large, Level Residential Floors – For big open-plan living areas, luxury self-builds, or apartments, anhydrite’s low-shrinkage properties allow for a beautifully smooth and level floor over large areas with fewer joints required.
2. When to Choose Cementitious Screed
Flowing cement screed is built for speed and durability. We use it when the project demands:
Fast-Track Schedules – For renovations or builds where the clock is ticking, the fast-drying nature of cementitious screed is perfect. It allows tilers, joiners, and other trades to get on the floor much sooner.
Wet or Damp Areas – For bathrooms, kitchens, and utility rooms where a gypsum-based screed isn’t suitable, cementitious is the reliable and durable choice.
Industrial and Commercial Scale Jobs – This is where cementitious screed really comes into its own. For vast warehouse floors, retail units, or car showrooms, you need speed and power. It can be laid over huge areas rapidly and cures quickly to a high-strength, incredibly durable surface that can handle heavy loads and machinery.
Making the Right Choice, Made Easy
Your choice of screed impacts everything from your underfloor heating performance to your keeping on the right side of your deadline. You don’t have to become a screeding expert to get it right. At Capital Screeding, our practical experience with both systems means we can quickly assess your project’s requirements and offer you the perfect solution. Let us save you the hassle.
