Liquid Screed

All You Need To Know About Liquid Screed

Liquid Screed is a new and increasingly popular method of screeding a floor. It creates a supremely level, even and smooth surface on which to lay the final decorative flooring finish (carpet, timber, laminate, ceramic tiles, vinyl). Here we explore all those frequently asked questions when it comes to Liquid Flow Screed.

Here at CES, we supply a range of screed pumps to hire or purchase. If you’re intrigued to learn a little more about what a screed pump is and how it can help you, take a look at this article. >

What Is Liquid Screed?

Liquid screed, also known as flow, pumpable, self-levelling or self-smoothing screed comes ready-mixed and is machine pumped over the existing concrete subfloor. Due to its flowing liquid consistency, it will fill all available space and find its own level which is therefore perfectly straight. Since floors should not vary more than 5mm across a 3m space, cement-based flowing screed is the perfect solution to level out these slightly uneven areas. Flow screed works incredibly well with underfloor heating as it beautifully encases the heating pipes enabling very efficient heat transfer. It is worth noting that liquid screed is not structural and whilst incredibly strong, it is not a wearing surface and should always be finished with flooring panels or tiles.

What Is Liquid Screed Made From?

Flow screed has similar properties to concrete in that it is a mix of aggregates, cement and water. However, concrete is much coarser in texture since it is predominately used for strength. Screed uses a much finer aggregate because its primary purpose is to achieve that even, flat and smooth flooring surface. There are two types of liquid screed, cement-based screed or calcium sulphate screed. The latter is also known as anhydrite screed in which a binding agent of calcium sulphate is added in place of cement. When water is added a reaction occurs in which gypsum is then formed. This reaction will continue for approximately one week until the calcium sulphate is used up. Unlike traditional screed, liquid screed cannot be self-mixed and is delivered to your site ready-mixed.

What Are The Advantages Of Liquid Screed?

There are a great many benefits that are encouraging the industry to turn to using liquid flow screed. Below you’ll find an overview of the advantages but you can read more on this here>

1. Firstly, it is rapid-20mins to lay 25m²/ onsite pouring of 2000m² per day
2. Secondly, you save on costs in labour and time
3. Next, you save on materials since it lays as thin as 35mm (of course materials can vary)
4. It is incredibly effective working alongside underfloor heating and allows easy heat transfer
5. It’s VERY level – no amount of experience can match the science of liquid levelling
6. It is less susceptible to shrinking, therefore, needs fewer expansion joints
7. It won’t curl, crack or warp
8. It is known as the ‘green floor’ due to its eco-friendly credentials
9. Finally, it is laitance free so you don’t need to sand the finished surface

Whilst costings can vary from product to product, liquid screed costs approximately £21.50* per m² however the more screed you are laying the cheaper the cost since you will not be paying part-load charges. This is how much the cost can reduce when pumping larger volumes.

• The typical liquid screed cost for 2000m² would be around £10/m²*
• For 100m² it would be in the region of £16/m²*

With liquid flow screed arriving pre-made, it is useful to find a local supplier to you. As we are based in Buckinghamshire a local company such as RB Liquid Screed or UK Screeds LTD would be a good suggestion.

*Prices correct as of May 2022.

Liquid Screed Vs Traditional Screed

Traditional dry screed has been widespread for many years and is a cost-effective but labour-intensive method of screeding. Dry screed is made up of sand and cement (3-5 parts aggregate to 1 part cement) and is mixed by hand. This mixture forms a thin concrete-like substance that clumps together when squeezed. It is then manually shovelled into place, levelled by a screeding bar or polyurethane float and finally sanded to remove laitance once dry. There is the upside of not relying on outside suppliers for your screed and screed pump when choosing the traditional method however statistics suggest it takes ten times longer not to mention the added drying times. With traditional screed being laid at around 50mm, it can take a minimum of 50 days to dry out before other tradesmen can continue with the project. One benefit of dry screed is that it is suitable for non-flat surfaces that require a gradient such as a wet room. Read more >

How Do I Lay Liquid Screed?

Firstly, as with many products, you should be working between temperatures of 5 and 30 since extreme temperatures will compromise the finish, affecting drying times and the strength of the product. Before beginning also remove dirt and debris. To prevent the screed from drying too quickly an SBR primer or liquid DPM (if grease is present) can be used to eliminate suction. As liquid screed is free-flowing, you should lay a watertight membrane such as a 1000guage polyethene sheet. Remember to curl up this protective membrane at the edges and stick it to the walls as well as keeping corner folds neat and taping any joins. Expansion foam can be used around the edges to allow for movement as the screed expands and contracts.

To achieve the correct level, use a laser level to enable you to set your screed levelling tripods to the correct height by moving the flat plate to the desired level. Once you have set all these elements up, you are ready to pour. Now it’s time for the machine to do the hard work and all you need to do is control the hose as it is pumped. Don’t forget those safety wellington boots as you’ll be wading through the screed. Once poured, you simply need to quickly tamp the liquid with a dapple bar to remove air bubbles and you’re done.

How Thick Should I Lay Liquid Floor Screed?

If you are bonding your liquid screed directly to the concrete subfloor, you should apply a primer to a clean surface. The minimum application would be around 25mm and a maximum of 80mm.

If you are using an unbonded method with a polythene membrane between the concrete base and the liquid screed, you would typically pour a thickness of 30mm (minimum) and no more than 80mm (maximum).

Underfloor Heating And Liquid Screed

Liquid Screed and underfloor heating are perfectly compatible and from a customer’s perspective will save money in the long-term by reducing energy consumption. The reason for this is because the liquid screed flows to completely surround the heating elements ensuring there are absolutely no gaps. This makes for better heat distribution in which only the screed is heated and no energy is wasted heating the concrete subfloor beneath. Since liquid screed is poured as a much thinner layer than traditional screed (around 25-35mm), heat radiates more quickly and evenly, therefore reducing energy expenditure and ultimately saving money. 

When you come to pour your liquid screed, ensure you secure the underfloor heating pipes inside the polyethene with clips every 400mm. It is also good practice to fill the pipes so they are not squeezed by the screed. It is important to follow these steps so that your pipes don’t float upwards when you are pouring.

Liquid Screed Machines

Liquid screed must be machine applied which has its benefits in saving you from back-breaking shovelling, levelling and sanding. A screed pump will ensure your material is thoroughly mixed to the correct consistency. It is tricky to achieve the same level of uniformity by hand plus of course, it saves time and energy in these manual intensive processes. Using a screed pump also allows greater accessibility, since your hoses will pump the material direct to the correct location rather than you shuttle running screed back and forth. 

At CES we specialise in screed pump hire as well as offering flow screed pumps for sale. We stock a variety of screed pumps from brands such as Euromair and Putzmeister. If you’re searching for a compact electric pump to try out that new liquid screed, why not take a look at the Euromair MixPro 28. Alternatively, the Euromair X-PRO D140 is a heavier-duty diesel machine for those larger-scale projects. Our specialist team will be able to help you pin down the right pump for you and your project so why not give us a call. And when you’re ready to pump check out our tips for achieving great results with floor screed. 

Euromair MixPro 28

£6,495.00*
(exc. VAT)

Euromair X-PRO D140

£21,950.00*
(exc. VAT)

Euromair X-PRO E100

£11,500.00*
(exc. VAT)