Concrete floors can be cold, uneven and rough, so placing an underlay for carpet or laminate flooring directly onto the concrete can leave your floor looking and feeling less than perfect. To ensure a smooth and even finish, ready for your final flooring, you should lay a quality concrete screed.

What is Screed and What is Concrete?

Screed is not the same as concrete, although it is made in a similar way to concrete. It’s consistency is much thinner and pours more easily. 

The biggest difference between screed and concrete is that screed is not a structural concrete product. As a result there are differences in the way it is made. Screed uses much finer aggregates to ensure a smoother finish and the consistency of the mix is also much ‘runnier’, for a quick and level pour. 

Concrete on the other hand is structural, and the intended use (such as concrete floor bases, foundations, footings, reinforced concrete for large scale builds) will define the exact ratio and type of ingredients used. Generally concrete requires coarse and tough aggregates. For example screed might use fine sand whereas concrete will need gravel and sharp sand to give it a tougher, stronger and more robust quality. Fibers and steel rebar may also be added to concrete to give it additional strength and longevity.  

Screed is therefore not as strong or durable as concrete, and so should only be used as an internal floor covering, to neaten up the finish, and should never be used for actual construction purposes. It can however be used to cover underfloor heating systems as it is a thermal insulator and will conduct the heat well.  

Screed should be applied in a thin layer over the concrete base as a final coating. To get the right mix of screed for your requirements, contact a professional concrete supplier, like the team at King Concrete, and we’ll advise you as to the best product for your floor. 

Types of Screed

  • Underfloor Screed 

This is a very common use and type of screed. It can be poured over thermal flooring systems to protect the system and conduct heat through to the final flooring. 

  • Floating Screed (Unbonded Screed)

Floating screed is used to cover a layer of insulation. It is usually poured over a damp proof membrane so not directly onto the concrete sub base below.

  • Bonded Screed

A strong adhesive agent is usually applied to the structural concrete, and then the screed is poured on top, so the screed bonds directly with the concrete sub base. 

Laying a Floor Screed

Concrete screed can be poured directly into a sub base containing heating, plumbing or electrical components, or onto a damp proof membrane or bonding agent. It is a quick and simple process as the consistency is very fluid and light so it will quickly cover a floor and fill the form work. In large areas you could opt for a self-leveling screed to make it even easier, or in smaller spaces it can be leveled quickly using a wooden float. 

Screed Curing/Drying Times 

Screed, like concrete, needs time to dry or cure before it can be walked on and before any additional flooring or underlay is fitted on top. 

Screed is much thinner than concrete, so it doesn’t take as long to cure and in some circumstances, if the ambient temperature is right and the screed is thin, it can take as little as 16 hours or as much as 2 days. 

If the area that has been screeded will experience heavy foot traffic, you should leave it as long as possible to ensure it’s final strength. If not, the impact could affect the integrity and longevity of the final floor. 

To be sure you leave the appropriate amount of time, always discuss the curing times with your concrete supplier. The team at King Concrete will be happy to advise as to the minimum amount of time to leave your floor to cure for the highest quality and longest lasting results. 

Screed as Flooring 

In modern interior design, screed is becoming a common final flooring finish, particularly in commercial environments, or high-end residential premises with an industrial theme. 

If this is the case, your screed can be polished or painted to provide a decorative finish. It can even be stamped with a pattern while it is curing to provide a textured finish. For example, some designers may lay wooden planks onto the floor, so when cured, the pattern from the wood is transferred to the screed. 

King Concrete Screeds

For more information about concrete screeds, how to lay a screed, what screed is best for your requirements and how long it takes to cure, contact the experts at King Concrete on 0203 893 2292. We supply quality concrete products throughout London, Croydon, Surrey and Kent, and would be happy to help you get the right products for your project.