Different Types of Floor Screeds

Different Types of Floor Screeds

Beautifying homes and making them look perfect is something many people love to do. We all want our house to be a place that best defines us, and give us the required comfort. In order to design a home according to our style, we need to take into consideration some essential factors such as the wall design, ceiling structure and most importantly the flooring.

Flooring is an essential aspect of home design, as we walk on it. If it is not structured properly, we may tend to fall and hurt ourselves. To avoid such situations, considering your flooring options is vital.

When flooring work is in process, make sure that proper floor screed is utilised. There are different types of floor screeds that can be used. But, before understanding the types, let us see what a floor screed is.

What is a Floor Screed?

Floor screed is an important element, which basically consists of sand and cement, mixed in a ratio of 3 to 5 parts of sand with 1 part of cement. But, in most of the cases, a ratio of 4:1 is sufficient enough to be used.

This screed ensures that a smooth surface is created so as to lay the final flooring product on it. It also sees to it that, the final flooring is in proper level. Floor screeds can be applied on hard concrete floor slabs, as well as on precast concrete floor.

Types of Floor Screeds

There are various ways that are used to apply a screed, at the same time; there are varieties of floor screeds that are available in the market. You can select any of them according to your needs and requirements, and the one that you think is the best.

Here are the types of screed that you need to know:

  • Bonded Floor Screed:

This is one type of screed which is bonded completely to the substrate with the help of a primer or bonding agent. Generally, this screed is an ideal option for thinner sections wherein heavy items are expected to be kept.

It is either made with the mixture of cement and sand or calcium sulphate. If it is made up of cement and sand, then manual levelling and physical smoothening is required. But, if calcium sulphate is used, then it acts as a self levelling screed which requires no manual effort.

Bonded screeds are applied on rough concrete, which is later on bonded with the help of an adhesive such as PVA, SBR or old fashioned cement.

PVA adhesive works really well, especially when mixed with water. SBR is somewhat similar to PVA but, it is not soluble in water once it has dried. Therefore, it is always recommended to use it in wet areas like swimming pools.

Cement is any time a better bonding agent but, it is reasonable to use it only when the screed has a depth of 50mm in between. It is also recommended that, its slurry is to be formed using water and only then it should be applied between the screeds.

  • Partially Bonded Floor Screed:

This screed type can be an affordable alternative for bonded screeds. When compared to other screed types, this comes with an added risk of failing the floor screed.

When used for floors with depth less than 50mm, it tends to break, as with time the concrete is lost.

A partially bonded screed can work well when bonding agents like PVA or SBR are used with it, as these agents prevent the screed from falling.

There are still higher chances of risk that the screed will break and fall, when the screed is laid on the base or slab which is not rough enough to hold it.

  • Unbonded Floor Screed:

As the name suggests, this screed is not directly bonded to the concrete base. Rather, they are purposely separated with the help of DPM i.e. damp-proof membrane.

This screed again is made with a mixture of sand and cement or calcium sulphate. It has the capability of levelling by itself.

A key advantage of this screed is any crack from the sub-base is never taken up through the screed.

The time that it requires to dry itself can be decreased by omitting the concrete’s drying time. It is important to see to it that, while the screed is being used all the walls and pillars are lined with edging foam or 20mm insulation is used to avoid shrinkage cracking.

  • Floating Floor Screed:

Floating screeds are always laid on an insulation, this is because; it provides an insulated floor area.

Even with this screed type, the walls and pillars should be lined using edging foam or 20mm insulation. This protects the screed from shrinkage cracking.

Floating screeds are generally used while building a house, especially when underfloor heating systems are being used.

Similar to unbonded screeds, even floating screeds can be given the same level of rigidness with the use of high-impact insulations.

  • Floor Screed over Underfloor Heating:

This screed is basically a construction wherein a layer of screed is applied or installed over the underfloor heating systems and on top of insulation with separating layers.

While installing this layer, make sure that any debris and other contaminants such as oil or grease are removed to ensure that the surface is clean.

  • Improved Floor Screeds:

The above mentioned were the traditional screed types. Other than these, there are a few improved floor screeds that have come with much better characteristics, when compared to the traditional ones. Now-a-days, even these screeds are utilised while constructing the floor.

There are mainly three types of improved floor screeds, which are as follows:

  • Fast-drying Floor Screed:

The most common type of fast-drying screeds is Isocretes, K-screed and Tarmacs Truscreed.  These screeds use super-plasticisers that help in reducing the amount of water that is required to make the screed mixture pliable.

This makes the screed to dry faster as the ratio of cement in the mixture is higher than the ratio of water.

It takes around 3mm per day for the screed to dry itself.

  • Fast-setting Floor Screed:

Fast-setting screeds like Ardex Ardurapid, Isocretes, etc. rely on the aluminium based cement as it helps in accelerating the setting process.

The time taken by these screeds to dry is a minimum of 2 days.

This system is extremely expensive and the screed quality can be very poor in comparison to the usual screeds. The major reason behind this is that, the floor layer takes less time in mixing because of its fast-setting characteristic.

  • Polymer Floor Screed:

This floor screed is usually mixed with PVA or SBR, which is added in large amounts so as to create a gluey screed.

When the screed is set, it develops a resistance power towards water and other types of chemicals. These screeds are way thinner than other non-polymer screeds.

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