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The Process of Laying Self Levelling Screed

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When you lay ceramic tiles, vinyl carpet, and other floor coverings. Self-levelling screed level out uneven substrates, leaving a flat, smooth surface to join to.

Before laying self-levelling London, its suitability has to be established. The majority of projects will comprise three kinds of substrates that are as follows:

Construction Types

Bonded is a crucial aspect of the self-levelling screed laid since it relies on the bond that is formed with the substrate. Self-levelling screed is appropriate for this kind of construction.

Unbonded is when you have a membrane between the screed and the substrate. This kind of screed is not one that would work with this kind of screed.

Floating construction is when the screed is placed on insulation, whether it’s thermal or acoustic insulation. This kind of construction is not one which is suitable for this kind of screed because the bonding process is typically required.

Sound Substrate

When it comes to bonding, I think it is essential to draw attention to the process. If we are looking on the surface, it has to be solid. When we talk about “sound,” it needs to be a solid. If there is cracks, crumbling, or other issues, you must take action prior to placing the screed. There’s no reason to installing self-levelling screed over something that’s not stable as it could result in the screed breaking or separating.


The screed should be checked to make sure that the substrate has not been affected. Contamination could be caused by a range of things like dust, grease, oils and anything else that could have entered the crevices in the screed (the capillaries of the screed). If there’s contamination, it might require a mechanical surface preparation. This could include grinding/scabbling or blasting. If there are any traces of paint on the substrate, it should be removed prior to laying self-levelling screed.

The surface should be cleaned and vacuumed if there is dirt or dust in the substrate. Prior to laying the self-levelling screed,, a primer should be placed on the substrate in order to aid in the fusion of the self-levelling screed to the substrate. Sometimes, it is possible to lay without primer. Always check the instruction before you lay. In any case, you’re going to require some penetration of the surface. It must bond to the matrix, which means that you have to grind away the initial couple of millimetres of the matrix in order to grind it down to something that can bond.

When the concrete substrate has made of power floated concrete and the top layer of the matrix has be removed to be able to access the more open texture of the concrete, which will allow the primer to get into. Certain products could be placed directly on the surface that is power floated However, again you must take a look at the specifications for each specific product. In general, you’d be considering changing the mechanical properties of the surface in order to facilitate more adhesion between screeds and substrate.

Self-levelling Screed Thickness

When laying self-levelling screeds, the thickness will vary from one product to the next but as a guideline, look at the following depths:

The minimum depth is typically 2-3mm There are products that be lowered to “featheredge”

Maximum depths are about 10-15mm but when you add bulking aggregates (normally dry sand that has been kiln dried) when you lay self-levelling screed, it can be as deep as a of 30mm.

Substrate Moisture

Generally speaking, when you lay self-levelling screed, the surface should be at 75 percent of relative humidity. in the case of a membrane that is liquid damp proof may be required to reduce the moisture available.

I would suggest that the surface be examined for moisture prior to any work.

Primer/Bonding Agent

If you are completely satisfied by the surface, you’re prepared to put on the primer, which aids in the bonding between the screed and the substrate.

Every product will come with an approved primer that has been tested and may come with different ratios to water. Always confirm the manufacturer’s guidelines before using.

The primer generally needs to be dry prior to the laying of self-levelling screed. However, it shouldn’t be allowed to sit for more than a few hours (always be sure to check the product’s directions).

For applying the primer, make use of a brush and make sure there’s no poolsing in the prime.

Screed Mixing

When mixing by hand with an electric drill it is added in the right volume of water (again follow the manufacturer’s specifications for their products) while mixing well until a smooth mortar is formed.

This screed then laid on the substrate and laid out to self-level. screed. It is then spread using a trowel made from steel or floating floats to make the mortar spread and to finish.

In general, the screed will self-smooth within about 15 minutes. It will last for a total period approximately 30 minutes dependent on the temperature of the site.

Drying Times

The conditions on the site will affect drying times, but 3 millimetres of screed will typically dry in 24 hours and walkable within 3-4 hours.