What to think about when choosing your floor screed

Mislaying floor screed is one of the most common causes of delays in commercial flooring projects.

Because the screed sits directly under the final layer of flooring, it has to be done right before anything can progress.

From choosing the right type of screed, to mixing it properly to get the right finish, to laying it correctly so it settles level and stands up to strain once foot traffic increases there’s lots to think about, and lots that can go wrong.

Just imagine the time and money you’ll waste if you come to lay the flooring and it doesn’t fit together.

Or the surface underneath is uneven with lots of bumps.

Or there’s too much moisture running below.

This will all ruin the final outcome and could lead to you having to re-screed the floor.

Here are a few questions when choosing floor screed. 

What’s the building going to be used for?

What the building will be used for impacts your choice of screed massively.

The building’s final purpose – whether it’s domestic or commercial – will determine the thickness of screed you’ll need.

For a heavily used commercial area with lots of foot traffic and heavy machinery you’ll need a high strength screed.

In domestic buildings, which typically have lighter foot traffic and furniture, a quicker drying screed can be a better option.

Because of how fast it dries, you can get flooring like carpet down a lot quicker and don’t have to worry about denting or cracking the screed in the process.

How quick do you need it to dry?

There are a few varieties of floor screeding and they all dry at different speeds.

It can take some type of screed months to fully dry, so you need to factor this in when planning your projects.

These are a few types of screed you can consider for various situations:

• Fibre reinforced sand and cement screed – a screed solution that includes polypropylene fibres to minimise shrinkage and cracking
• High strength screed – good for areas that will have a lot of foot traffic and need to hold large pieces of equipment or machinery
• Fast drying screed – great for domestic areas if you need to get flooring down quickly

Before you pick your screed, you need to know what type of flooring will be going on top of it.

If you’re planning on putting tile or vinyl down for example, the screed needs to be completely dry before you start putting the floor down.

If you install the floor too early, it could absorb the extra moisture and create unwanted bacteria.

What kind of foot traffic will you have during the installation?

Screed can take a few days to dry out enough to sustain light foot traffic, so if you’re going to have a lot of people walking around you’ll need to consider that.

Will the screed be put down in a commercial building?

If the building will have heavy foot traffic and equipment being delivered during the installation, you’ll need to consider the drying time of the screed and when you want it to be finished.

You want to make sure any equipment or machinery is installed when the screed is completely dry, to limit heavy foot traffic and any damage to the surface.

If the floor screeding isn’t fully dry and you try to install your machinery, the screed could dent or crack under the pressure.

This will lead to an uneven surface when any flooring is put down.

By understanding how long your chosen floor screed takes to fully dry, you can make a plan for when other equipment and flooring can be delivered without affecting the screed itself.

Are you going to use underfloor heating?

If you are, it might change the type of screed you can use.

You can use floor screeding if you’re having underfloor heating fitted, it helps secure the pipes and create a smooth surface on top of them.

Before you do this, you need to know that the average thickness of the screed is around 25-40mm.

Will this be enough to cover your underfloor heating?

Before choosing a screed, make sure you know the depth of the underfloor heating so you’ll know how much you’ll need to cover it.

If you don’t use the right amount of screed to cover the eating pipes, it can lead to an uneven surface and prevent them from working properly.

Are you putting the membrane down first?

Waterproof membrane can be put down to stop ground water soaking into the floor.

This will change the type of screed you can use because you’ll have to determine the depth you can go.

Screed can be installed under or over a membrane.

Which you do depends on how much water the area will be exposed to, and what flooring you’re putting on top.

For example, tile adhesive is not compatible with membrane, so if you’re having tiles fitted, you’ll install screed on top of membrane.

Drying times should also be considered when combining screed and membrane.

This ensures the floor screed is dry and you have an appropriate surface to put the membrane on.

If you’re installing screed underneath the membrane and didn’t give it enough time to dry, the membrane won’t do its job properly.

This will lead to bacteria and unwanted moisture in the flooring.

Are you putting floor insulation down?

Floor insulation can also affect the type of screed you’ll need.

This is because of the depth of both the floor insulation and the screed combined.

The combination of the two acts as a great insulator to prevent heat loss, but it needs to be done properly to have the desired effect.

Screed is used over insulation boards to make sure they’re firmly in place and keep the heat in.

Although screed is typically used alongside insulation materials, it also acts as a very effective insulator on it’s own.

When combined with insulating materials like perlite and pumice, screed can prevent heat loss as well as providing an even surface.

When it comes to saving time and money, using just one material for insulation like screed is a good alternative.

Deciding on the right screed flooring for you

Overall, there are lots of questions you should be asking before you decide on the right screed for you.

With so many varieties, it’s important to do your research before taking the plunge.

If you don’t get it right the first time, you could spend thousands of pounds to correct or re-do the process.

If it’s a commercial area like a college, it could majorly disrupt the project and delay the finished result.

If you’re having underfloor heating, insulation or membrane down along with screed, you need to make sure you plan in advance to get the best outcome possible.