Collage of freshly laid floor screed in two different building applications.

Do you want smoother floors in your home? Are you tired of seeing cracks as you walk through your commercial property and want to get rid of them? Or maybe you just want something to protect your new underfloor heating system. If any of these is something you desire, you could do with a layer of cement screed. This brilliant mix provides both homes and commercial buildings with smooth, level floors that offer comfort and style.

But how are these floors screeded? Well, we're here to share with you all the secrets of how screed is added to a property's floors, from preparing the mix to quality assurance. It'll help you envision the process, and help you decide whether you wish to do it yourself or use a trained professional.

Let's get started.

Key takeaways

  • Floor screed is essential for both residential and commercial properties, offering smooth, level surfaces and enhancing underfloor heating systems.
  • Preparation is crucial before installing screed, including site preparation, installation of underfloor heating (if desired), and planning the screed mix.
  • Curing and drying are vital steps after screed installation to ensure strength and durability.
  • Techniques such as moisture retention, temperature control, and ventilation are essential during the curing process.
  • Regular inspection and testing ensure quality assurance and compliance with safety standards.
  • Properly installed and cured screed floors last longer, enhance safety, and meet regulatory requirements.

Why use floor screed in my property?

Screed is an important part of many construction projects, especially when it comes to strengthening your floors. Whether it's for your home or office spaces in a commercial property, you should always consider adding a layer above your substrate before installing your final flooring. It's often a mix of cement, water, and sharp sand and can be bonded, unbonded or floating. It levels and smooths out your floors, offering comfort and preventing any issues in the future.

On top of the main purpose of screed, it's also beneficial when paired with underfloor heating systems. After you've installed your system, you should always add a layer of screed on top of the underfloor heating pipes to not only protect it, but improve the transfer of heat throughout your property.

There are various types of screed materials, such as the traditional cement screed, self-levelling screed, fibre-reinforced screed (made out of polypropylene fibres), and fast-drying screed. The type you choose, also including bonded and unbonded screed, will depend on your individual preferences and the needs of your property.

Preparing for screeding

Collage showcasing professional concrete screeding on three distinct sites.

Before you can install floor screed in your property, you need to do a bit of screed preparation first. Here are some of the ways you can get your property ready for the process:

Site preparation

The first thing you've got to do to prepare your property for liquid screed or self-levelling screed installation is to prepare the floors. This includes sweeping the subfloor to remove dust and debris and ensuring there aren't any contaminants that might get in the way. You should also check for any holes, cracks, or unevenness that need to be addressed during installation.

If you want to reduce the chance of mould or other moisture issues, we recommend adding a damp-proof membrane during this process as well.

All of these initial checks and steps will ensure you have the foundation for a seamless installation, and it reduces the chance of any issues arising in the future.

Installing underfloor heating

This step is optional, as it depends on whether you want to install an underfloor heating system in your property. If you do, then this needs to be done before you can add a screed layer, as it needs to go on top of it. Depending on the type of system you want to install, you'll either have to connect the cable system or lay the floor heating pipes before proceeding.

As the screed will also secure the underfloor heating system in place, you also want to check to ensure it's running smoothly first. The best thing to do in this case is to use a trained professional, so you don't experience any problems in the future. You'll then have a good-running system and a screed layer that you never have to worry about.

Planning the screed mix

It's now time to get your screed mix ready for installation. Depending on the type you want to use, this process will be different, for example, if you want to apply cement screed on your concrete floor, then you need to put together the mix of sand, water, and cement in the right ratios.

You can either purchase your screed mix from a supplier and create it yourself, or you can work with a professional who brings the screed ready to use with them. This all depends on whether you're doing the installation yourself or how much you want to spend.

The screeding process

If you follow our preparation tips correctly, you'll be all ready to screed your floor. Here is a step guide to ensure you get the job done to perfection:

  1. Divide up your entire floor area: Divide your floor up into sections. You can use dividers such as long pieces of timber without any dents or unevenness. It's best to wet them before applying so you can easily remove them afterwards.
  2. Add your screed: Add your screed mix on top of your underfloor heating system, insulation boards or damp-proof membrane. Spread it out evenly from the section farthest from the room's entrance with a trowel, and compact it with a screed board. It is most recommended to use a professional for this stage.
  3. Level your floors: If you're not using a self-levelling screed, you'll need to level it yourself. You can do this using a straightedge by placing it over your dividers and pushing it forward. Continue to move it in a side-to-side sawing motion to move the screed layer.
  4. Repeat the process: You will now have completed the first section of your floor. You now need to move to the next section and repeat the process in steps 1-3. Once you've done every section, you can remove the dividers and fill the gaps.
  5. Float your screed: If you spot any imperfections in your screeded floors, you must remove them before it starts to dry. Float the area until the whole room is level and it looks completely smooth in every section.
  6. Cure your screed: The final step here is to cure your screed floors. We will go more into this in the next section.

Curing and drying

Optimal floor screed in a large house room from two different angles.

Once you've finished our step guide on how to install the screed, you are ready for the final stage of the process, which is curing and drying. Here is all the information you need to know about the two to ensure the best floor finish:

Importance of curing

Curing is a step you can't miss when you install screed in your property. This is because it allows your applied mixture to become as strong and durable as possible. Before you cure the screed, there are a range of chemical reactions that take place in the mixture which causes the surface to harden. However, this can sometimes cause cracks and shrinking, which also makes the screen look bad.

By curing your floors, you prevent these issues as you stop the screed from drying too quickly. On top of this, it ensures that there is a suitable amount of moisture throughout the screed, which promotes consistent drying. Giving yourself enough time for this step ensures your screed will stay with you for years to come without the need for repairs or replacements.

Best techniques

Since curing is such a crucial step, you want to ensure you're doing it right. Here are some of the best techniques you can use to guarantee optimal results:

Moisture retention

The best thing to do when curing screed is to ensure the layer is kept moist. You can do this by covering it with damp hessian, plastic sheeting, or a specialised curing compound. It ensures your screed doesn't get dry too quickly and remains hydrated.

Temperature control

You need to regulate the temperature in the room where you've applied the screed. By maintaining an ideal temperature of around 10 to 25 degrees, you will experience the best results. If it's too cold or too hot, it can negatively affect the curing process.

Ventilation

Not only do you need to look out for the temperature, but you also need to ensure your screed has access to proper ventilation when it's curing. This prevents too much moisture from building up under your chosen cover, which might lead to mould in the future.

Duration

How long you cure your screed is important. You need to ensure you leave enough time so your screed builds up its strength. It's recommended to allow for your screed to cure for at least a week under all the conditions we've mentioned above, but it can vary depending on your screed mix and the surface area, so contact a professional to find out the best time for your situation.

Regular inspection

Keep an eye on your screed throughout the curing process to see if any problems are arising. Things you should look out for, in particular, include signs of drying and cracking. If this seems to be happening, simply reapply moisture or adjust the conditions.

Factors influencing drying time

As we mentioned, the amount of time you leave your floors to cure depends on various factors. Here are some you should consider:

  • The type of screed mix you're using, such as sharp sand and cement screed, self-levelling screed, or screed made from polypropylene fibres. There are also fast-drying screeds that have much faster drying times.
  • How thick you apply your screed will affect how long it takes to dry. The thicker it is, the longer it will take.
  • The conditions you're curing your screed in will affect its drying time. For example, the temperature, humidity levels, and ventilation. However, ensure you aren't trying to speed up the process too much by changing the conditions, as it can cause cracking.
  • The moisture content of the subfloor beneath your screed can influence drying time. Higher moisture levels can delay the drying of the screed.

Testing and quality assurance

Once your screed is cured and dried, it's always a good idea to perform some final checks to ensure its strength and durability.

How to test screed strength

If you want to ensure your screed is strong and ready to be covered with the flooring of your choice, you can do something known as the scratch test. You can use a sharp object, like a screwdriver or screed board, and scratch the dry surface gently. If it remains intact and doesn't crumble, then it's strong and ready to go.

Another method you may want to use includes a rebound hammer. This measures the screed's hardness by extracting a sample and sending it to a lab for testing. However, this is a lot more extensive and could end up costing more, so the scratch test might be your best option.

Importance of quality assurance

So, why should you check for the strength and hardness of your screed and ensure it has been properly installed and cured? Here are a few of the main reasons:

  • Stronger screed floors last longer as they are more durable. They can withstand heavy loads without fear of breaking or cracking, meaning you won't need repairs.
  • Quality assurance of your screed isn't only good for durability, but it's also good for your safety. By looking for uneven surfaces, it prevents the risk of any injuries.
  • By looking for any early issues, you can fix them then and there. This saves you on costly repairs in the future when the issues start to get worse.
  • When living in a property, you often have to meet regulations in a housing association. Quality assurance ensures the screed meets the required performance and safety criteria.

Conclusion

Screed is an extremely beneficial addition to all floors, and no property should go without it during construction. From providing smooth and level floors to protecting and enhancing underfloor heating systems, it comes with a wide range of benefits. However, having the mixture installed properly is essential, so you can make the most of these advantages.

For a helping hand and guaranteed quality in installation, Next Level are here to help. We serve properties around Scotland by installing innovative underfloor heating and applying strong screed to floors in homes and commercial properties. Contact us to find out more or for a free consultation.

Collage displaying completed screed work in various areas of the house, perfectly smooth and leveled.

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