When it comes to flooring projects, one of the most critical things to consider is the drying time of the screed.

If you’re working with traditional sand and cement screed, understanding the drying process is essential to ensure a smooth and long-lasting finish.

Keep reading to discover everything you need to know about screed drying times.

 

What is traditional sand and cement screed?

Before we dive into drying times, let’s briefly cover what traditional sand and cement screed is.

This type of screed is a mixture of sharp sand, cement, and water. It’s commonly used as a smooth and level surface for final floor coverings like tiles, wood, or carpet.

Traditional screed is popular across the UK due to its durability and the perfect finish it provides for both residential and commercial properties.

 

How long does screed take to dry?

The drying time of the screed depends on several factors, including the thickness of the screed, the ambient conditions, and the specific mix used.

However, a general rule of thumb for traditional sand and cement screed is that it dries at a rate of 1mm per day for the first 40mm of thickness under ideal conditions.

For thicknesses greater than 40mm, the drying time increases to around 0.5mm per day.

Example:

• For a 50mm thick screed, expect it to take around 60 days to fully dry
• A 75mm screed may take up to 110 days

These times are under optimal conditions, which include good ventilation, moderate temperatures (around 20°C), and low humidity. Cold temperatures, high humidity, or poor ventilation can significantly slow down the drying process.

When can you walk on screed?

While screed takes a long time to dry completely, it doesn’t mean you’ll have to wait months before walking on it.

Typically, you can walk on traditional sand and cement screed after 24 to 48 hours. This period allows the screed to gain sufficient strength to support light foot traffic.

However, it’s crucial to remember that the screed is still in its early curing phase at this point. Therefore, while walking on it is possible – it’s essential to avoid heavy loads, dragging furniture, or any activities that could cause damage to the surface.

 

Factors affecting screed drying time

Several factors can influence how quickly or slowly your screed dries, including:

Thickness: As mentioned earlier, the thicker the screed, the longer it takes to dry.

Ambient conditions: Higher temperatures and lower humidity levels speed up the drying process, while cooler temperatures and high humidity slow it down.

Ventilation: Proper ventilation helps moisture evaporate from the screed, speeding up drying time.

Mix ratio: The water-to-cement ratio in the screed mix affects drying time. A higher water content means a longer drying time.

Additives: Some screed mixes include additives that can accelerate the drying process.

 

How to test if screed is dry

Using a hygrometer is one of the most reliable ways to test if your screed is dry.

This device measures the relative humidity of the screed, which should be below 75% before installing any floor coverings.

Alternatively, the “plastic sheet” test involves taping a clear plastic sheet to the screed surface and leaving it for 24 hours. If condensation forms under the sheet, the screed is still drying.

 

Why is it important to wait?

Rushing to lay flooring over partially dried screed can lead to significant issues down the line, such as:

• Cracking: If moisture is still trapped within the screed, it can cause the surface to crack as it tries to escape.
• Bonding failure: Floor coverings may not adhere properly to a damp screed, leading to peeling or lifting.
• Mould and mildew: Excess moisture can create the perfect environment for mould and mildew to grow under your floor, leading to potential health issues and costly repairs.

Start your project with JCW today!

Understanding screed drying times is crucial to the success of your flooring project. While it may be tempting to speed up the process, patience is key to ensuring a durable, high-quality finish.

At JCW Screeding, we provide expert advice and professional commercial floor screeding services across the UK, ensuring your project runs smoothly from start to finish. If you have any questions about screed drying times or need professional screeding services, don’t hesitate to contact us today.

To arrange this, give us a call at 01204 387 029 or email your queries to estimating@jcwgroup.co.uk, and we’ll get back to you ASAP.