Moisture Testing for Screeded Floors : What is it and Why is it Important?

moisture testing

Liquid Screed is increasingly becoming a popular flooring option in the UK. This is due to several reasons, including fast installation times and less product usage. Also, it has little waste during the installation process.

Like most flooring options, shoddy and unprofessional installation can result in unnecessary and costly repairs. One of the essential aspects of installing liquid floor screed is moisture testing. Ideally, you have to ensure the screed is dry before installing tiles, carpet or vinyl.

In this post, we’re going to explore more on moisture testing for screed floors. Keep on reading to learn more.

What is Moisture Testing for Screed Floors?

Before laying any floor coverings or smoothing compounds, screed must meet certain installation regulations.

As such, the moisture content of your screed should be below 0.5 percent. Anything above that can cause your tiles to blow and your vinyl to bubble. Also, you can check the humidity, which should be less than 75 percent.

It takes about 60 days for screed to cure, after which you can test the moisture level. A standard 75mm screed usually takes up to four months (110 days) to dry to an acceptable level.

Even after the screed has dried, its advisable to maintain a relative humidity of 50 percent and a controlled temperature of 20C. This will ensure proper laying of the final floor finish.

It’s the responsibility of the floor finishing contractor to ensure correct moisture levels before laying the finish.

Keep in mind that it’s possible to speed up the drying process using a boiler. Be sure to work with a SafeContractor accredited contractor with OFTEC engineers if you want to use this service.

How to Test Your Screed Moisture Level

There are several methods for carrying out moisture level assessment. You can carry out a DIY test to know if your screed is dry. But, it’s usually advisable to work with a professional contractor to ensure accurate test results.

1. DIY Test

In this test, you will need a thick polythene sheet and duct tape. You will also need something heavy and flat, such as a board or plywood, to place over the sheet. It’s not a requirement, but it’s good to have it.

For this test, you will need to do more than one test. This is because some areas can be drier than other areas.

Just take the sheet and lay it down on the area where you want to test. Then use the duct tape to tape down the edges. You can then place the board or plywood over the sheet.

Leave the test in place for about 12 to 15 hours then remove the sheet. If there are wet patches on the screed, it means it hasn’t dried yet. Even if there are no wet patches, you’ll still need a professional moisture test.

2. Using Air Hygrometer Test

The British Standards Code of Practice recommends this method for moisture testing for screed floors.

This method involves sealing an area of the floor for about 72 hours. A calibrated hygrometer will be placed on the screeded floor before sealing the area. A professional will then measure the moisture released into the sealed area.

In this test, the results obtained only show the humidity in the sealed area. You may need to test another area again. The problem is that the air hygrometer test is somewhat time-consuming, so it’s not widely used these days.

Also, it’s not recommended for modified screeds, which usually form a chemical bond with water.

3. Concrete Moisture Test

Most manufacturers and contractors prefer this method because it gives speed and accurate results. Today, there are two moisture testing methods under the concrete moisture test. They include:

  • Calcium carbide test: Here, a professional allows a screed sample to react with calcium carbide reagent. This mixture releases acetylene gas during the reaction. The amount of the gas indicates the moisture level in the sample.
  • Tramex meter: This concrete moisture meter is fast and offers accurate readings. It’s basically an electronic device that is put on the screeded surface to read the moisture level. It will display the results in percentage.

After obtaining the test results, it important to consult different professionals. This will depend on the type of finish you want for your floor. If the moisture level is above the desired level, you can wait longer is the project doesn’t have a strict timeframe. Or, you can use a surface DPM to suppress the moisture vapour.

Importance of Moisture Level Assessment

As noted before, your screeded floor needs to meet certain moisture level standards before laying the finish.

The last thing you want is to apply your floor finish prematurely. Any excess moisture levels can result in a host of problems for your floor coverings. Some include condensation, adhesive degradation, movement, and delaminating.

If your screed didn’t dry well, your wood flooring could swell, cup and move. High moisture levels will also lead to the emission of harmful vapours and mould growth.

These problems can lead to the fresh installation of your floor coverings. This can certainly be costly if your initial budget didn’t accommodate such scenarios.

Moisture Testing – Final Thoughts

If you have an water underfloor heating project or you want to install floor covering, it’s important to ensure your liquid screed has dried adequately. You can either use calcium sulphate screeds or faster drying cement based screeds for your projects.

Faster-drying options can dry fully within 14 to 21 days compared to their counterparts, which can take up to 110 days. Whatever the case, it helps to carry out moisture testing to ensure the moisture level requirements are met.

At Gyvtec Ltd., we are a team of liquid screed and underfloor heating specialists to help you with your project. If you any question, feel free to reach out to us for a consultation.

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