Floor Moisture Problems: What to do and What not to do!

July 2014

Moisture is one of the prime culprits responsible for screed failure and most other flooring problems. The unsightly ripples and blisters on your vinyl, damp smelling carpets and buckling hardwood floors are signs of moisture lurking under your floor cover. The most common causes are:

    1. Laying the floor covering too soon. This often happens when you are pressed for time, and decide to lay the floor finish before the screed has completed its prescribed drying time. Just that the screed looks dry does not mean the screed is ready for the final floor finish. A 75mm thick, traditional screed takes up to 110 days to be dry and ready for the final floor finish.The residual moisture from the screed will eventually try to escape, only to be trapped by the impermeable floor covering. This will soften the adhesive which binds the floor finish to the screed, weakening the bond and causing the floor covering to lift away from the surface.


    1. Not using a Damp Proof Membrane: Not using a DPM or adequate moisture proofing system can cause the moisture from the ground to rise to the surface. This problem is more common in old builds than in new constructions.


  1. Leakage of services or accidental flooding. Leaks and spillages are also a common cause for dampness and moisture related problems. Leaks or spillages can sometimes cause surface break down in sensitive floorings, causing the water to accumulate on DPMs. The water may also pass through joints between impervious floor coverings or under skirtings and door thresholds, causing the flooring to break down.

What to do?

As moisture problems occur due to a number of reasons, it is important to carry out a thorough investigation to identify the cause of the problem before deciding on the type of repair. It is best to leave this to a specialist, as the procedure would involve a professional moisture test to assess the accurate moisture content. Remember to keep all details of construction and any earlier test data (if done) handy.

If the moisture problem is due to external sources or leakage, the moisture source should be identified, rectified and all precautions taken to prevent recurrence, before starting any remedial work.

Remedial Measures

The repair options would depend on individual circumstances. But most often, the normal course of action would be to:

    • Allow the screed/substrate to dry sufficiently, and re-lay the flooring at the end of the prescribed drying period.


    • Where required, the screed is removed and replaced with a proprietary fast drying screed like FlexiDry, laid over an impervious Damp Proof Membrane. The drying time can vary from 24 hours upwards depending on the screed type used.


    • A surface DPM along with a 3mm smoothing compound is laid to keep the moisture from the floor base from seeping up to the new floor covering. Adequate mechanical preparation on the existing screed surface is necessary to remove laitance and to ensure a good bond.


  • The floor covering is installed with a moisture resistant adhesive that is compatible with the floor covering.

Preventive Measures

    • Make sure the recommendations for screed drying times and damp proofing are strictly followed before laying the floor finish on the screed


    • Carry out an accurate moisture test on the screed before installing the final floor finish. Hygrometer tests are commonly carried out to assess the moisture content in screeds/concrete bases. But as this method does not always provide accurate measurements, it is advised to go for more reliable test methods such as the Calcium Carbide test. The Calcium Carbide test, which is carried out by mixing a small sample of screed removed from the site with a calcium carbide reagent is one of the quickest and most accurate methods of moisture assessment.


  • Make sure good quality smoothing compounds and materials are used

At HomeScreed we make sure all our screed installations follow the highest standards of workmanship and quality, and our professional screed testing services ensure that all our moisture test results are carried out scientifically, providing the most accurate results. We provide full guarantee on all our installations, and you can be assured of the best possible service. To know more about how we can help you with your floor screed , please call our expert team on 0845 500 4055.