Floor screeds are a vital component in many construction projects, providing a smooth and level surface for the final floor covering. However, one issue that can arise is a hollow sound when the screed is tapped.
This phenomenon, known as hollow sounding screeds, can indicate potential problems that may compromise the longevity and performance of the floor. In this blog, we will explore what causes hollow sounding screeds, why they’re a concern, and how to address the issue effectively.
What Causes Hollow Sounding Screeds?
Hollow sounding screeds occur when there is a lack of proper bonding between the screed and the substrate or when voids are present beneath the screed. Common causes include:
- Poor Preparation of the Substrate: Insufficient cleaning, failure to remove dust, or inadequate priming can prevent the screed from adhering correctly.
- Incorrect Screed Application: Using the wrong mix proportions, overwatering the screed, or improper compaction during installation can create weak areas.
- Thermal or Moisture Movement: Expansion and contraction due to temperature changes or moisture can lead to delamination.
- Settlement Issues: Movement in the underlying substrate can cause the screed to lose contact.
- Air Pockets: Trapped air during the screeding process can result in voids that contribute to the hollow sound.
Why Hollow Sounding Screeds are a Problem
While a hollow sound may not always mean structural failure, it is often a warning sign of potential issues, including:
- Reduced Load-Bearing Capacity: Delaminated screeds are weaker and may crack or crumble under heavy loads.
- Moisture Ingress: Voids can allow water to penetrate, leading to damage and weakening of the screed over time.
- Floor Covering Failures: Tiles, carpets, or other coverings may become loose or damaged if the screed underneath is unstable.
- Costly Repairs: Left unchecked, hollow sounding screeds can lead to extensive and expensive remedial work.
How to Identify Hollow Sounding Screeds
Hollow screeds are typically identified by tapping the surface and listening for a distinctive hollow sound. This can be done using:
A Hammer or Mallet: Lightly tapping the screed surface can reveal voids or delaminated areas.
Acoustic Testing Equipment: More advanced tools can provide detailed diagnostics of the screed’s condition.
Marking the hollow areas during testing ensures accurate identification for future remedial work.
.
Steps to Address Hollow Sounding Screeds
Once hollow screeds have been identified, several solutions can be implemented:
Resin Injection:
- Suitable for minor hollow areas.
- Specialised resins are injected into the voids to bond the screed back to the substrate.
Overlaying with a New Screed:
- For larger affected areas, a new layer of screed may be applied over the existing one.
- Ensure proper bonding agents are used.
Full Removal and Replacement:
- In severe cases where the screed has widespread damage, it may need to be removed and replaced entirely.
- Proper substrate preparation is crucial before reinstallation.
Preventative Measures:
- Address the root cause, such as moisture issues or substrate movement, to prevent future problems.
Preventing Hollow Sounding Screeds
Prevention is always better than cure. To avoid hollow sounding screeds:
Prepare the Substrate Properly: Clean and prime the substrate before screeding.
Use the Right Screed Mix: Follow manufacturer guidelines for proportions and avoid overwatering.
Ensure Adequate Compaction: Compact the screed thoroughly during application.
Allow Sufficient Curing Time: Avoid stressing the screed until it has cured fully.
Monitor Environmental Conditions: Control temperature and humidity during installation and curing.
Take a look at our most recent screeds
Follow our socials