Identifying and Fixing Common Screed Issues
A successful flooring installation needs perfectly level screed, free from cracking. It’s inevitable, though, that once in a while your screed flooring isn’t going to be up to the mark. And if that’s the case, you’re in the right place. This blog offers practical advice to help with troubleshooting floor screeding problems. Our aim is to get you back on track.
Capital Screeding brings years of experience supplying and installing liquid screed across London and the South East. We’ve seen it all and worked on numerous installations with screeding challenges to overcome. We’re going to share that expertise with you.
Troubleshooting Screeding Issues
There are all kinds of problems that can result from mistakes made during a screed installation. We take a look at the most common issues, and help you to diagnose them, and then fix them.
1. Cracks in Screed
Cracks in screed are one of the most regular problems builders have to deal with. They can be caused by poor mixing of the screed, not allowing enough time for it to cure properly, or the use of a mix that doesn’t include additives for flexibility.
How to Fix It:
- Minor Cracks – Small surface cracks are not a major problem; they can be filled using a screed repair compound.
- Significant Cracks – For larger, more extensive cracks, it may be necessary to remove the damaged section of screed and re-screed.
2. Uneven Screed Surface
Uneven screed flooring will create can real problems for final floor finishes. It’s often the result from improper levelling during installation, or inconsistencies in the screed mix. This needs to be fixed before attempting to install your flooring finish
How to Fix It:
- Minor Unevenness – Small dips or bumps can sometimes be addressed with a self-levelling compound applied over the existing screed.
- Significant Unevenness – For more substantial variations in level, it may be necessary to apply a further screed layer, feathering it into the existing surface to create a smooth transition, or in severe cases, remove and re-lay the screed.
3. Screed Curling or Warping
Curling or warping, where the edges of the screed lift or distort, is usually caused by rapid drying, especially in hot or windy conditions. This rapid moisture loss creates uneven stresses in the screed, which creates distortion. Insufficient curing time or inadequate damp proofing could also be the problem.
How to Fix It:
- Minor Curling – Minor curling can sometimes be fixed by applying a suitable bonding agent and a thin layer of self-levelling compound.
- Significant Warping – If the issue is severe, it’ll need removing and replacing in the affected areas.
4. Screed Drying Very Slowly
A screed that’s taking forever to dry can seriously cause frustrating delays. Common reasons include poor ventilation, high humidity, low temperatures, or a screed mix that’s too wet. Also, the thickness of the screed will affect drying time.
How to Speed Things Up:
Improve Ventilation – Open windows and doors (weather permitting) or use mechanical ventilation to increase airflow.
Control Humidity – Dehumidifiers can help remove excess moisture from the air.
Increase Temperature – If possible, increase the ambient temperature within the space, but don’t allow the temperature to fluctuate between hot and cold.
Check the Mix – If the screed is freshly laid, there’s not much you can do about the mix itself. But for future projects, always read the manufacturer’s instructions carefully.
5. Laitance Build-Up
Laitance is that weak, dusty or milky layer that sometimes forms on the surface of screed as it dries. It’s caused by excess water in the mix rising to the surface, carrying fine cement particles with it. This layer needs to be removed before laying any floor finishes, as it can prevent proper bonding.
How to Remove It:
- Light Laitance – A thin layer of laitance is perfectly normal, and it can be cleared away using a grinding machine.
- Heavy Laitance – A thicker layer might require more aggressive methods, such as shot blasting or mechanical planing. Always ensure you follow the manufacturer’s instructions for any equipment used.
6. Screed That Doesn’t Stick
If your screed isn’t bonding properly to the subfloor, you’ve got a problem. You can check that this is the issue by knocking on the screed and listening for a hollow sound.
Poor adhesion can be caused by a dusty or contaminated subfloor, a weak or incorrect primer, or a screed mix that’s too dry or too wet. Movement in the subfloor before the screed has cured can also be a factor.
How to Fix It:
- Check the Subfloor – Ensure the subfloor is clean, dry, and free from dust, grease, or any other contaminants.
- Review Priming – Check the correct primer was used and applied according to the manufacturer’s instructions.
- Assess the Mix – If the screed is freshly laid, this is difficult to make good. For future jobs, ensure the correct water-to-cement ratio is used.
- Mechanical Keying – In some cases, creating a mechanical key on the subfloor (e.g., by lightly scratching or scoring the surface) can improve adhesion.
7. Checking Screed Compatibility with Your Flooring
If your screed isn’t thick enough, it won’t provide adequate support for certain floor finishes. This often shows up as deflection or movement in the finished floor, and can lead to cracking tiles, bouncing floors, or other problems.
This usually happens when the initial screed depth wasn’t correctly calculated for the chosen flooring. You might notice the screed flexing or feeling springy when walked upon.
How to Fix It:
- Check Manufacturer Guidelines – Always consult the flooring manufacturer’s recommendations for minimum screed thickness.
- Top-Up Screed (If Possible) – In some cases, a thin layer of compatible screed or self-levelling compound can be applied to increase the overall thickness. However, this isn’t always feasible and depends on the specific circumstances.
- Consider Alternatives – If adding more screed isn’t an option, you may need to consider alternative flooring options that are compatible with the existing screed thickness.
When in Doubt, Call Capital Screeding
Screeding can be tricky. One wrong move—incorrect mixing, inadequate curing, or a miscalculation in depth—can lead to costly repairs and hold ups. As you’ve seen, prevention is the cheapest and best way to solve problems with floor screeding.
That’s why engaging experienced professionals like Capital Screeding is often the most cost-effective and stress-free solution. We have the expertise to ensure a perfect screed every time, saving you time, money, and headaches.
Contact Capital Screeding screeders today for a quote and let us take the hassle out of your next flooring project -030 3369 3396
