Common Mistakes in Screed Installation and How to Avoid Them
Screed installation is a critical component of any flooring system, whether in residential builds, commercial spaces, or industrial environments. When done correctly, it provides a strong, level, and long-lasting base. But even small mistakes during the installation process can compromise performance, lead to structural issues, and result in costly rework.
In this post, we’ll explore the most common screed installation mistakes — and more importantly, how to avoid them.
1. Inadequate Site Preparation
The Mistake:
Failing to properly prepare the subfloor, insulation, or underfloor heating systems can lead to poor adhesion, uneven levels, and cracking.
How to Avoid It:
Ensure the substrate is clean, level, and dry.
Install a polythene membrane to prevent moisture ingress and displacement of insulation.
Pressure-test underfloor heating before the pour.
Use perimeter edge strips to allow for expansion.
Pro Tip: Schedule a site inspection with your screeding contractor 24–48 hours before pouring to ensure readiness.
2. Incorrect Screed Depth
The Mistake:
Pouring screed too thin can reduce structural integrity; too thick can increase drying time and risk shrinkage or cracking.
How to Avoid It:
Follow manufacturer specifications for minimum and maximum thickness — typically 30–40mm unbonded and 50–65mm for liquid screeds over UFH.
Use laser levels or datum points to mark exact depth across the area.
3. Poor Mixing or Material Handling
The Mistake:
Improper mixing, contamination, or allowing the screed to sit too long before installation can weaken the final product.
How to Avoid It:
Use ready-mixed liquid screed delivered by an approved supplier.
If mixing on-site (for traditional screeds), ensure correct ratios and mix times.
Pour the screed within its working time (usually 2–4 hours for liquid screed).
4. Rushed or Uneven Installation
The Mistake:
Inconsistent application and poor levelling can cause high spots, dips, and delamination.
How to Avoid It:
Employ experienced installers using a screed pump and tripods to maintain level.
Avoid interruptions during the pour — screed should be installed in one continuous operation.
Agitate the screed evenly to ensure full coverage and consistent compaction.
5. Neglecting Curing and Drying Times
The Mistake:
Accelerating drying (e.g. with dehumidifiers or heaters) can cause surface cracking and internal stress.
How to Avoid It:
Allow natural drying in a controlled environment. Avoid draughts or direct sunlight for the first 24–48 hours.
Follow the screed supplier’s drying schedule — typically 1mm per day up to 40mm in optimal conditions.
Only introduce underfloor heating gradually after 7–10 days, increasing by 5°C per day.
6. No Surface Testing Before Final Flooring
The Mistake:
Installing the final floor finish without confirming moisture levels or surface integrity can lead to failure of adhesives or finish materials.
How to Avoid It:
Conduct moisture tests (e.g. hygrometer or CM test) to ensure the screed is fully dry — generally below 75% RH for floor coverings.
Check for laitance (a soft surface layer) and remove it by light sanding if necessary.
Summary: Key Mistakes & Fixes
Mistake
Solution
Poor site prep
Clean, level subfloor + polythene membrane + edge strips
Wrong screed depth
Laser leveling + manufacturer guidance
Incorrect mixing
Use pre-mixed screed + respect working times
Uneven application
Skilled team + continuous pour + tripod levelling
Rushed drying
Controlled natural drying + gradual UFH commissioning
Skipping surface testing
Moisture tests + remove laitance before final flooring
Final Thoughts
Screed installation is as much about precision and planning as it is about the materials themselves. By understanding these common pitfalls — and how to sidestep them — you can save time, reduce costs, and ensure a flawless flooring base that lasts for decades.
At Surrey Flow Screed, we bring expertise, precision, and a proven track record to every project. Contact us today for a professional consultation or site visit to ensure your screed installation is done right the first time.
