Preparing Your Site for Liquid Screed Installation: A Step-by-Step Guide
Preparing Your Site for Liquid Screed Installation: A Step-by-Step Guide
Liquid screed has become the go-to solution for efficient, high-performance flooring, especially when paired with underfloor heating. But a successful screed installation doesn’t start with pouring — it starts with proper preparation. In this guide, we’ll walk you through the essential steps you need to take to ensure your site is ready for a smooth and flawless screeding process.
Why Preparation Matters
Correct preparation is critical. Poor prep work can lead to issues such as cracking, uneven levels, or compromised drying times. Following industry best practices can help you avoid costly delays and guarantee long-term performance.
Step 1: Ensure the Area Is Weatherproof and Watertight
Before any screeding begins, the building or project area must be enclosed, weatherproof, and at a stable ambient temperature (ideally between 5°C and 30°C).
Seal windows, doors, and roofing to prevent wind, rain, or excess moisture from interfering.
Avoid drafts that could cause uneven drying or surface skinning.
Step 2: Prepare the Substrate
The sub-base beneath the screed plays a crucial role in structural integrity and even drying.
Clean the substrate thoroughly — remove all debris, dust, and contaminants.
Ensure it's flat and compacted, with no voids that could lead to cracking.
Install a suitable damp-proof membrane (DPM) to protect the screed from rising moisture, especially for ground floors.
Step 3: Install Perimeter Edging Strips
Perimeter edging strips allow for the natural expansion and contraction of the screed during drying and temperature fluctuations.
Fix these strips to all walls, columns, and fixed structures.
Ensure a consistent height — they should extend slightly above the finished screed level.
Step 4: Lay Insulation and Underfloor Heating (If Applicable)
If using liquid screed with underfloor heating, now is the time to install:
Rigid insulation boards laid flat and taped at joints to prevent floatation.
UFH pipework should be pressure-tested and clipped securely, with manifolds installed in an accessible location.
Reinforce high-traffic or load-bearing zones with mesh or appropriate structural layers.
Step 5: Install a Polythene Slip Membrane
To prevent the screed from penetrating or displacing the insulation and pipework, a polythene membrane is laid:
Use 500-gauge (or higher) polythene sheeting.
Overlap joints by at least 100mm and tape them to form a continuous seal.
Ensure no creases or holes are present.
Step 6: Confirm Levels and Set Datum Points
Accurate leveling is vital for screed performance and flooring finishes.
Use a laser level to set a clear datum point (benchmark for screed height).
Mark the screed level on walls and ensure the liquid screed will be poured to a consistent depth — typically 50mm–65mm for underfloor heating systems.
Step 7: Final Checks Before Pouring
Restrict site access to prevent contamination or damage to the prep work.
Confirm site readiness with your screed contractor, including access routes for pump equipment and delivery.
Ventilate appropriately, but avoid forced drying during the curing period.
Summary Checklist
✔ Weatherproof and secure the site
✔ Clean and level the substrate
✔ Apply a DPM if required
✔ Install perimeter edging strips
✔ Lay insulation and UFH (if applicable)
✔ Position polythene membrane
✔ Set screed levels and datum points
✔ Restrict site access and confirm contractor readiness
Final Thoughts
Taking the time to properly prepare your site for liquid screed installation is the foundation of a successful flooring system. Whether you’re working on a new build, a retrofit, or a commercial fit-out, these steps will ensure your screed performs to the highest standard — delivering a flat, level, and durable surface ready for final finishes.
If you’d like expert guidance or a site survey, contact Surrey Flow Screed for professional advice and a no-obligation consultation.
