How to Lay Liquid Screed Properly (Step-by-Step guide)

✔ How to Lay Liquid Screed: Step-by-Step Guide

1. 1

   Prepare the Floor Base

   Start by ensuring the sub-base or slab beneath is clean, solid, and free from debris. If you’re pouring over concrete, brush and vacuum any dust or loose material. Any uneven areas should be flattened or packed before moving on. If insulation or underfloor heating is going in, this is where it starts. Avoid pouring directly over damp soil or patchy insulation — your base needs to be 100% stable.

2. 2

   Lay Damp-Proof Membrane & Perimeter Foam

   Roll out a polythene damp-proof membrane (DPM) over the prepared area. Overlap joints by at least 100mm and tape all seams. The membrane helps prevent moisture migration and acts as a slip layer beneath the screed. Next, fit perimeter expansion foam around all walls and structural elements. This flexible edging allows the screed to expand slightly as it dries and helps with soundproofing and edge protection.

3. 3

   Install Insulation Boards (If Required)

   If the project includes thermal insulation, lay PIR or EPS boards over the membrane. Boards must be tight-jointed, flat, and stable with no rocking. For underfloor heating, make sure your insulation complies with building regs (usually 50–100mm thick). You can tape joints for stability, and if installing over uneven concrete, use levelling compound or a thin dry-sand blinding layer underneath.

4. 4

   Install Underfloor Heating Pipes (If Needed)

   Clip the UFH pipework securely to the insulation using fixing clips or pipe staples. Check spacing and layout based on your heating design — usually 100–150mm between runs. Pressure test the pipes before the screed pour to ensure there are no leaks. The heating should remain off during the screed pour and only commissioned after full drying and curing is complete.

5. 5

   Set Screed Level Markers (Tripods or Pegs)

   Position tripods or screed depth markers throughout the area — typically every 2–3 metres. Use a laser or rotary level to adjust the height of each to match your desired finished floor level. These markers guide the pour and ensure a consistent depth across the space. Double-check all levels before pouring; it’s nearly impossible to correct them once the liquid goes in.

6. 6

   Pour the Liquid Screed

   The screed is delivered via pump or boom chute. Start at one corner and work across the space methodically, covering the floor evenly. Pour until the liquid just kisses the top of each tripod. Work in strips if needed, letting the screed flow naturally to avoid overworking. Liquid screed is self-levelling, but must still be guided smoothly and steadily to avoid trapped air and thickness variations.

7. 7

   Use Spiked Roller to Remove Air Bubbles

   After the pour, immediately use a spiked roller across the entire surface. This helps release air bubbles trapped in the mix and ensures proper self-levelling. Roll gently in multiple directions to blend and flatten the surface. Avoid walking on the fresh screed — use screed shoes if movement is needed, but keep traffic to an absolute minimum during this phase.

8. 8

   Let Screed Cure & Protect the Surface

   Once poured and rolled, leave the screed undisturbed. Most liquid screeds are walkable after 24–48 hours, but full drying takes longer — roughly 1mm per day depending on thickness, temperature, and humidity. Keep the area covered, shaded, and well ventilated. Avoid drafts, heaters, or direct sun. Do not install flooring or apply sealants until the screed has passed moisture tests (typically under 0.5%).