A high-quality self-levelling finish always begins with careful preparation. Pumpable levelling screeds are widely used in London renovation projects to flatten uneven floors, smooth existing subfloors, and sometimes cover underfloor heating systems. However, if the base surface is not stable, clean, and properly primed, the screed may not bond correctly, which can lead to cracks or failure later.
1) Inspect and repair the subfloor
Start by examining the entire floor for signs of movement, damage, or weak areas.
- Concrete or existing screed: remove dust, laitance, and loose surface material. Mechanical preparation such as sanding or shot blasting may be required.
- Tiled floors: check for loose tiles. If a large portion is not secure, it may be safer to remove them entirely.
- Timber floors: levelling compound should never be poured directly onto timber. Secure loose boards first, then install a rigid carrier board system, often with a decoupling layer.
Fill cracks, holes, or dips with suitable repair mortar so the levelling compound is applied to a solid surface.
2) Clean thoroughly and apply primer
Levelling compounds will not bond to dust, grease, paint, or adhesive residues. Sweep, scrape, and vacuum thoroughly.
Use the correct primer:
- Absorbent surfaces such as concrete require acrylic or SBR primer.
- Non-absorbent surfaces like tiles require a grit-based bonding primer.
Allow the primer to dry fully before installation.
3) Edge strip and set levels
Install a foam edge strip around the room perimeter to allow for expansion. Mark the finished screed height using a laser level or levelling markers.
4) Mix, pour and cure
Follow the manufacturer’s mixing ratio exactly. Pour from the furthest point of the room and use a spiked roller to remove air bubbles. Maintain room temperature around 18–20°C and avoid draughts or direct sunlight. Leave the floor undisturbed for at least 24 hours.
Why choose Floor Screeding London?
With over 15 years of experience, Floor Screeding London delivers reliable preparation and professional screeding services across London.