Screed Curling or Lifting at the Edges – Causes & How to Fix It

Contact

Why Is Your Screed Lifting at the Edges?

If your screed is curling, lifting or rising up at the edges, it usually means the material is drying unevenly. This is more common with unbonded or floating screeds, where the top dries faster than the bottom, causing the edges to contract and lift away from the slab or insulation.

Curling doesn’t always mean failure, but it can cause issues with floor coverings, visible gaps, and in worst cases, cracking or delamination. This guide explains why screed curls at the edges, what type of screed is most at risk, and how to stop it happening — or fix it if it already has.

Common Causes of Screed Curling or Lifting

  • ✔ Uneven Drying

    The top of the screed cures faster than the bottom, causing tension that pulls the edges upward — especially in warm or draughty rooms.
  • ✔ Poor Edge Restraint

    If perimeter foam or edge joints aren’t installed properly, the screed has room to curl or lift instead of staying supported at the edges.
  • ✔ Inadequate Curing

    No curing compound, polythene sheet, or spray membrane means moisture escapes too quickly, increasing the risk of surface shrinkage and curling.
  • ✔ Screed Too Thin at the Edges

    If the screed thins out near walls or corners, there’s less mass to hold it down — making it much more likely to lift or crack.
  • ✔ Floating Screeds Over Insulation

    These are particularly vulnerable if not compacted and levelled properly, as there’s no bond to the substrate to hold the screed flat during curing.

Self-Levelling Screed

  • Flows and settles with minimal manual levelling
  • Can reduce surface tension if poured evenly
  • Often has built-in shrinkage control additives

Self-Levelling Screed

  • Still vulnerable to curling if curing is rushed
  • Thin edges and gaps more likely to lift
  • Requires precise temperature and humidity control

Traditional Sand & Cement Screed

  • Thicker and heavier — less prone to lifting if compacted well
  • Dries slower, which can reduce curling if cured right
  • Better edge hold when bonded directly to concrete

Traditional Sand & Cement Screed

  • More manual effort to level and compact evenly
  • Still curls if top dries faster than the bottom
  • Requires control joints to reduce stress build-up

✔ How to Prevent or Fix Screed Curling at the Edges

  1. 1

    Control the Curing Environment

    Use plastic sheeting, curing compounds, or temporary coverings to slow moisture loss and ensure even drying across the slab. Avoid exposing fresh screed to direct heat, sunlight, or strong draughts — especially during the first 48–72 hours.

  2. 2

    Maintain Consistent Screed Thickness

    Screed that’s too thin near edges or corners is more likely to curl. Always follow recommended minimum depths, especially when floating over insulation (e.g. 65–75mm for sand/cement, 50mm+ for liquid screed).

  3. 3

    Fix With Re-Bonding or Feather Repair

    If curling has already occurred, edge lifting can sometimes be fixed by grinding down high spots and re-bonding with flexible repair mortar or epoxy filler. In extreme cases, you may need to cut out and re-lay affected sections.

🔹 Is screed curling normal?
Slight curling, especially around the perimeter of large floating screeds, is fairly common — but it should be minimal and not affect floor covering installation. Major curling usually means something went wrong with curing or prep.
🔹 Can I tile or lay flooring over a curled screed?
Not without correction. Curling can cause uneven spots or hollow sounds under tiles or vinyl. You’ll need to grind, fill or re-bond the affected areas before laying anything on top.
🔹 Is it worse with floating screeds?
Yes — floating screeds laid over insulation or DPMs are not bonded to the slab, so they’re more vulnerable to curling or edge movement if not cured and installed correctly.

Free Quote for Concrete Flooring in the UK

Our team of experts is ready to transform your floors with precision and craftsmanship. Don't settle for ordinary when you can have exceptional. Contact us now for concrete floors in England and Wales by emailing us at info@britishconcretepolishing.co.uk or by filling in the form below and our team will get back to you shortly.