STEP-BY-STEP GUIDE

How to fill outdoor wall cracks

How to fill outdoor wall cracks

You will need:

  • Render mix
  • Trowel
  • Exterior stabilising solution
  • Sponge
  • Wire brush
  • Coal chisel
  • Sandpaper
  • Water
  • Old paint brush

Outdoor walls always take a beating from the wind, rain and changes in temperature. A few cracks and paint flakes shouldn't get you in a tizz. They can be filled and filed away so you can get your wall looking as good as new. Eventually a badly cracked wall will need to be replaced, as it will get increasingly unstable. But this quick fix can buy you a couple of years before you need to say bye-bye to your old wall.

Time to complete the job: 20 mins plus drying time

  • Step 1: Make a bigger crack

    Step 1: Make a bigger crack

    OK, it might seem counterintuitive to make the cracks bigger, but it's easier to fill a bigger crack. Use the coal chisel to scrape the crack until it is bigger, deeper and wider. Blow any dust away from the crack.
    Use the paint brush dipped in water to pick up any last dust in the crack.

  • Step 2: Fill the crack

    Step 2: Fill the crack

    Use the trowel to work some render firmly into the crack. Smooth the render with the back of the trowel until it is even with the surrounding wall.

    Wait about half an hour until the render is almost dry to the touch.
    Rub the rendered area with the sponge, which will make the edges of the render smooth with the wall.

    Tip: Use render that is nine parts soft sand, two parts lime and one part cement. The lime will give the cement some pliability, allowing it to expand and contract.

  • Step 3: Cure paint flakes

    Step 3: Cure paint flakes

    Use sandpaper to rub away any flaky bits of paint (this is called feathering in).

    Put a blob of render in the flaked area and smooth it with the trowel.
    Once the render is almost dry to the touch, smooth it with the sponge.

  • Step 4: Prepare to paint

    Step 4: Prepare to paint

    Before painting the wall, use the wire brush to clean and scrape away any dirt, moss or debris. Then coat the wall with exterior stabilising solution. When the solution dries, paint the wall with exterior paint.