Concrete floors

How to deal with common problems with concrete floors: cracks, uneven floor surface, and more.

Concrete floors can act as a thermal heat storage mass. If used with insulation in the walls and ceilings, this helps to keep stored heat inside.

See www.cca.org.nz for detailed information on working with concrete.

Uneven floor surface

This can happen if the concrete is poorly laid.

Check the floor with a straight edge or spirit level to find high spots or depressions. High spots may need grinding, which is a job for the professionals. Low spots can be levelled with a floor levelling compound. Follow the manufacturer’s instructions.

Cracks in the concrete

You can repair minor cracks with concrete patching compound. For major cracks which are getting wider, seek professional advice.

See www.cca.org.nz or www.mcpa.org.nz for more information on how to install concrete and to diagnose and repair damaged concrete.

Concrete profile showing through the vinyl

This can happen if the vinyl has been laid over poorly finished concrete.
To fix the problem, remove the old vinyl. Grind the concrete smooth or level it with epoxy compound and lay new vinyl.

Bubbles appearing under vinyl

This can be due to:

• Moisture rising through the concrete.
• The wrong adhesive being used to lay the vinyl, or
• The vinyl being laid before the concrete has dried out.

If the problem is moisture, lift the vinyl and allow the concrete to dry properly. You may need to apply a damp proof epoxy coating to the concrete before laying a new floor covering. If the problem persists, seek professional help.

A new concrete floor (up to 100mm thick) should be allowed to dry for at least four months (longer in winter) before vinyl or tiles are laid. Thicker concrete will take longer to dry.