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Painting cementitious surfaces cracked and/or leaking - painted or unpainted


Resene Popular Paint Systems –
Concrete, plasters and cement-based substrates: training notes

This web page is an edited version of the Resene Best System Selling training notes provided to Resene staff and is provided to enable you to gain a greater understanding of the substrates and paint systems you may encounter in your decorating project. It is impossible to cover all decorating scenarios in a single document, so if you are in doubt about any aspect of your project please contact Resene for assistance.

How to paint cementitious surfaces cracked and/or leaking - painted or unpainted


(Preparation)

Note: Refer to the PDF flowchart for a visual of the steps below:

  1. Apply Resene Moss & Mould Killer

  2. Is the substrate, including any existing paint in sound condition?

    1. If No:
      1. Waterblast to remove flaking paint
      2. Spot prime bare concrete areas using Resene Sureseal
    2. If Yes:
      1. Wash using Resene Paint Prep and Housewash
  3. Fill cracks and voids:

    1. Cracks under 1mm, use Resene Brushable Crack Filler
    2. Cracks over 1mm, use Selleys No More Gaps exterior formulation or similar
    3. Holes and voids, use either Resene Jointflex or an approved masonry filler
  4. Is waterproofing an issue?

    1. If No:
      1. Refer to topcoat systems flowcharts
    2. If Yes:
      1. Apply 2-3 coats of Resene X-200

Cementitious surfaces that are cracked and / or leaking - painted or unpainted

Things to consider

Notes:

Cracked flakey paint
  1. Some very old buildings may originally have been coated in a limewash or similar, very poorly bound paint. Typically they are very weak and friable and while waterblasting will remove the layers of paint, it may be a mammoth and unwanted undertaking.

    The alternative is to thoroughly scrub and wash to remove the worst flaking areas, spot prime with Resene Sureseal and paint with Resene AquaShield, Resene X-200 or Resene Lumbersider.

  2. If there is a black paint beneath the coating, this is most likely to be bitumen based and you should refer to the next flowchart.

  3. We have combined unpainted with previously coated as there is no difference in terms of surface preparation except that instead of spot priming with Resene Sureseal a full coat may need to be applied.

Key accessories essential to complete the job

Add-ons – to make the job easier or quicker

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