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

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
         

Things to consider

• What is the condition of the substrate?
• Are there any waterproofing issues?
• Are there any cracks or voids that need filling?
• If painted, what condition is the paintwork in? Is it flaking?
• What colour do you have in mind?
• What is the approximate size of the area to be painted – how smooth or rough is the surface?
• Will you be undertaking the painting yourself?

Notes:

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

• 50-75mm Resene Blue or Resene Professional brush for cutting in
• Resene Brushable Crack Filler
• Resene Moss & Mould Killer
• Selleys Masonry Filler or Resene Epox-O-Bond

Add-ons – to make the job easier or quicker

• 35-50mm broad knife (for filling)
• Dropsheet
• Rubber gloves and eye protection

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