Our Technical Representatives regularly visit properties and buildings to assess the coating requirements. Most of these assessments notes structural and building defects that affects the performance of the coatings.
Please follow our Youtube channel for surface repair and common paint problem videos. The most common issues that affects the longevity of external coatings with some sound remedial repair advice are listed below.
Surface Preparation Tips
Cleaning
To clean surfaces before repairs start typically there are a couple of solutions. Mould – Apply Hydrowash Antifiungal to infected areas and allow 24 hours to react to kill off spores.
Dirt – Wash surfaces with 1:10 Sugar soap and water solution and rinse off with fresh water or wipe off residue with damp cloth.
Laitance – Wash surfaces with 1:10 Wunda Clean and water solution and rinse off with fresh water to remove any residue.
High Pressure Washing
High Pressure washing not only removes any dirt and laitance but also exposes and removes delaminating paint and surface cracks.
Surface Repair Identification
Hairline Cracks Less Than 1mm
Open all cracks and brush clean using a wire brush. Apply one coat of Dekro Masonry and Plaster Primer into all cracks and allow 8 hours drying time before over coating. Brush Dekro Fibre Reinforced into all hairline cracks to bridge cracks. Allow to dry for 8 hours.
Plaster Cracks Less Than 5mm
Open all cracks and brush clean. Apply one coat Dekro Masonry and Plaster Primer into all cracks and allow 8 hours drying time. Cracks less than 10mm deep should be filled with PAINTER’S PAL Exterior crack filler or cementitious filler in layers of not more than 4mm at a time to allow quick drying. (Drying time depends on thickness of application).
Sand to smooth finish and remove dust. Spot prime all filled areas with one coat of Dekro Masonry and Plaster Primer and allow 8 hours before over coating. Apply one coat of Dekro Fibre Reinforced over the repaired areas and allow 8 hours drying time.
Plaster Repairs
Thoroughly inspect and hammer test all plaster and remove all delaminating plaster back to sound surface. All plaster areas to be broken out are to be squared off to allow better adhesion between the new plaster and existing substrate. Apply a mortar repair slurry .The mortar is to be well compacted in layers not exceeding 30mm and is to be trowelled off to the profile of the surrounding plaster. Plaster repairs deeper than 20mm must be reinforced with mesh or reinforcing membrane. Patches may be visible, as it is not always possible to match existing surface textures.
Spalling Repairs
Thoroughly inspect and hammer test all concrete surfaces to locate and expose defective concrete which is not readily visible. Identify and inspect cracks in order to investigate the cause of cracking. Any cracks containing corroding reinforcing steel must be cut open and treated.
All concrete areas to be broken out are to have rebated perimeter of at least 10mm deep and ± 50mm either side of defected steel Thoroughly clean down all exposed steel by abrasive grinding to remove all rust and to expose clean bright steel. Apply patching mortar with corrosion prevention additives. The mortar is to be well compacted in layers not exceeding 30mm and is to be trowelled off to the profile of the surrounding concrete. For areas of overhung concrete, light weight mortar may be used. Patches may be visible, as it is not always possible to match existing surface textures.
All structural repairs should be consulted with structural engineers and all repairs to be conducted through guidelines by various concrete and mortar suppliers.