Polyester Inspection & Maintenance

INSPECTION AND MAINTENANCE OF POLYESTER COATED STEEL SHEET

In order to meet the guarantee on the external POLYESTER coated steel sheets, and extend the life of the materials, it is important that the building is inspected and maintained at least annually, including the washing of all slopes and walls. This will need to be recorded on an Inspection and Maintenance Report an example of which is shown at the back of the downloadable form.

FACTORS AFFECTING THE LIFE OF POLYESTER COATED STEEL SHEETS

  • Proximity to marine and coastal conditions i.e. exposure to salt water etc.
  • Proximity to local pollutants and emissions from industrial, traffic and oil fired plants.
  • Extreme or abnormal weather conditions.
  • Solar Radiation – the sun affects the POLYESTER coating by ultraviolet radiation and heat.
  • Colour selected i.e. light colours last longer than dark colours.
  • Position and pitch of sheeting i.e. sun affects south facing shallow pitch roof more than north facing surfaces.
  • All kinds of damage including handling and impact.
  • Defective draining of water on slope and sealing of overlaps.
  • Exposure to harmful and corrosive substances.
  • Lack of or insufficient inspection, maintenance and washing.

REQUIRED ACTIONS FOR STAGES IN THE LIFE OF POLYESTER COATING

1. New sheet erected.
2. Chalking residues appear making the POLYESTER coating lighter and thinner but still intact. Action: If presence of chalking is unacceptable wash it away.
3. The POLYESTER coating has reduced from it’s original 25µ thickness and will crumble away when scratched. If not caught in time this will continue to deteriorate the POLYESTER coat and primer. Action: Remove paint as this has deteriorated to below satisfactory levels before re-painting.

RESTORE POLYESTER COATING

Cleaning

This is an important part of maintaining long life in POLYESTER sheeting. Whilst rainfall is usually sufficient if any deposits remain or rain water cannot reach then they need to be washed away, by means of high pressure or soft brush and water, from the bottom upwards. If debris remains, including that in roof valleys and rainwater systems, e.g. litter or fallen leaves, they should be removed annually by other means.
In polluted areas, or when there are ingrained stains, then a detergent solution may be needed to clean the sheet i.e. industrial or dishwashing detergent using the recommended dosage. Difficult stains can be removed with a soft cloth dipped in white spirit. Do not use strong solutions, organic solvents or abrasive cleaning products. After a few minutes, allowing enough time for the detergent to act, this should be rinse thoroughly from the top downwards with clean water so no detergent remains.

Touch Up

Any defects on the POLYESTER coating should be repaired. If the damage is minor e.g. scratches then this should be touch up painted. First ensure the scratched area is cleaned with white spirit and dried. Only use a soft thin brush and recommended air drying touch up paint of the correct colour. This paint may discolour at a different rate to the sheeting it is important to only paint that which is necessary. If the scratch reaches the zinc layer then a second application will be required.

Repainting

The POLYESTER coating may need repainting due to discolouration, deterioration, flaking or corrosion. This must be completed in a professional manner, ideally by experienced painting contractor, using proven paint systems and following recommended instructions.
The following guidance rules should be followed;
1. Remove any loose paint, organic material or corrosion residues.
2. Rub rust down to the bare metal including a small area of adjoining original paint.
3. Clean with an alkaline degreasing agent, such as a 5% caustic soda solution with some dishwashing detergent added to it.
4. Rinse the surface with water and dry thoroughly.
5. Paint the with a zinc rich anti corrosion primer.
6. Paint the top coat once the primer has dried.
The paint must be mixed to limit colour mismatch and applied in humidity below 80% and temperatures above 5ºC but not in direct sunlight. Use a paint brush, roller or spray gun for the work.

ANNUAL INSPECTION AND MAINTENANCE

You must inspect, at least annually, the POLYESTER coated steel sheets on the building, so maintenance if required can be carried out. The guarantee shall not be valid unless this inspection, maintenance and washing is carried out and recorded. Please find below examples of the things that should be checked and the necessary action to be taken.

TO BE CHECKED REQUIRED ACTION
Condition of the paint – Signs of chalking, discolouration, or flaking, particularly where rainwater cannot keep the surface clean. Evaluate the condition and assess whether washing, cleaning, touching up paint or repainting is necessary.
Debris in the rainwater systems – Blocked systems increase the likelihood of corrosion and consequent water leakage onto the building. Remove the debris from the systems as this binds moisture and corrosive substances.
Accumulations of waste or debris on the sheet – This increases the likelihood of corrosion as the surface under the waste is kept humid particularly if the debris itself is corrosive. Remove the waste or debris so that the sheet surfaces can dry out and corrosion doesn’t set in.
Damage to the paint coat – This increases chance of corrosion so check even if the building is new. Consider whether touch up, repaint or replacing sheets is necessary.
Wrong or incorrectly fitted fasteners – These can cause leakage and corrosion. Replace fasteners and use next largest size if threads are stripped.

 

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