Can you paint a metal or tile roof, and should you?

Roof coating is legitimate work that has acquired a poor reputation, mostly because it is the product most often sold door to door and most often applied to roofs that needed replacing.

Metal roofs

• Coating a sound but faded metal roof is reasonable and can extend its life, particularly with a coating that reflects heat.
• Surface rust must be treated before coating, not covered.
• Perforated or heavily corroded sheeting cannot be saved by paint, and coating it wastes the coating.
• Preparation matters more than the product: pressure cleaning, treating corrosion, and an appropriate primer for the substrate.

Tile roofs

• Concrete tiles lose their surface coating over decades and become porous, and recoating genuinely helps.
• Terracotta tiles are glazed and generally should not be painted at all.
• Broken tiles must be replaced and ridge capping repointed first, or the coating simply covers the defects.
• Coating does not restore a tile that has begun to delaminate.

The heat argument

A light coloured or specifically heat-reflective roof coating reduces the temperature of the roof space, which reduces summer cooling load. On an uninsulated or poorly insulated home the effect is noticeable. On a well-insulated ceiling it is much smaller, so it is worth insulating first if you are choosing between them.