Find the cause of corrosion
Corrosion occurs when steel, moisture and oxygen come together. Salts, industrial pollution, damaged coatings and permanently wet details can speed up the process.
On metal roofs, cut edges, overlaps, fasteners and gutters are often affected before the flat sheet material. Condensation on the inside can also play a role.
Inspect existing coatings
Determine where the old coating is still attached, where sub-rust is present and whether several unknown layers have been placed on top of each other. A new layer depends on everything that remains underneath it.
Test adhesion and a test surface can help. If there is any doubt about compatibility, an existing layer will not be worked over without technical approval.
Preparation is not an afterthought
Loose rust, poorly adhering coating, grease, dust and salts must be removed to the prescribed initial condition. The required preparation varies per system and corrosion load.
After preparation, bare steel can quickly re-oxidize. Cleaning, checking and primer application must therefore be planned in a controlled time window.
- Degrease and clean
- Assess salt load
- Remove loose corrosion and coating
- Treat edges and fastenings separately
- Register preparation level
Details require extra attention
Overlaps move and trap dirt or water. Fasteners can leak and cut edges have little existing layer thickness. These zones often require a targeted primer, sealant or elastic detail treatment.
Gutters and drains are assessed for water level, deformation and accessibility. An elastic coating does not replace missing fastenings or steel plates that have become too thin.
Build up protection in a controllable manner
Primer, intermediate layer, detail material and final layer must demonstrably match each other. Environment, UV exposure and desired maintenance period also determine the structure.
Register consumption, dry layer thickness where relevant, batch data and photos. Periodic inspection focuses on damage, edges and overlaps.
This explanation is general and does not constitute project-specific system advice. Subsurface investigation, tax and official system documentation remain decisive.