Near the coast, salty air wears windows and doors far faster than inland. We explain corrosivity categories, the difference between anodising and powder coating, reinforcement and hardware choice for uPVC, and care tips.
The Sarıgerme shore, the bays of Göcek, the coasts of Dalaman and Fethiye… The pleasure of living by the sea is undeniable, but salty sea air is harsh on buildings, especially on components containing metal. Salt particles carried by the wind stick to surfaces and, combined with moisture, accelerate corrosion. A window that stays trouble-free for years inland may show stains, blistering or stiffening hardware within a few seasons on the coast. In this article we explain how aluminium and uPVC frames behave in salty environments and how to choose the right material.
Corrosivity categories: know your environment
The environment that metal surfaces are exposed to is defined by corrosivity categories in ISO 9223. C1 denotes very low-corrosivity indoor environments, while C2 and C3 cover rural and urban environments. C4 refers to high-corrosivity environments such as industrial areas and areas close to the coast. C5 describes very high-corrosivity environments, for example the coastal strip directly exposed to sea spray. Buildings within a few hundred metres of the sea, especially on facades facing a prevailing sea wind, generally fall into C4 or C5 conditions.
Frames, hardware and fixings should be selected according to this category. A surface treatment adequate for inland areas may fail early on the coast. Remember that even within the same building there can be a marked difference between the sea-facing facade and the rear facade, which is why facade orientation is also assessed during the survey.
Aluminium: surface treatment is everything
Aluminium naturally forms a thin oxide layer that protects it to some extent. In salty environments, however, white stains and pitting corrosion can form on unprotected aluminium surfaces. Surface treatment is therefore critical:
- Anodising (anodic oxidation): A controlled, thick oxide layer is formed on the aluminium surface electrochemically. Because the coating is part of the material, it does not peel. A thicker anodic layer should be preferred in coastal areas.
- Electrostatic powder coating: Powder paint is sprayed onto the profiles and cured in an oven. It offers a wide range of colours. Its durability depends largely on the pretreatment before painting (chromating or chrome-free conversion coating). A pretreatment suitable for marine environments and sufficient coating thickness should be used.
On coated surfaces, cut edges, holes and screw points are the weakest spots where corrosion begins. Touching up profiles whose coating is scratched during installation is important.
The galvanic corrosion trap
Galvanic corrosion can occur when aluminium is in direct contact with a different metal and salty moisture is present. For example, fitting ordinary steel screws to an aluminium profile can quickly cause both rust on the screw and erosion of the profile. In coastal applications, stainless steel fixings should be used and insulating washers or spacers placed between dissimilar metals.
uPVC: the profile is durable, watch the inside and the hardware
uPVC profiles are unaffected by salt and do not corrode, which makes them a very suitable material for coastal buildings. However, a uPVC window is not only the profile:
- Galvanised reinforcement: The steel reinforcement inside the profile must be galvanised. Uncoated reinforcement can rust over time in windows with poor drainage, and rust stains may show on the outside.
- Hardware: Metal parts such as hinges, stays, locks and handles should be chosen with a surface treatment resistant to salty environments. Some manufacturers offer special corrosion-resistant hardware for coastal areas.
- UV resistance: Intense coastal sun requires the uPVC profile to have a formulation suitable for outdoor climate conditions. TS EN 12608 defines climate classes for uPVC profiles; the appropriate class for hot climates should be chosen.
| Feature | Aluminium | uPVC |
|---|---|---|
| Profile corrosion | Depends on surface treatment | None |
| Critical point | Anodising / coating quality, fixings | Galvanised reinforcement, hardware |
| Thermal insulation | Requires a thermal break | Naturally good |
| Appearance | Slim profiles, large glass | Wider profiles |
| Maintenance (on the coast) | Regular fresh-water rinsing | Hardware lubrication, surface cleaning |
Coastal care: fresh water is your best friend
The most effective maintenance in salty environments is surprisingly simple: rinsing surfaces regularly with fresh water. Surfaces sheltered under eaves that do not get rain hold salt longer and should be cleaned more often. Use a pH-neutral detergent and a soft sponge; abrasive products damage paint and anodised surfaces.
- On the coast, rinse frames with fresh water at least two to four times a year.
- Check and lubricate hardware at the start and end of the season.
- Clear sand and salt from the tracks of sliding systems.
- Have paint damage or scratches touched up without delay.
- Make sure the drainage holes are open.
Conclusion
By the sea, both aluminium and uPVC frames can serve trouble-free for many years; the key is choosing materials and surface treatments suited to the corrosivity category of the environment. For aluminium, thick anodising or powder coating with a marine-grade pretreatment and stainless fixings are decisive; for uPVC, galvanised reinforcement and durable hardware. Regular fresh-water rinsing extends the life of both materials. To determine the right system for your coastal building, our team offers a free site survey and measurement.
