Aluminium Windows and Doors for Coastal locations

What special considerations need to be taken into account for aluminium doors and windows in coastal locations?

Any property on a coastal, exposed, or high-level setting is subjected to the extremes of the British weather.  These areas tend to be wetter, windier and much harsher than towns and cities. Not only does the exterior of the property get a battering, but so do the windows and doors.

In this article, we provide some tips, advice and a bit of insider knowledge in what you should know about windows, doors or bifolding doors for coastal, severe or exposed environments.

Some basic information about polyester powder coated windows and doors.

If your home is on a coastal or other 'severe' location your windows and doors may need a paint warranty.
If your home is in a coastal or other ‘severe’ location, your windows and doors may need a paint warranty.

Polyester powder coating is the most common method of colouring and protecting aluminium. The companies specialising in the powder coating of aluminium extrusions are approved, accredited and inspected by professional organisations that monitor and quality control this particular sector.

All these expert finishing companies pre-treat and paint their windows to British and European standards and work very closely with the global businesses that manufacture the polyester powder itself. The major manufacturers of polyester powder are Valspar, Syntha Pulvin, Axalta, Interpon, IGP and Tiger.

In general terms, a powder coated aluminium window or door has been expertly painted by very experienced companies that specialise in colouring and protecting aluminium and steel for construction, not just windows and doors.

In very broad terms your standard powder coated aluminium door or window will come with the following paint guarantee:

  • Matt finishes 25 years
  • Gloss finishes 10-15 years.

These guarantees are on the paint finish only and not on the overall window, its operation or the installation. They may vary depending on the colour of the window, the make of the powder used to coat it, the applicator and other factors. That said, these guarantees are perfectly acceptable in the door and window industry and have been in place for over three decades.

Where windows are likely to be fitted in more severe environments, a more specific paint application may be required and consequently a longer paint guarantee. This is because paint finishes can suffer as a result of being ‘exposed’. While a powder coated window is protected as standard there may be situations where the normal finish is not acceptable and may fail over time because of where it is located.

What is a severe environment for windows and doors?

Powder manufacturers set guidelines as to what constitutes a severe environment. Examples are city centres, industrial sites, swimming pool environments and coastal locations. As one example Akzo Nobel say:

A marine environment is any location within 5,000 metres of a coastal shoreline and may also include areas such as estuaries and tidal rivers. A Coastal environment is determined as one that is within 5KM from any coast or estuary.

An industrial environment is any location within 5,000 meters of a source of solid, liquid or gaseous airborne pollution that may cause the degrading of the powder coating.

All powder coatings are required to meet industry standards.  These are currently BS EN 12206-1:2004.  Powder coating firms may also be Qualicoat Approved. This standard asks for the paint film thickness to be no less than 40 microns and on average no less than 50 microns.

Where windows are to be fitted in marine or industrial environments, guidelines generally state that aluminium components should have a minimum film thickness of 70 microns on all significant surfaces.

Every manufacturer of polyester powder sets out different criteria for the quality of the paint finish in these situations. Syntha Pulvin is another global company making powders. They state that aluminium should be coated to 60 Microns, that only Matt or Metallic matt finishes are used, joints are sealed with an approved mastic and there should be no exposed metal edges. This logically leads to another issue with windows for marine, coastal or swimming pool environments – how they are made.

Do windows in coastal locations need to be made differently.

The short answer is yes for a very simple reason.  Aluminium is powder coated in bar lengths.  It is painted first and then it is cut to the required size for making the windows and the doors.  It is therefore logical that when a saw cuts the painted aluminium bar, it not only leaves exposed edges but a badly maintained saw and blade can also chip the paint itself. In most cases this might be invisible to the naked eye but it does happen. When the two corners of the window are put together there is a risk that pollutants can get under the paint finish and corrode the paint and the aluminium.

The proper sealing of window joints is a prerequisite with virtually all modern aluminium windows. Where windows are to be fitted in exposed locations it may be necessary to ensure that window joints are sealed with an approved mastic or small gap sealant. Failure to do this can result in the paint finish getting damaged and causing damage to the aluminium window as well.

So as you can see, there are many factors involved in ensuring that the paint finish on aluminium windows is protected and to help ensure a good lifespan for the windows. This is because aluminium powder coated windows are affected simply by being outside. Abrasion, Salt, Pollutants and Contaminants can all affect the paint finish.

Architects and the wider construction industry have known about special paint guarantees for many years already and factor this into their building design and how they specify the construction material overall. For the grass roots installer and the consumer what does this mean in practical terms?

How do you know if your windows and doors need a marine guarantee?

The process for obtaining a paint guarantee for coastal windows and doors is actually quite simple.  Each powder coater uses a simple form that asks for specific information about where the doors are located and other quite simple questions.  You can see a sample form that the door and window industry uses to request a marine warranty. A window installer will obtain this form from their supplier that obtains it from whoever paints and supplies their aluminium.

In very broad terms a door with a marine warranty has a thicker coating of paint, sealed window joints and will be required to be cleaned more often. Generally speaking, marine and coastal areas are those within 5km of an estuary or the saltwater location. If you doors are between 1/2km and 2km from the coast a more detailed cleaning method will be required. For windows and doors that 1/2km or less from the coast at best you’ll get a reduced warranty. At worst you will be refused one.

  • The decision to provide a marine warranty rests with the powder coater and nobody else. It’s their decision whether to provide one.
  • There is no certainty that a marine paint guarantee it will be provided just because of the coastal location. These warranties have to be applied for on an individual basis.
  • If a warranty is to be issued it will come with conditions such as cleaning schedules.
  • Some RAL, Syntha Pulvin or BS colours cannot be given with a warranty.

By far the most important requirement to ensure your guarantee is honoured is routine cleaning.  The window industry loves to market windows and doors as ‘maintenance free’, the reality is some routine cleaning and maintenance is required.  For powder coated finishes with either a standard or marine guarantee, the expectation from the powder coaters is that the finish will be routinely cleaned.  For marine guarantees the cleaning schedule is more regular.  Often that is all that’s required to honour it. For commercial buildings especially the powder coaters will want to see evidence of routine cleaning having been carried out.

What else should you know about windows and doors in exposed locations?

  • Our recommendation is to seek clarity on whether you need a marine warranty before you place any order for your windows and doors.
  • Doors in sheltered locations or under canopies may be more protected from the weather but they’ll also be less exposed to rainfall washing contaminants away as well.
  • Consider the quality and finish of handles and hinges in exposed locations.
  • If your supplier or installer seems reluctant to provide a warranty be suspicious. There should be no reason this can’t be investigated and obtained.

Published on July 22, 2016

Reader Interactions


  1. Helen Elliott says

    Hi Nick,
    We live on the Solway Firth and get the brunt of the Irish Sea, the wind and rain batter the house. Our Upvc double glazing is not marine grade and will need replacing in the future. What is the best double glazing on the market for our area and the conditions please

    • Nick Dardalis says

      Hello Helen, Schuco, Reynaers, Comar, Aluk are all good windows with excellent weather ratings. This article is about the paint finish in exposed locations rather than the windows themselves.

      If you’d like to get in touch via our contact form I’ll try put you in touch with some local installers.

  2. David Kerrigan says

    Looking to replace a 4.5m triple track sliding all direction doors and other contemporary style windows.
    As we live 200m from the sea in a front line property is there a manufacturer that uses anodised and marine grade powder coating on their products for such locations, or will they all do it as an extra? What is the price premium for this spec or are there products that already come with that spec?

    • Nick Dardalis says

      Hello David, it’s hard to tell you who uses pre-anodising and a marine grade with a warranty powder coating. If you’d like to get in touch via the contact form with your location I can try to assist with an installer near you.

      Hope this helps
      Kind regards,

  3. Luyanda says

    Hi i am considering changing aluminium window and door frames to timber frames please do advise me on the merits of this change. I am not to far from the coast

  4. Elaine George says

    I am renovating a sea fronted property in the Caribbean.

    North East facing. Covered by a canopy and around 60 feet from the actual coast. There is no direct sunlight hitting the doors after 11am.

    I am looking for the longest lasting and best covers.

    What is the best aluminum / paint covers for this kind of bi folding sliding door?

    Best weather bearing hinges….brass? aluminum?

    I was looking for doors to be supplied in the UK and shipped to the Caribbean.

    • Nick Dardalis says

      Hello Elaine, not sure on this one as I can’t imagine the costs of transportation and ensuring a smooth installation would be cost-effective? However, worth getting in touch with the below systems companies as they do have international operations and see if they can help you.

      I’m not too sure in specifically in your area, however, if you get in touch with the below systems companies they should be able to help you.

      These three well-known systems all offer steel look windows and hopefully they can put you in touch with a local installer.


      Sorry I can’t point you in the direction of a specific one at this time.
      Kind regards

  5. Nick Dardalis says

    Hello Tahir, thanks for your question. The Anodising process is a different process to a powder coating and its an alternative way of protecting aluminium. It has a lot of benefits over powder coating and is more durable in many cases as it penetrates deeper in the profile whereas powder paint covers the bare surface. The two are not the same in appearance or how they’re applied to the surface of the aluminium profile.

    To the best of my knowledge, any project where the windows are known to be in a coastal location should get the powder coating or anodising applicator if you want a specific guarantee for the finished aluminium in that location.

    Talk to your chosen supplier or get in touch with your location and will try to help.

  6. Tahir Ali says

    Hello Nick,

    For a coastal location is anodized aluminium advisable? I am unclear as to how anodizing relates to the polyester powder coating. Is it done prior to the powder coat or instead of the powder coat? I would be grateful if you could clarify this.

    Thank you

  7. Suresh Shah says

    Hi, are uPVC windows more coastal friendly than powder coated aluminum? The residence is 25 meters from the ocean with nothing in-between.

    • Nick Dardalis says

      Hello Suresh, it really does depend on the individual product and what guarantee your supplier is quoting for this. Plenty of PVCu windows are fitted in coastal locations.

      My advice is this. If you get a very straightforward ‘Yes’ with little further explanation from the companies you speak to, go up a level and speak to the Technical Department at the systems company. It is very easy for a salesman to just rely on the 10-year guarantee and leave it at that. If your windows are that close you need the peace of mind by seeing any certification/documentation as to the suitability of the windows for coastal locations. So speak to the Systems Company behind any PVCu window as well.

      Hope this helps
      Kind regards

  8. Lesley trivett says

    We would like to know what frequency of cleaning are you saying in a coastal environment. We have a bay window 20 feet from the sea so get spray and wash on the windows.
    We are wanting to change the window .

    • Nick Dardalis says

      Hello Lesley, the frequency of cleaning is usually set by the powder coating company depending upon the level of guarantee offered with the paint finish. However if you are that close to the sea I think at least monthly cleaning would be required if not more often.
      Kind regards