A wooden window is warm to the touch, pleasant to look at, and gives a house a cosy and stylish character. However, it is constantly exposed to the weather: the sun dries out and fades the paint, rain finds the smallest crack, and moisture swells the wood. Sooner or later, the window will need to be repainted.
There is a simple solution – cladding the external part of the window with aluminium. It doesn't replace the wood, it just protects it. From the inside, warm, natural wood remains, while the external weather conditions are met only by aluminium.
We have been producing wooden windows and doors for over 25 years, and for most of that time, we have been exporting to the UK, Germany, Finland and other European countries. We produce to European standards. wooden windows, terraces and sliding-folding windows and doors, folding door, external doors and authentic vertical and tilt-and-turn windows – Sash, Casement and Tilt and Turn – skirting for British heritage homes. Drawing on our extensive experience, this guide expertly lays out what aluminium cladding offers, when it's worth considering, and when simple timber becomes the better choice.
Aluminum-clad wooden windows are windows with a wooden frame on the inside and an aluminum casing on the outside.
An aluminium-clad wooden window is a composite. The frame and sash are made of solid, engineered wood. The exterior surface is covered with a powder-coated aluminium profile. Inside, you see and touch natural wood. Outside, the weather only affects the aluminium.
These two materials perform different functions. Wood is a natural insulator, warm to the touch, and easy to shape into thin profiles. Aluminium is hard, dimensionally stable, does not rot, does not swell, and does not need repainting. The coating allows each material to do what it does best.
The idea is not new. Manufacturers first implemented it several decades ago, with the aim of extending the lifespan of wooden windows and putting an end to the cycle of repainting the exterior. Modern systems go a step further, featuring a special drainage system and precision seals that eliminate the old concern about moisture build-up behind the metal.
Which Fenestrum products can be finished with aluminium?
We are installing aluminium cladding on:
- Wooden windows conforming to Euro standards with 78 mm and 100 mm profiles, Tilt and Turn and Casement windows
- For terrace and sliding partition systems away HS for lift and slide systems terrace rooms
- Folding doors
- For wooden exterior doors
These are products primarily manufactured for the Lithuanian and Western European markets, as well as for UK projects where the emphasis is on a modern, low-maintenance, coloured finish.
We consciously do not clad our vertical sliding and pivot windows. These windows are intended for British heritage and conservation properties where painted timber, slim frames and period-appropriate detailing are more important than a metal exterior. Cladding would alter the proportions and character that make them suitable for Georgian, Victorian or Edwardian homes. Therefore, we leave them as authentic painted timber windows, and apply our cladding expertise to the rest of our product range.
How aluminium trim extends the service life of wood
Wooden windows wear in a predictable way. Paint or stain breaks down when exposed to UV rays. When the coating cracks, rain reaches the wood. Wet wood swells, the coating separates further, and rot can begin from the outside in. Dark colours exacerbate this problem as they absorb more UV rays and age faster.
The aluminium trim stops this cycle right at the beginning.
- UV rays never reach the outer coating, Therefore, the finish does not whiten or fade, and never needs to be renewed.
- Rain falls on aluminium, not on wood. The timber already there remains dry.
- The profile is shaped to drain water, the drainage channels direct moisture away from the frame rather than holding it against the wood.
This is what joiners call structural wood protection: the wood is protected not only by surface coating, but also by the window's construction. This is the difference between a window that just serves its purpose and a window that requires attention every few years.
This is reflected in the numbers. A well-made, properly maintained wooden window will last about 30 years. A quality aluminium-clad wooden window will typically last 40–60 years, even in damp climates, as the ageing part – the exterior cladding – is no longer exposed to the elements.
There is a second, less obvious advantage. In strong sunlight, dark stains and finishes on unfinished wood can draw the resin out of the wood to the surface. This is a natural phenomenon and not a defect, but it is visible. Aluminium cladding eliminates this risk. Therefore, we recommend a finish for any dark colour: black, brown, dark grey, dark blue, and their shades.
Handcrafted: wooden window under aluminium
Aluminium is only as good as the wood it protects. A trim profile fitted to a poor-quality frame will still be a poor-quality window. So, the work starts with the wood.
Wood selection. Fenestrum products are most commonly made from high-quality laminated pine or spruce wood. This is a reliable and widely used choice for wooden windows and doors, ensuring stability, durability, and the natural character of wood.
Laminated timber construction reduces the natural movement of wood, ensuring frames remain straight and do not warp or bow over time.
For exclusive projects, we also offer stronger and more expressive types of wood such as meranti, sapele, mahogany or other exotic woods. For structures that require exceptionally high resistance to environmental impact and a longer lifespan, we recommend sapele or Accoya.
Joinery and finishing. The frames are processed and assembled to strict quality standards. Sealing lines, water drainage channels, and hardware housings are cut precisely, as even a millimetre's inaccuracy is precisely where air and water can enter. Before assembly, each side of the wood is treated and coated, so no part of the surface remains uncoated, and for the finish, we use the Teknos coating system in any RAL colour.
Finishing system. For aluminium, we use the „BUG Holzplus“ system from a German manufacturer – a range of profiles specially designed for wooden windows and doors. The finishing frame is attached to the wood in such a way that the aluminium can expand and contract according to temperature without stressing the wood, as metal moves more than wood in heat and cold. The profiles have their own weatherstripping, drainage, and connecting pieces as a single, coordinated set.
It's slow work, most of which we do by hand. After 25 years, we have a perfect understanding of both British and European profiles. No engineering detail can be seen from the street, and that's what's most important. A good window draws attention to the building, not to itself.
Aluminium casting in coastal and open areas
The cladding is likely to be most robust where the weather conditions are harshest, with an open coastal region being the clearest example. On the English coast and on cliff tops, a window is simultaneously attacked by three forces: salt carried by the wind, rain hitting the frame directly, and strong UV radiation reflected from the water.
Salt is the worst. Airborne chloride corrodes coatings and penetrates any cavities, as well as travelling surprisingly far inland. Unpainted or painted timber in these conditions requires constant maintenance. Aluminium fares much better, as it doesn't rust, and the timber behind it stays dry.
By the sea, the two most important details are both related to water. removal, and not just with his disagreement.
- Drainage. The profile must drain freely, with clear drainage paths so that salt-laden water never accumulates in the cavity where it can build up and cause corrosion.
- Suitable specifications. In open spaces, the type of aluminium and powder coating should be selected according to the conditions, including marine-grade coatings designed and tested with salt spray tests in environments with high chloride content.
Low maintenance does not mean no maintenance at all. Washing the aluminium with fresh water a few times a year by the sea prevents salt build-up, and the hinges need a light lubrication once a year. That's all there is to it. No repainting is required.
The windows and doors in this category are classified according to European standards applicable to air permeability (EN 12207), watertightness (EN 12208), and wind resistance (EN 12211), with aluminium powder coated according to EN 12206. If you are installing in a very exposed location, please specify the conditions when requesting information, and we will recommend the most suitable type of aluminium, coating and drainage for the location, as well as provide the performance data for your configuration.
Modern appearance, all colours
Finishing touches are not just for protection. They are also the neatest way to give wooden windows a precise, modern, and coloured exterior look.
- Colour. Aluminium can be coated with a layer of powder paint in any RAL colour, with a matt, satin or gloss finish. A matt finish has a gloss level of less than 30 %, a standard finish is around 30 %, whilst a higher gloss level provides a brighter shine. The „Coatex“ finish gives the surface a fine texture.
- Different from the inside and the outside. You are not tied to one colour. Natural or painted wood on the inside, any RAL colour on the outside. The room retains the warmth of wood, and the facade acquires precisely the shade demanded by the architecture.
- Clear, even lines. Aluminium maintains a clear, smooth profile and consistent colour across the entire façade, which is difficult to achieve and maintain using painted wood alone.
For modern homes, large terraces and lift-and-slide openings, and any dark colour, this combination is hard to beat: wood comfort inside, a clean modern facade outside, and no fading.
Aluminium-clad, all-timber or uPVC: how to choose
There are no single best windows. There are best windows for your building.
- Choose all-wooden windows, ...where authenticity and heritage are paramount. For historic buildings, conservation areas or traditional design windows with casements or tilt-and-turn frames, painted timber is the right solution, and it's precisely these kinds of windows we manufacture for the British heritage market. They do need repainting every few years, that's part and parcel of the deal.
- Choose wooden windows with aluminium cladding, if you want the warmth of wood on the inside, a modern, colourful exterior, a long service life and very little maintenance. They are suitable for contemporary architecture, open and coastal locations, large glazed areas and dark colours. The trade-off is a higher initial cost.
- uPVC There is cheaper and requires little maintenance, but it cannot match the feel of wood and aluminium, thin frames or lifespan, and can fade over time.
Heritage and tradition point to wood. Modernity, open spaces, and low maintenance costs point to aluminium finishing.
Is aluminium casting worth the cost?
Aluminium-clad timber windows initially cost more than standard timber or uPVC windows. Their benefit is over the entire lifespan of the window, not just the day you buy it.
- They serve longer. Forty to sixty years, compared to around thirty years when only wood is used, means you'll be much less likely to have to pay for their replacement.
- Their upkeep costs next to nothing. The outside does not need to be repainted or re-stained. It is sufficient to wash and lubricate the hinges once a year.
- They retain value. High-quality, durable, and low-maintenance windows increase the value of real estate and its energy efficiency.
If it's a forever home, an open location, or any project where painting would be difficult or expensive in the future, the upfront investment will usually pay off. For short-term or budget-constrained work in a protected location, simple wood or uPVC might be a smarter choice. We will honestly advise which option is right for you.
Speak to the manufacturers
„Fenestrum“ has been manufacturing timber windows and doors for over 25 years and has been exporting to the UK for the majority of that time. We produce „Euro“ windows, terrace and lift-and-slide systems, folding doors, and external doors which can be finished with aluminium, as well as authentic windows with casements and tilt-and-turn frames for heritage homes.
If you are choosing windows for a modern or coastal project, or if you simply want wooden windows that will never need repainting, we will be happy to help you choose the right option. Send us your drawings, measurements, or project description. You can contact us by phone, email, or video call, and we also invite you to visit the factory by prior arrangement.
Frequently asked questions about Fenestrum Timber Windows and Doors