How to choose quality aluminum windows

Recommendation points

• Features and unusual properties of aluminum profiles
• What is an aluminum profile
• Technical characteristics of aluminum profiles
• Division of aluminum profile systems into “cold” and “warm”
• Features of Aluminum Window Blocks
• Aluminum window frame
• Seals
• Filling the skylight
• Fittings, opening options
• Design issues

In the article, we will consider the advantages and disadvantages of aluminum window structures, we will compare them with wooden and PVC blocks. We will focus on the physical and operational characteristics of this profile system.

Translucent aluminum structures have been used in construction for quite a long time – from half a century for sure. Initially, they were used only for completing industrial facilities, various unheated rooms. Then aluminum systems began to appear in public buildings (shops, hospitals, schools …). In the nineties, aluminum windows took their place in apartments and private houses – it was in Europe. At the turn of the century, domestic glazing manufacturers also joined the process, and the consumer received another option for solving the window issue. Nowadays aluminum systems are actively used to create windows and doors, balconies and loggias, interior partitions, winter gardens, glass facade structures. The positive dynamics of consumer demand is clearly traced, the scope of application is steadily expanding.

Profile systems made of aluminum are clearly something remarkable, if, with the widespread tightening of requirements for energy saving in the housing stock and a relatively high price, they moved to apartments and private houses. The reasons for the popularity lie in the physical, mechanical and operational characteristics of aluminum as a building material, and a qualitative leap was achieved thanks to some innovative solutions in the design of windows.

Features and unusual properties of aluminum profiles

To understand what the pros and cons of aluminum windows are, we propose to first understand the distinctive features of the profiles from which they are made, and then consider the window block as a whole..

What is an aluminum profile

In fact, complex aluminum-based alloys are used for the production of such profile systems. The addition of other elements (silicon, magnesium, manganese …) to pure metal makes the material noticeably stronger. AlMgSi alloy is most often used to create glazing frames. The AD31 brand is the Russian version of the raw material. It meets our standards, but it contains a lot of impurities, so it is not used abroad. And the European alloys that are actively used in our country are much stricterly regulated by the content of impurities, they are marked as 6063 and 6060. The aluminum window profile is obtained by hot pressing (a heated cylindrical billet is pressed through the extruder die), our production is carried out and controlled in accordance with GOST 22233-2001. Europeans maintain profile parameters according to the following standards (by the way, many domestic manufacturers of aluminum subsystems also use them):

• DIN 1748 – strength
• DIN 1725 – structure
• DIN 17615 – geometry / tolerances

The traditional cold aluminum profile for glazing (window and door) is usually a hollow product, without intermediate bulkheads – that is, there is only one air chamber. Warm frames look somewhat different, but they will be discussed below. The thickness of the walls of the aluminum window profile varies between 1.5–2 mm, but special lightweight systems have a thinner wall – 1.2–1.3 mm. The cross-section of aluminum profiles for swing structures is similar to the well-known PVC products – there are rebates that provide the sash rebate and support for filling, as well as grooves for gaskets and grooves for fittings (Euro grooves, although they are wider than PVC – 20 mm , instead of 16 mm). It is interesting that the fold for organizing the adjoining of the glass unit to the outer seal is formed by the outer profile wall curved to the glass, while in PVC frames this is a raised outer chamber.

Depending on the type of movement of the movable flaps, the configuration of the profile can differ significantly, there are two main types:

• for swing systems;
• for sliding systems (have runners, as in wardrobes).

Technical characteristics of aluminum profiles

Aluminum profiles have several distinctive features at once, in comparison with systems made of PVC or glued timber, and all of them, to one degree or another, affect the functionality and durability of aluminum windows.

High spatial rigidity.Aluminum is about 2–3 times stronger than polyvinyl chloride and 5–7 times stronger than wood. This circumstance allows developers to create lighter frames (this is facilitated by the low density of the material), the profiles of which have a lower apparent height. As a result:

• load-bearing bases are much less loaded (for example, this is important if it is necessary to glaze a balcony with a weak slab);
• with the same glazing area, the light opening of the window (translucent part) increases significantly.

Very large sections can be created from aluminum profiles and combined into complex volumetric structures: domes, winter gardens, partitions, inclined roof slopes, straight and curved facades … The dimensions of the movable sashes, which simply cannot be made from other profile systems, can be impressive. Some manufacturers offer record dimensions of 2×2.5 meters and weigh about 200 kilograms (here, of course, a lot depends on the fittings, but the profile must hold it).

The coefficient of thermal expansion of aluminum is several times less than that of PVC.The products are very stable, cracks and deformations are practically excluded. There is no negative impact on the surrounding building structures. Due to the fact that the surfaces do not stretch / shrink, do not twist – they perfectly hold topcoats (powder coating, anodizing, veneering …). It is not necessary to use reinforcing liners, which in turn also affects the weight. Although technically nothing prevents internal reinforcement with steel or an aluminum box, nevertheless, to use it, which is what designers sometimes use.

In fairness, we note that the wood expands even less, therefore, when combining these materials, the parts have a movable connection.

Aluminum is a plastic material.On the one hand, this allows the production of profiles of the most complex configurations – the extrusion method comes to the rescue (as for PVC). It is worth noting that these profiles have high-precision geometry, which is completely unattainable for timber beams. On the other hand, it becomes possible to achieve a high level of maintainability of frames, since there are not only correctors for the outer protective layers, but also compositions for sealing large damages (popularly called “aluminum resin”).

Despite the relatively low melting point, it is still a metal, therefore aluminum structures do not burn.They are able to withstand high temperatures in case of fire for a long time and allow people to leave the premises in time, stop the spread of fire and smoke. Even fireproof glazing options with a fire resistance class up to EI60 are possible (workable 60 minutes).

Aluminum profiles are extremely resistant to external influences.No problems with UV light, aggressive urban smog and industrial emissions. These profiles are less dirty and easy to maintain (you can use any detergent).

Aluminum profiles are absolutely not afraid of moisture, so they can be used for glazing even in such difficult places in this regard, such as swimming pools or various roof structures.

Environmental Safety.The advocates of “clean” materials have a lot of questions about PVC windows. Wooden products, which need complex protection with multi-component paints and varnishes, are not ideal either. Aluminum structures are considered completely harmless, in all countries they easily pass hygienic certification (here in the State Sanitary and Epidemiological Service).

High thermal conductivity.This is the most interesting, it is worth considering this feature in more detail.

Division of aluminum profile systems into “cold” and “warm”

Aluminum has a heat transfer coefficient of about 1000 times that of PVC or hardwood. Because of this, a simple aluminum profile freezes very quickly at subzero temperatures, being an ideal cold bridge. Composite structures with an insulating insert, which are called “warm”.

The name “insert” is not entirely correct, a warm aluminum profile consists of three parts: two aluminum profiles are connected by a polyamide (polythermide) element. The aluminum frame is completely divided, there are no metal points of contact, so the exact slang terms “thermal bridge”, “thermal break” are used. A polyamide thermal bridge is most often a closed profile, sometimes two independent bulkhead strips. The assembly of a complex alumopolymer window profile is carried out on rolling devices: the ridges on the polyamide part go into the grooves of the aluminum parts and the materials are soldered. So inside the frame, closed chambers are formed from the walls of aluminum and polymer elements. There are at least three of them, but sometimes the thermal bridge liner is itself divided by bulkheads, which not only form air gaps, but also serve as additional stiffeners.

Polyamide is a laminated synthetic composite containing about 25% fiberglass, products made of it are stronger than steel and effectively prevent heat transfer. How effectively the thermal break in the window structure works depends on the width of the insert, that is, at what distance the aluminum parts of the profile are separated from each other. Usually there are options from 15 to 45 mm, for most of Russia it should be at least 25 mm. If we talk about indicators of resistance to heat transfer, then warm aluminum, on average, gives out from 0.32 to 0.55 m²?° C / W. It turns out that only the best products can be used to complete residential premises, since, for example, in Europe, profiles with thermal characteristics below 0.55 m²?° С / W for glazing of such objects is prohibited. Gradually, similar requirements appear with us..

Attention! According to the characteristics of thermal conductivity, manufacturers divide aluminum profiles into classes in accordance with the provisions of GOST 22233-2001 or the European standard DIN 4108. If you are interested in markings, it is better to know exactly what the manufacturer relied on (in both cases, the classes are indicated by numbers).

To improve the insulating characteristics, the creators of warm aluminum windows use another interesting technology – they fill the profile chambers with polymer foam materials, as a rule, it is polyurethane. By reducing convective flows inside the profile, in parallel, it is possible to increase the sound insulation of the frame, but most importantly, the thermal conductivity resistance can now reach 0.75 m²?° C / W.

So, according to thermal insulation, aluminum windows are divided into:

• cold – which do not have a polymer thermal break and can only be used for unheated rooms, inside buildings (for example, partitions);
• warm – which have a thermal insulating bridge and can be used in any conditions.

Features of Aluminum Window Blocks

Aluminum window frame

The assembly process of translucent aluminum structures is standardized by GOST 21519-2003. The frames of aluminum windows are made from a standard set of profiles (according to the nomenclature, they are the same as for PVC blocks). These are frame and sash profiles, imposts, blinds, expanders, connectors, sash adapters, glazing beads. The corner joints of the frame profiles are made mechanically (PVC – welded). To do this, use internal corner and T-shaped metal connectors (“crackers”), which are pressed into the frame parts and tightened with screws / pins. The fasteners themselves are used either from stainless steel or from very high quality galvanized steel with a coating thickness of at least 12 microns. To strengthen and protect the joints, special polymer adhesive sealants are injected into the joint area. When connecting warm profiles, corner and T-shaped fasteners are installed in both the outer and inner aluminum chamber.

Seals

Like any other window, the aluminum block is equipped with seals, which provide the structure with tightness and drainage. There are several options for solving these problems, starting from the number of contours and ending with the material and shape of the sealing element. For domestic conditions, the most optimal is EPDM tape based on natural rubbers, as it is sufficiently elastic and resistant to frost. The sectional shape is not so fundamental, but an additional contour will not be superfluous (in addition to the internal and middle, the manufacturer can add an external one, if, of course, the profile is designed for this).

It should be understood that the good tightness of a new window block often becomes the reason for the suspension of fresh air entering the apartment and, as a result, deterioration of ventilation, an increase in humidity. To prevent condensation from falling out in the window area, it is necessary to think over the methods of forced ventilation in advance. Fittings with slot ventilation can be installed, a ventilation valve can be mounted on the frame.

Filling the skylight

It is possible to fill aluminum frames with single glasses, double-glazed windows, opaque sheet materials (MDF, gypsum vinyl, sandwich panels …). The most important indicator of a window is what maximum thickness can be used for a double-glazed window, or, for example, a sandwich, since the insulating characteristics of the structure depend on this. This ability of a window is primarily determined by the depth of the frame and sash profile. Traditionally, warm aluminum systems from various manufacturers, having their own depth of about 70 mm, are designed for filling with a thickness of more than 40 mm – that is, you can install a double-glazed window of any type without any problems.

Attention! Between the aluminum frame and the glass unit, polymer spacers must be placed, which exclude the possibility of contact between the profile and filling.

An interesting feature of aluminum glazing structures is the ability to install thin materials in the frame. If you do not need special heat-insulating and sound-absorbing properties of the system (cold balcony, office partition), using large glazing beads, fix both 3-mm glass and any finishing panel such as gypsum vinyl.

Fittings, opening options

It is worth starting with the fact that the aluminum window fittings can be fixed both in the Euro groove cavity and inside the profile chamber. Despite a number of similarities with wood and PVC systems, the fittings are arranged differently here. Due to the rigidity of the frame, manufacturers managed to use fewer locking elements and connect them with special rods, that is, by reducing the list of parts, to simplify and reduce the cost of the mechanism.

In general, an aluminum window can have one or more sashes, an impostor or shtulpovy vestibule. Hardware for aluminum windows allows you to implement any currently known method of opening a movable sash, but along with suspended, swing, tilt and turn-and-tilt, there are also interesting options.

For example, the “mid-swivel” opening of the fold is very remarkable, when the blade rotates around an axis that passes through its middle. This allows you to make openable even curved windows (circle, ellipse …).

Separately, we can consider sliding systems, in which the main work is performed by guide runners (up to 3 pieces) and sash frames moving parallel to the frame with hidden rollers (up to 6 pieces). Sealing here is done with a felt brush. This design effectively saves usable space, so it is perfect for cold glazing of narrow balconies and loggias.

It is possible to make swinging aluminum canvases, folding sashes. Unusual design in aluminum windows may have hinges. In addition to the traditional options, an overhead is also available, as well as a hidden installation of hinges inside a milled groove on the box. This also applies to the handles, which are also not necessarily fixed on the frames overlay – their mechanism can be cut into the sash profile.

Accessories for aluminum windows are produced by profile companies such as SAVIO, ROTO, SIEGENIA, but some Western manufacturers of complete window systems develop and produce control mechanisms themselves.

Design issues

There is an established opinion that aluminum windows are not very beautiful, and installing them in residential premises is not a good idea. First of all, the claims relate to the “angularity” of the profiles, but now many companies produce very nice products in which both the box elements and the glazing beads are rounded.

It is also always possible to choose a profile finish. Aluminum can withstand temperatures of +200 degrees without any problems, so it can be coated by powder spraying (GOST 9.410–88), in this case the entire palette of the RAL catalog is at our service. By painting, you can imitate the texture of wood, for this, first apply the main color, and then the texture pattern. Depending on the type of composition, the thickness of the paint layer ranges from 60 to 120 microns, this is a high-quality, incredibly resistant to any impact coating.

Another great way to get a beautiful and durable protective and decorative coating is electrochemical anodizing (oxidation). A thin oxide film 5–30 microns thick is created (“grown”) on the surface of the profiles. It is noteworthy that this coating “grows” into the aluminum mass as well, therefore it is distinguished by increased strength. The oxide film, until it has passed the stage of compaction, lends itself to toning. Thus, you can create: golden coating, old bronze, black, colorless.

Aluminum windows, finished with natural or synthetic veneer, look beautiful, they are visually difficult to distinguish from wooden ones. However, the apotheosis of the design idea was the combined aluminum-wood windows. Their power base is made up of aluminum profiles, which provide the window with a bearing capacity. The decorative function is assigned to the wooden plates, which are fixed to the frames from the side of the room with sliding fasteners. From the inside, such a window looks absolutely like a wooden one – it is very solid and rich, especially since expensive wood is used for decoration – oak, ash …

Interestingly, since warm aluminum consists of several separate profiles, they can be finished using different technologies in different colors. So one and the same window can organically fit into the canvas of the facade and into any interior..

Having considered all the features of aluminum translucent structures, it is clear why their market share is slowly but growing. And for what reasons, the relatively high cost of warm profile systems does not become an obstacle for this. And if we talk about cold structures, then they can be more preferable for the price than plastic and wooden counterparts..