How to choose quality wooden windows

Recommendation points

• Construction of a modern wooden window
• How wooden windows are made
• Technical and operational features of wooden windows
• A little about prices

In the article we will tell you about the main differences between wood windows and plastic structures. Let’s designate the main characteristics of wooden windows that you need to pay attention to when choosing one or another profile system.

Window structures made of PVC profiles are profitable and unpretentious, in almost everything they are the best. But let’s face it: if wooden window blocks were just as practical, would anyone have preferred plastic? Living and warm wood is a 100% safe material, wood products are simply pleasant to look at. It is a symbol of comfort and tranquility, cleanliness, style, prestige … but a lot of things.

In Russia and other countries of the former Soviet Union, people everywhere install PVC windows, since, first of all, it is cheaper. They do not want to engage in regular maintenance of wooden window blocks and doubt their effectiveness and durability. A wooden window is considered to be something archaic. In the European Union, things are a little different. For example, in Germany (this is where PVC was created) approximately? windows in residential buildings are made of wood. The 50% threshold, which is often cited by the manufacturers of plastic windows, is the gross share of polymer structures in the country. In Scandinavia, more than 75% of all windows (including the glazing of non-residential premises) are made using wooden profile systems. This percentage is growing, but it is not small even in countries where there are no vast areas of forests. Europeans have always appreciated the natural, but they also know how to save money. Firstly, one should not forget how stringent the requirements for thermal insulation of building envelopes are. Secondly, no one will pay a big sum for a new window every 10-15 years. So, we can conclude: they learned to make wooden windows of a new generation there. Foreign countries are in the forefront, but there are already quite a few reputable Russian companies that not only assemble wooden windows from imported profiles, but also glue and profile timber from their own forest – the basis of the window block.

Construction of a modern wooden window

Forget the Soviet “carpentry” with vents and huge cracks. At the moment, a wooden window is a complex, extremely technological product, not inferior to its competitors made of metal-plastic or aluminum. Here, the same components as in PVC products are used: warm and quiet double-glazed windows, multifunctional fittings (the same manufacturers), several sealing circuits. There are nuances, but insignificant:

• there are some differences in the shape of the hinges and the way they are attached;
• the abutment of glass to wood is sealed not with elastic profiled tapes, but with silicone, so the glazing bead becomes non-removable;
• single glass is sometimes used for filling.

Sealed, functional wood window blocks are made according to one of the structural schemes, which are traditionally characterized by the way of opening and the number of sashes. It must be said that, depending on the country where they began to use this or that design, additional popular names for different configurations appeared..

So, wooden windows are:

1. Single leaf.
2. Bivalves:
   • with double leaves
   • with split doors

Single-leaf windows. This is the most common configuration of modern wooden blocks in Russia, an analogue of the well-known PVC construction. It is based on a profile of a complex cross-section with a width of 68 to 90 mm, which allows you to install a single or two-chamber double-glazed window with a width of up to 45 mm as filling the light opening. The porch of such windows has several contact contours, which are supplied with an elastic seal. As a rule, there is one sash – large, but it is also possible to connect two sashes on one impost or with a shtulp mate (one is connected to the other directly, an open opening is obtained without a bulkhead). The movement of the sash can be rotary, tilt and swing-out. The control is carried out with one handle, the system can have a large number of additional functions: slot ventilation, opening restriction, slamming protection, microlift, protection against erroneous action, etc. Such translucent wood structures are called “Euro window” or “German window”.

Wooden windows with double sashes are not a frequent visitor in our country. Such windows are imported mainly from Sweden, therefore they are called “Swedish”. Two frames work simultaneously here, which are spaced from each other at a distance of 100-200 mm. The inner frame is usually equipped with standard tilt and turn hardware, which is operated by a single handle. These sashes are load-bearing, since external driven canvases are attached to them by means of special movable elements. The glazing of the inner frame is made by a single-chamber glass unit (sometimes with gas filling or low-emission coating). Outside, a single glass is installed, which plays the role of the first barrier that protects against atmospheric influences, dust, wind, ultraviolet radiation and external cold. To prevent condensation from forming on the outer frame, its porch is not completely sealed, which creates natural ventilation of the window.

Windows with two separate sashes are often called “Finnish”. It also uses a wide frame. In this case, the inner and outer flaps are not connected with each other. They work independently, usually in swing mode with vertical or horizontal suspension. Ventilation is carried out by means of a stepped opening restriction or by means of vents and transoms. The glazing is asymmetrical – single glass on the outside, and a single-chamber double-glazed window inside. The inner flap is sealed with two full-fledged loops, for the outer one a partially sealed boot is provided (so that there is no condensation).

The comparative advantages and disadvantages of the above design solutions are obvious:

1. Scandinavian double-sash windows are perfect for cold winter regions. First, the sheet glass in combination with the package easily provides the necessary resistance to heat transfer. Second, the wide box protects the slopes well from freezing, since the distance between the street and the room in this zone is as far away.
2. The space between the frames can be used to install built-in blinds that can be controlled when the window is closed. Unlike the lamellas located inside the glass unit, there will be no problems with repair if necessary. Also, grilles are sometimes installed inside the window..
3. Improved in double Scandinavian windows will be the performance of sound insulation. This is due to the asymmetry of the glazing, in which there is sheet glass and a glass unit, and the unequal distance between all filling elements..
4. Owners of double windows will have a little more difficulty. Compared to a single-leaf euro window, you need to wash four planes instead of two.
5. The cost of a Scandinavian block is almost twice as high as that of a similar German design.

In the west, wooden windows are used, which are not quite familiar to us. For example, “English” or “American”, in which the sash goes up along the guides. The Norwegian scheme is distinguished by the external installation of a double-glazed unit (glazing bead is located on the street side). Somewhere in warm edges, sliding windows are used, created on the basis of wooden profiles.

How wooden windows are made

For the production of modern wooden windows, various types of wood are used, which determines not only the cost of the block and its appearance, but also the physical and thermal characteristics of the window system. For example, oak is stronger than pine, but its solid mass is denser and better transfers heat, which means it is colder, and wood from the tropics is too afraid of moisture. The most widespread are windows made of coniferous species, such as pine, spruce, larch, and cedar. Hardwood varieties are also in use: oak, beech, ash, variants of tropical mahogany. It is interesting that very rarely the window profile is made of solid wood (northern pine), glued laminated timber is much more stable and stronger, it is less prone to moisture absorption. This allows you to use wood with less waste, and therefore make such windows more affordable. In any case, the technology of manufacturing wooden windows is rather complicated and the whole process takes a lot of time..

The first stage is the preparation of raw materials. A calibrated board with a radial cut, which has a margin of sectional size (for the now widespread euro-windows, it is 32×90 mm), is placed in a chamber where steaming, vacuum processing, and high temperature exposure with varying intensity take place at high pressure. Then the temperature is stabilized and the moisture content in the workpieces is equalized – the optimal indicator is in the range of 8-14 percent. These actions are properly alternated under the control of the automation, the output is a board without internal voltage, which will not crack during processing.

At the next stage, non-business pieces are cut out of the boards, the defects include resin pockets, rot, knots, shells, core, visible spots, cracks, shells … After “optimization”, many blanks are cut into small boards in length.

Planks, or as they are called “plots”, are milled from the ends to obtain thorns. Then they are processed with glue and spliced ​​under pressure. After a certain time, a prefabricated lamella is obtained. Sometimes they are not assembled on a microthorn, but a smooth fugue is used – flat ends are fitted.

Prefabricated and solid lamellas lend themselves to gouging – they are calibrated by thickness (22-30 mm, more often – 25 mm).

Lamellas are glued into a bar. Adjacent lamellas are located so that the annual rings of adjacent elements diverge in different directions. Most often, three lamellas are used to obtain one eurobeam, but some manufacturers glue additional lamellas to the sidewalls of a three-layer product – this makes it possible to increase the spatial rigidity of the finished frame in several planes. Spliced ​​lamellas are installed inside the timber, and the front surfaces are made of a solid board. In inexpensive products, external lamellas are also prefabricated. A popular option when one or two lamellas of inexpensive wood, for example, pine, are placed inside, and oak is glued on the outside. It happens that the oak element is used only from the side of the room.

The glued timber is planed on four-sided machines, its cross-section is brought to a finishing one. The workpieces are cut to length, according to the dimensions of the window block.

On milling equipment with CNC, the timber is profiled, it is given a complex section. At this stage, the contours of the porches, the rebate for the installation of the filling, the grooves for the fastening of glazing beads, seals, and fittings are made..

At the ends of the timber, spikes and lugs are cut out, or trimming is performed on a mustache (connection at 45 degrees). Note that no matter what competing manufacturers claim, both options provide sufficient reliability of the corner joint..

In accordance with the working drawings, the sash and frame are glued together, usually these works are carried out automatically.

Machine grinding is performed, then manual.

In the paint shop, a pore-filling primer and antiseptic impregnation are applied to the window profiles. These operations are sometimes performed in chambers under pressure or in a vacuum..

Using a spray gun, the wood is covered with several layers of varnish. Between “approaches” the surface is sanded to remove sagging and raised fibers.

The final phase – the window is assembled: the glass unit is mounted, the fittings are fixed, the seals are installed, the sashes take their place on the box.

Technical and operational features of wooden windows

The main working differences lie in the characteristics of wood as a material for the manufacture of the frame. If we push aside the issues of aesthetics, environmental friendliness, and other emotional moments and look a little deeper, then it will turn out to put together a list of characteristics by which one can judge the possibilities of wooden windows.

Insulating propertieswooden windows have always been at their best, since dry wood contains air pores in its mass, which impede the transfer of heat and the propagation of sound waves. It is about 20-30% better in this regard than plastic. When using high-quality glazing suitable for a certain climatic zone, wooden windows easily show resistance to heat transfer at the level of 0.5-0.7 m²· ° С / W and about 32–45 decibels – for sound insulation. We remind you once again that the softer and “looser” the wood, the warmer and quieter it is.

Spatial rigiditylaminated veneer lumber is not inferior to the metal-reinforced PVC profile. The main challenge for preform manufacturers is to correctly orient the fibers. Multilayer timber perfectly withstands any bending and tensile, twisting loads. For frames and sashes made of wood, the same restrictions on the maximum dimensions apply as for plastic – it is possible to manufacture panoramic glazing sections. The permissible sash weight is determined by the fittings. Adhesive joints, both inside the lamellas and in the corners of the window frame, are not inferior in strength to solid wood. Note that if there is any local damage, then it can be easily repaired. Corner strength according to GOST 24700-99 “Wooden window blocks with double-glazed windows” must be maintained up to 40 years of conditional operation.

Resistant to temperature changes.Unlike PVC, wood has a minimum coefficient of thermal expansion, it does not increase in size when heated and does not shrink when cooled. For this reason, cracks usually do not form in the places where the frame adjoins the capital structures. Wooden profiles do not become brittle in the cold, so they will work reliably in any conditions.

Negative influence of atmospheric humidityIs a fly in the ointment. If the tree is too saturated with moisture from the air, the product leads, it can warp, crack. Water that fills the pores negates the insulating properties of the window, wet wood becomes a favorable habitat for fungi and mold. The issue is solved by using multi-stage processing of the finished frame. Profiles are impregnated with antiseptics to protect against parasites and harmful microorganisms, the primer fills the pores of the workpiece surfaces and improves the adhesion of the finishing compounds to the base. Water-based varnishes, which are applied in several layers, create a protective outer layer that is resistant to water, mechanical stress and UV light. Every 2-3 years, wooden windows should be inspected and, if necessary, damaged areas should be tinted. For prophylaxis, once a year, it is recommended to wipe the wooden window with a special polish.

Since the upper shelves of horizontal frame profiles are more susceptible to weathering, they can be protected by aluminum or plastic covers. Sometimes “bumpers” cover all the profiles on the outside. Some firms offer a Scandinavian version of wooden windows, in which the outer sashes are completely made of aluminum..

Air permeability of the wood profile.The breathing effect of wooden windows is somewhat exaggerated. Considering the use of protective paints and varnishes for wood, several sealing circuits for the porch and vulcanizing silicone for fastening the glazing beads, we can talk about almost complete sealing of the window opening. If the ventilation in the room was designed for the flow of air through the slots of the window (Soviet system), then the humidity in the room and condensation on the glazing and slopes may rise. For this reason, wooden windows in such conditions must be equipped with supply valves..

Fire hazard of wooden windows.People obsessed with fire safety believe that it is better not to use wood for construction (for windows, it is preferable to use PVC, which itself dies out, or aluminum – “metal is metal”). In fact, this is a delusion. For the enclosing structure, which is a window, it is not flammability that is important, but fire resistance. So glued laminated timber at high temperatures, even being charred, is able to maintain its shape (better than steel), and, consequently, the operability of the window, which is necessary for the timely evacuation of people. Whereas plastic and aluminum profiles, although they do not burn, but lose their bearing capacity, they quickly deform – the window sashes jam.

Plasticity of wood.Manufacturers of wooden windows can offer the consumer blocks of any shape: rectangular, round, arched, pointed, oval, curved in a plane. Wood allows you to create unique handicrafts. Using curly cutters, craftsmen decorate profiles and binding with non-standard curved and rounded edges, sometimes artistic carving is used.

A little about prices

Wooden euro windows are more expensive than their plastic counterparts, the reason for this is the complex technology and the high cost of business lumber. Standard size (1450×1800 mm) pine block with three opening sashes (heat transfer resistance approx. 0.6 m²° С / W) will cost about 25,000 rubles. You will have to pay twice as much if you use oak. The price increase will be up to 40 percent if all profiles are protected from outside with aluminum plates. If you make a non-urgent order during the season, you can save up to 20%. There is about 10-15% price difference between windows of standard sizes and custom-made windows. Imported wooden windows are about one and a half to two times more expensive than domestic ones.

The price of wooden windows is gradually decreasing, our craftsmen are actively mastering foreign processing equipment – the products are getting better quality. We hope that soon every developer will be able to afford to evaluate timber windows objectively, without taking into account the financial component of the issue..