Thermal insulation of wooden windows

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Read in our article: “home” methods of insulating old wooden windows; insulation with the replacement of seals and the installation of a heat-reflecting film; insulation of windows according to Swedish technology – we bring the characteristics closer to plastic windows.

Insulation of windows

Heat loss in a living space increases as the temperature outside the windows decreases. First, autumn with rains, then a snowy winter with cold winds – seasonal bad weather attacks people’s houses, steals heat, the production of which takes significant sums of money … Most actively the cold of the streets penetrates into our houses through window openings, through cracks in frames and through glass, not air-permeable, but very good at participating in heat transfer. You can spend money and replace old frames with modern PVC windows or insulate wooden window frames using one of the methods described in this article and even bring their characteristics to the level of modern double-glazed windows.

Do-it-yourself window insulation – ways

The simplest “home” way to reduce the heat loss of window frames is to fill all the gaps between the window sashes and the frame of wooden windows with cotton wool, foam rubber strips or paper rolled into a tube of sufficient diameter. On top of these improvised fillers, a strip of thick paper or, more modernly, masking tape is glued. It is not recommended to use ordinary, especially colored adhesive tape, since traces of glue and paint applied to its adhesive side cannot be completely removed from the surface of window frames – the view of the window in spring will not be attractive.

Insulation of an old wooden window

If there are no problems with window insulation with masking tape, one side of which is sticky, then paper strips need to be glued to some kind of adhesive composition. Here, too, everything is simple – we take a piece of ordinary laundry soap, put a paper strip on a horizontal surface (its width is chosen so that it is sufficient for gluing to the window sash and frame along the edges of the gap), put a bowl of warm water next to it. Having dipped a piece of soap in water, then you need to take it out and run it several times along the paper strip, distributing the soap layer over its entire plane, then lift it and stick it on a certain place of the window frame. The advantages of the soap “paste” are obvious – it does not need to be made up and cooked somehow, it does not stain or damage the wooden elements of the window. In the spring, paper strips are removed from the window in one motion.

Sizing the window with paper and soap

You can insulate windows with one of the silicone sealants widely available in any hardware store. True, a small tube will not be enough – you need a large tube and an application gun to remove the silicone from it. It is best to choose transparent silicone – it will be the least visible on the window frame after application and curing. Before filling each of the window gaps with silicone, they must be thoroughly cleaned of dust and dirt, otherwise the silicone will lag behind in places and small gaps will remain.

Warming an old window with a sealant

The most effective of the “home” methods and at the same time the least attractive option for insulation is the complete overlap of the glazed window opening with PVC film from the inside or outside of the room. The polyethylene film must be of sufficient thickness to tightly cover the window frame after fixing. Installation of PVC film is carried out with a furniture stapler for 8-10 mm staples, in the places where it is fixed on the wooden frame of the window, tape or thick tape should be glued so that when the staple is driven in, it does not break the film. In living rooms, the PVC film on the windows, of course, will not look, but the window openings on the loggia can be completely blocked with it.

Thermal insulation of a wooden window with a film

Insulation of windows with replacement of seals

It is advisable to carry out the work described below in warm weather, since the window will have to be partially dismantled and street air will enter the room. If it is winter and freezing temperatures outside the window, it would be better to postpone the complete insulation of the wooden window until the warm season.

A significant proportion of the heat loss of window openings falls on the areas between the window frame and the wall of the building, since in the houses of the old building, the cracks in these places were filled with anything at all – from glass wool to pieces of rags. First of all, it is required to remove the window sashes from the wooden frame. Then it is necessary to open the joints between the frame and the wall, remove the old insulation from there, moisten the inner surfaces with water from a sprayer to remove dust, then fill the joints with polyurethane foam in two steps with a three-hour break between them.

Thermal insulation of a wooden window with mounting foam

The next step is the restoration of the wooden frame and window sashes. After a careful examination of the frame for cracks in its wooden elements and their joints, it is required to clean these places with emery cloth and putty with a special putty on wood. We take on the window panes – they need to be carefully removed from the sashes by removing the old glazing bead, carefully removing the nails with which it is fixed. By the way, before removing the glass, you need to buy a new glazing bead and nails for fixing it – the wooden slats of the old glazing will most likely be damaged during dismantling. After removing the glasses from the frames, carefully clean the surfaces adjacent to the glass sheet, then apply silicone sealant to them and put the glasses in place. If the old ones have cracks and chips at the edges, they must be replaced with new ones..

Replacing glass in a wooden window

We are starting to replace the seal. To find out the width of the slots between two paired window sashes, you will need plasticine between the sashes and the window frame – knead it, then mark it with a strip obviously wider than the width of the slots, and close the window (match its sashes). After opening, traces will remain on the plasticine, by which you can calculate the size of the slots. A rubber seal is selected according to the width of the slots – no foam rubber or something like this will fit, since they will only last for one season. Window seal made of rubber, depending on the width of the slots, differs in the cross-section of the profile: K-shaped (its cross-section resembles this letter) is intended for slots with a width of 2 to 3.5 mm; The P-shaped profile will cover gaps with a width of 3 to 5 mm; D-shaped – slots with a width of 3 to 7 mm. The choice of the profile of the rubber seal is performed as follows – if the width of the gap is, say, 3 mm, then you should choose not a K-shaped profile, but a P-shaped one.

Installing a rubber seal – the first step is to remove dirt and dust from the installation site, degrease the surface. If the profile of the seal has an adhesive layer, then there is no need to rush to remove the protective strip – first attach it to the installation site without stretching, measure the length, cut the edges at a 45 ° angle and only then stick from one edge of the frame to the other. If there is no adhesive on the seal, use silicone sealant by applying it in a strip along the length of the seal. For greater confidence in the high-quality fixing of the rubber seal on the frame, along its edges, at the cut at 45 °, one staple is driven in with a furniture stapler.

Self-adhesive window seal

The space under the window sill, if installed under the window opening, should also be checked for thermal insulation. Most often, cracks are hidden under the material forming the windowsill, through which air from the street freely penetrates inside. It is necessary to remove the window sill, clean the niche under it from debris and dust, lay a layer of mineral wool or, moistened with water, apply polyurethane foam. A day after warming with polyurethane foam, it can be cut, then covered with cement mortar on top. Keep in mind that air from a heating radiator installed under the window opening must penetrate to the inner surface of the glass – there must be ventilation slots in the plane of the window sill.

A film that reflects heat will help to reduce heat loss through the glass – it is factory-coated with a ceramic or metal coating with a layer of several microns. Reflecting about 80% of the heat back into the room, the film permeable to light and externally invisible on the glass will keep the temperature inside 2 ° C higher than in a similar room with windows not equipped with such a film.

Film for window insulation

An important point with the energy-saving film is that the coating is applied only on one side of it, with which the film must be turned inside the room, otherwise it will act the other way around, i.e. reflect the solar infrared rays from the outside and release heat from the room. Heat-insulating film for windows is attached to the inner side of the glass of the outer (outer) frame or between two glasses with double-sided tape. Before installing the film, you must thoroughly wash the glass.

Swedish window insulation

Actually, this method of window insulation is called differently – groove sealing of windows – and was developed not by the Swedes, but rather by the Germans. The groove seal owes its development to plastic and aluminum double-glazed windows that compete with classic wooden windows – rubber and silicone seals can also be used in the insulation of old-style window sashes.

The process of insulating window frames using the groove sealing technology consists of two stages:

  1. A groove with a width of 3 mm and a depth of 7 mm is cut along the perimeter of the wooden frame, for which a manual router with a high cutter speed is used.
  2. The tail end of the elastic tubular seal made of synthetic rubber (EPDM) is tucked into the groove using a seaming roller.

Window insulation using Swedish technology

In addition to milling grooves and installing a seal in them, it is required to set the same distance between the window sashes and the frame (exclude friction of the sashes on the frame), set up easy opening of locks and latches. Also, silicone sealant is applied along the perimeter of the glasses, an interframe seal is glued between the paired frames, damaged and broken elements of frame fasteners are identified and replaced.

The result of the “Swedish technology” insulation will be old-type window structures, but practically not inferior in terms of noise and air tightness to modern glass units.

Window insulation using Swedish technology

The EPDM window seal, or rather its O-shaped element, is available in several diameters – from 5 to 10 mm, usually white or brown. Producers of groove gaskets on the Russian market: domestic “Bars-profile” with the same name brand, German Trelleborg (Euro-Strip brand) and Deventer (brand of the same name), Finnish OT-KUMI OY (brand of the same name). The seal of each of these manufacturers has a corresponding marking, confirming its origin – if there is no marking, then they are trying to sell you a seal of dubious origin.

Window insulation using Swedish technology

You will not be able to perform a full-fledged groove seal of the window structure on your own – it is impossible to do this without a hand mill and a special cutter. Attempts to insulate with a sealant glued or fixed in some other way will have an effect for no more than a year – the seal will come off or partially lag behind (when fastened with a furniture stapler), the cracks will be exposed and the tightness will be lost.

Important: the sealant with Swedish insulation cannot be glued – only inserted into a specially prepared groove!

Window insulation using Swedish technology

The groove seals are made from two materials – EPDM rubber and silicone. Rubber seals will last about 15 years, silicone ones less – about 10 years.

The installation of seals and the complete elimination of all existing gaps in the window structure will lead to a lack of fresh air. For this reason, it is worth installing supply and ventilation valves in airtight windows, through which fresh air in a small but sufficient volume will enter the room. The following manufacturers of ventilation valves for windows are represented on the Russian market: Russian Air-Box with the same brand name; German Trocal (AirMatic brand), Gealan (Gekko brand), Kommerling (KoClimat plus brand), Siegenia (Aeromat brand), Rehau (Climamat brand); French Aereco with the same brand name. The cost of the supply and ventilation valve will average 3,000 rubles, depending on the brand and manufacturer.

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