Installation of Plastic Windows | uPVC Windows

Installation of Plastic Windows | uPVC Windows

The installation of plastic windows is a serious undertaking that is best entrusted to experienced craftsmen. If during the installation all the nuances are not taken into account, then during the operation of the windows, problems may arise, including: poor tightness, heat leaks, as well as fogging of the glass unit. This article will consider the design features of polymer windows, as well as the algorithm for their installation in multi-storey buildings and private wooden houses.

Plastic window construction

There are three main elements:

  • frame;
  • double-glazed window;
  • accessories.

The frame is the load-bearing part of the structure. Inside there is a strong profile – the base, which can be plastic or metal (in the latter case, the window is called reinforced). The space around the profile is divided into sections (chambers). There can be two of them (two-chamber profile), 3, 4, maximum 7. The more, the different and warmer the uPVC product.

Double – glazed window – consists of 2, 3 or more glasses. The space between 2 glasses is called a chamber (there can be at least 2 of them). The air in the cells does not allow noise and cold to pass through. The chambers can be filled with inert gas – it copes better with heat conservation and noise.

The insulating glass unit is held inside the profile by means of a glazing bead – a flexible plastic strip.

Fittings are a set of locking mechanisms, handles and other elements necessary for locking and unlocking the doors.

The movable part of the window block is called a sash . It can be swivel or swing-out. In the places where the flaps are connected, seals are laid – rubber, rubber or silicone tapes necessary for tight closing.

The blind (non-opening) part can be divided into sections by imposts – vertical plastic uprights.

The window structure stands on a support profile – a uPVC support that separates the bottom frame and the wall part. Prevents the formation of “cold bridges”. Reduces the risk of condensation.

Additional elements

Slopes – decorative strips on the sides and top, covering the wall around the plastic box. They are made of plaster or removable materials – drywall, plastic panels.

Window sill – a ledge at the bottom of the window.

Low tide – “window sill” from the side of the street. Protects the assembly seam from moisture, rain.

Step-by-step installation of plastic windows

Consists of the following steps:

  • measurements;
  • dismantling of old elements;
  • surface preparation;
  • installation;
  • installation of ebb tides;
  • installation of a window sill;
  • final stage and quality control.


Measurement rules:

  • The space is measured from the inside and from the outside, in height, width, diagonal.
  • Width and length are measured in several places, as wall surfaces are not perfectly flat. The minimum value is taken as the final one.
  • If the opening on the outside is smaller than on the side of the room, then it is “with a quarter”. This is the name of the protrusion of the wall from the side of the street, which keeps the glass unit from falling out. The name came about because of the width of 6.5 cm, equal to ¼ of a brick. For such houses, different measurement rules apply.

Measurements are taken from the outside. We take into account the layer of plaster: we find out its thickness using a narrow screwdriver probe.

We get the width of the box: the distance between the walls outside (A) – 20 mm each on the sides (20 mm – the gap for the assembly seam)

We get the height: the distance between the point of abutment of the low tide to the profile and the upper border of the opening (H) – 25 mm

Dismantling old windows

Protect furniture and surfaces from dirt.


  • a hammer;
  • hacksaw;
  • adjustable wrench;
  • scrap;
  • screwdriver;
  • putty knife;
  • screwdrivers;
  • grinder.

Dismantling the wooden frame (without saving the product):

  • remove the sash;
  • take out the window sill (use a hacksaw or grinder);
  • cut out the frame racks;
  • unscrew or remove the fasteners with a nailer, remove the window frame.

Dismantling the uPVC system:

  • remove the sash;
  • remove the glazing beads from the blind parts and remove the glass;
  • remove the window sill: to remove the concrete slab, use a hammer and grinder, for wood, marble, plastic – a chisel and a hammer. Work carefully, do not damage the bottom edge;
  • remove the ebb;
  • remove the frame structure: it is more convenient to use a cutter, but you can work with a hacksaw or jigsaw;
  • remove the slopes (from drywall, plastic), if they are cemented, skip this step;
  • remove the insulation;
  • clean the remains of mixtures, other materials with a spatula and / or a brush.

Surface preparation

All work consists in leveling and priming the wall surfaces.


The opening should be as “rectangular” as possible, without potholes and protrusions not to exceed vertical and horizontal deviations of more than 4 mm per 1 meter. And the irregularities should not be deeper (higher) than 1 cm.


The wall part is cleaned of glue and cement residues, dents, potholes and other defects are repaired.

Surfaces are primed with primers. In the last step, we recommend applying a primer with a waterproofing effect. This will prevent water from entering the installation seam.

The inner and sides of the quarter require preparation. Irregularities are sealed with cement mortar or special mixtures. Ready-made compounds are strong, harden in a few minutes.


There are two mounting technologies:

  • with preliminary removal of the double-glazed window;
  • without removing the glass unit.

The technology for installing plastic windows with the extraction of a double-glazed window is chosen when the installation of overall windows with an area of ​​4 sq. m.

The essence of the technology is that the frame is drilled through and its internal bearing profile is attached to the wall. Anchors and pins are used as fasteners.

  1. Pick up the hardware.

Fasteners are selected taking into account the wall material, their strength:

Fastener name When to use
Anchor dowels – metal spacers For houses and buildings: concrete, expanded clay concrete, aerated concrete, natural stone, brick (vertical voids are allowed)
Frame dowels – plastic For building structures with an increased aggressive environment, when the risk of corrosion of internal elements is especially high
Plastic dowels (with locking screw) For brick houses (including those with vertical voids), lightweight concrete, timber, hollow blocks and other materials with minimal compressive strength
Iron screw-dowel for concrete Self-tapping screw with uneven threads for working on concrete substrates. Provides a secure fit without loosening
  1. Remove the sashes and take out the glass unit.

Use ordinary pliers to remove the sash and glass unit:

  • remove the decorative plugs from the canopy;
  • open the sash;
  • squeeze out the stem (metal rod inside the hinge) from above and below;
  • mark the glazing beads so as not to be confused when returning to the place;
  • remove the vertical glazing beads (use a “boot knife”);
  • remove the horizontal glazing beads (carefully pull out of the grooves);
  • remove the glass unit from the frame.
  1. Lock the frame, align it horizontally / vertically.

Use mounting wedges and pads. The structure will be based on them during the installation process. Slopes, if any, can be compensated by using support blocks made of plastic or wood. Acceptable deviations of the wall opening from the vertical / horizontal – no more than 4 mm per 1 meter, frame deviations – no more than 1.5 per 1 meter.

  1. Attach the window block:

  • on the inner surface of the frame, mark the installation locations of the fasteners;
  • mark and on the surfaces to which the box will be attached;
  • select a drill for an electric drill according to the diameter of the anchor bolt;
  • make holes in the profile according to the markings;
  • take a punch or drill, make holes in the walls. Set the rock drill to no impact mode if it is not a concrete surface.

The recommended distance between adjacent anchors is 60-70 cm.

We insert an anchor into a concrete wall to a depth of 40 mm, into a stone (made of natural stone) – from 50 mm, from lightweight concrete – from 60 mm.

Start attaching from the bottom of the structure. Insert the anchor, but do not tighten it, but first check the vertical / horizontal position of the product. Do the same for the middle and top of the frame. After making sure that the box is level, tighten the anchors until they stop. If there is a deviation in the process, remove the fasteners and align the window frame again.

Put plugs on the places of the fasteners, if the fasteners “went into the frame”. Remove mounting wedges if used. Assemble the block in reverse order: insert the glass unit, install the glazing beads, knock with a rubber mallet (mallet) so that the glazing beads are firmly pressed against the glass. Please note that black rubber can leave marks on white plastic.

  1. Place the assembly seam.

The assembly seam has three layers:

  1. outer vapor-permeable;
  2. central – polyurethane foam with a heat-insulating effect;
  3. internal vapor barrier – tape or mastic.

Such a structure does not allow moisture and vapors to penetrate from the room into the seam and does not allow cold and moisture to pass from the street into the room. The seam is ventilated from the street side: all moisture accumulated in it goes outside, and not inside the room.

Avoid creases. Do not apply plaster or other compounds to the tape.

Apply foam:

  • choose the foam taking into account the temperature outside: see the instructions for use on aerosols;
  • before applying the material, moisten the surfaces or walk with a primer (the rule does not apply if it is minus outside);
  • apply foam in a continuous line, do not leave voids, breaks;
  • do not cut off excess foam from the outside;
  • cut off the excess inside if the vapor barrier is to be laid;
  • if the gap between the frame and the walls is very large, apply the foam in layers, each time waiting for the previous layer to cure.

From the side of the room, glue the vapor barrier tape over the resulting seam, remembering to overlap in the corners.

  1. Install the ebb. 

This must be done immediately in order to exclude the ingress of rainwater, dirt into the installation space:

  • stick a vapor-permeable diffusion tape to the bottom seam from the street side;
  • lay the sealing tape over the street side of the spacer profile;
  • attach the ebb with screws to the substitute profile;
  • for sealing joints, sealing, use silicone or mastic.
  1. Install the windowsill.

Start work after polymerization of the seam. Cut a window sill of the desired size from the uPVC sheet (use a jigsaw or grinder). Optimal dimensions: front projection – at least 1-5 cm, but not more than 1/3 of the radiator outlet, side projections – 3-7 cm.

Fill up the free space under the windowsill with foam. To prevent it from rising during the expansion of the polyurethane, place a load on the surface.

At the last stage of the installation, silicone sealant is used to eliminate the gaps between the mating surfaces.

Installation of the frame without removing the glass unit (on the anchor plates)

The block is attached to anchor plates. One part of the plate is fixed on the profile, the other in the wall. The bend angle of the anchor plate can be selected according to the seam size. Mounting to the wall is carried out at least at two points; dowels with locking screws are used.

Advantages of using anchor plates:
  • the integrity of the frame is not violated: the profile does not need to be drilled;
  • there are special swivel plates for fastening windows of complex configurations (bending, triangular, polygonal);
  • the optimal type of fastener for houses of the old building, when the owners themselves do not know what the walls are made of, whether there is a void inside, whether there are other difficulties that prevent installation on anchor dowels.

The method is not suitable for installing window panels with an area of ​​more than 4 square meters. The plate may not support the weight of the structure.

Plate fixing rules:

  • plates around the perimeter are placed at least 1 m;
  • the distance from the corner is not more than 25 cm;
  • first of all, the central plate is attached exactly in the middle of the frame;
  • use self-tapping screws with a drill (marked “for metal”);
  • you need a gap between the profile and the wall within 2-3.5 cm. If less, form grooves in the slopes for the plates.


  • insert the frame, align the position with wedges, pads, building level;
  • fix the plates in the opening: for work on a brick, concrete base, take dowels 6×40 in size, wooden surfaces hold uPVC structures well on self-tapping screws 4.2×45;
  • fasten the plates in sequence: start at the lower left corner, then go to the right. Next, proceed with the middle and top fasteners.

The final stage

The final stage is the installation of elements that improve aesthetics and functionality. This includes:

  • decorative slopes: they can be made of sandwich panels in the color of the profile or in the form of a layer of gypsum plaster (can be painted);
  • children’s lock;
  • mosquito net;
  • cover strip – a decorative element for masking the seam;
  • intake ventilation valve: for continuous natural ventilation of the room.

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