How to insulate a balcony: a step-by-step guide

1. Understand the basics

How does a balcony differ from a loggia

First of all, let's clearly separate these concepts. Both are glazed, so most people call the resulting space a balcony, although this is incorrect. And some mistakenly believe that if you install windows on the balcony, it automatically turns into a loggia.

The key difference between the two structures is that the balcony has no walls and protrudes beyond the facade, while the loggia has side walls and, on the contrary, is recessed into the building. In other words, the outside air acts on the balcony from three sides, and on the loggia - only from one or two, if the apartment is angular.

What result to expect

You can insulate both, but the final effect will vary greatly. A well-insulated loggia is no different from a room. With a heat source, it becomes a full-fledged living space for year-round use.

Due to the lack of solid walls, the thermal resistance of the insulated balcony is much worse - it is comfortable to stay there until late autumn. A sufficient level could be achieved with an additional layer of thermal insulation, but this is not rational due to the small area of the room. After warming, there will be almost no free space.

What's with the glazing

Since 25% of heat loss falls on windows, it makes sense to take on the insulation of a loggia or balcony only if there are energy-saving windows. If wooden frames with one glass are installed, you will first have to replace them with modern ones.

Double-glazed windows with a higher thermal resistance weigh a lot and can only be installed on loggias. Balcony floors have a weak bearing capacity, and most likely it will not work to mount such windows there.

2. Consider the design

Before starting work, you need to decide on the type of insulation, choose the option for finishing the walls and finishing flooring, and also decide how the room will be heated. All this will determine the design and the algorithm for its installation.

Insulation

Since the insulation of a balcony or loggia is carried out from the inside, it is important to use a vapor-proof material in order to avoid the formation of condensation and the appearance of fungus.

Extruded polystyrene foam (EPS) is best suited for this. When installed with sealing joints, it allows you to make a kind of thermos out of the room, which will retain heat well by cutting off the external cold. At the same time, with EPS, you can achieve sufficient thermal insulation, taking a minimum of precious space from the room.

Some consider styrofoam toxic. This is not entirely true. The material is indeed flammable and, when heated above 60 ° C, emits harmful substances, but this does not make it dangerous, since the EPS is always covered with a finish.

Wall decoration

After good insulation on the loggia or balcony, you can apply any type of finish. Depending on the chosen coating, the technology of work on thermal insulation is slightly different.

Wooden lining, PVC or MDF ‑ panels - for mounting to a wall, you will need to first make a crate.
Decorative plaster or putty followed by painting - this type of finish can be applied directly to the insulation.
Wallpaper - the easiest way to glue on drywall, fixed on a wooden crate.

Flooring

The floor of the insulated loggia is no different from the floor of the room, so all existing topcoats can be used there. However, for each type, you will need one or another version of the subfloor.

Laminate, linoleum, carpet are laid on plywood sheets, chipboard (chipboard), DSP (cement chipboard) or OSB (oriented strand board) fixed on top of wooden logs.
Tiles and porcelain stoneware are laid on a concrete screed.

Floor slabs of balconies have a low load-bearing capacity, therefore, only floors on wooden logs are allowed on them. In addition to this, on more durable loggia foundations, you can also pour a screed for laying tiles.

In both cases, if desired, you can equip an electric floor heating system. The only difference is that for the construction on the logs, a film infrared floor is used, and for the screeds, a heating cable or heating mats.

Heating

It is important to understand that insulating a balcony or loggia will only prevent the walls from freezing and slightly increase the temperature compared to the street temperature. To maintain a comfortable microclimate in winter, you cannot do without a heating source.

There are three main ways to heat a room:

Electric underfloor heating is the most costly and difficult to install option, but at the same time the most effective and convenient.
Convector - a heater installed against an outer wall can be turned on only on the coldest days or only when there are people in the room.
Central heating radiator - according to the law of the RF LCD, article 25. Types of reconstruction and redevelopment of premises in an apartment building are prohibited from transferring the device to a loggia or balcony, but if the partition is removed or the door is constantly open, the battery will cope with heating even from the room.

3. Prepare surfaces

Take things out, remove shelves, hangers, and other items. Remove old paint and plaster from the walls. If there are foci of lesion with a fungus, remove it and carefully treat the places with a special antiseptic, and then dry all surfaces well.

To prevent blowing out, seal all gaps around the perimeter of the fencing slab, as well as at the junctions to the side walls, floor and ceiling. Remove the old plaster from the joints and fill them with polyurethane foam.

The bottom line is to cut off any cold air flows from the street and make the room as tight as possible.

4. Install the sockets and lighting

If you plan to use the insulated space as a study or recreation area, you must pre-mount the electrical wiring. To do this, install sockets, lighting and switches in the right places.

It is better to run the cables along the inner wall adjacent to the room. It is not insulated, so all wiring can be easily hidden inside the frame or plaster layer. Sockets and lighting can be plugged in from the nearest outlet in the room. But to power the warm floor, it is advisable to conduct a separate cable from the distribution board.

5. Learn the technology of working with EPS

Expanded polystyrene is sold in the form of slabs with a size of 60 × 120 cm and a thickness of 20 to 150 mm. The sheets have an L-shaped lock along the contour, which simplifies installation and prevents blowing through the joints.

There are different ways to fix the EPSP to the walls. The most common is glue-foam in cylinders, which is applied around the perimeter of the sheet and in the middle. Another option is fixing in the corners and in the center on dowels-umbrellas with a plastic or metal core. Also, expanded polystyrene is attached over the entire area of the sheet to adhesive mixtures for insulation.

To form a single contour of thermal insulation, it is necessary to seal all joints. It is important to leave gaps of 10-15 mm near the walls in the corners, under the ceiling and near the floor, so that later they can be filled with polyurethane foam. It is recommended to coat the joints in the locks between the plates with glue-foam or seal them with foil tape.

The required thickness of insulation can be achieved either with one sheet or with a combination of two. In this case, the second option is even preferable, since the fragments of expanded polystyrene are tightly adjacent to each other and form a single layer, and due to the displacement of the joints between the plates, maximum protection against blowing can be achieved.

After the end of the work, an unbreakable structure should be obtained, where each sheet of EPSP fits snugly to the neighboring one, and all joints between them in the corners, under the ceiling and at the floor are sealed with polyurethane foam.

6. Insulate the parapet

The fence slab borders the street and is exposed to the cold air the most, so the maximum insulation thickness here is 80 mm. It is better to use not one 80-mm sheet, but a “pie” of slabs: 50 + 30 mm.

If the dimensions allow, the wooden lathing is mounted on top of the second layer of EPSP, fixing the bars with anchors or dowels directly through the insulation. When the width of the window sill is limited, the crate is fastened with 50 mm expanded polystyrene foam, and the second layer of insulation is placed between the frame bars.

If plaster is chosen as the finish, you can do without the construction of a frame. In this case, the mixture is applied directly to the surface of the EPS. For better adhesion, the sheets must be trowelled or scratched with a regular hacksaw.

7. Insulate the walls

For walls, a 50 mm EPS layer is sufficient. The work is done in the same way. If necessary, the sheets are cut to the desired size with a sharp knife. To join the pieces to each other, an L-shaped lock is formed at their ends with the same knife.

It is better to insulate it in two layers (30 + 20 mm), and fasten the frame over the EPS. But if the window is installed without accessories and the space is limited by the width of the frame, the second layer of expanded polystyrene can also be laid between the frame bars.

If you are going to plaster the walls in the future, then the crate is not needed. It is enough to fix the sheets and make their surface rough with a grater or hacksaw.

8. Insulate the ceiling

The ceiling borders on the neighbor's apartment, not on the street. Therefore, the same EPS layer is sufficient here as on the walls - 50 mm. Laying is done according to a familiar principle. Attachment of your choice: glue-foam, dowel-umbrella, glue mixture. Expanded polystyrene is a very light material and reliably adheres to the ceiling only with glue.

When installing, pay attention to the height of the windows. If the frame is installed under the ceiling itself without additional profiles, then due to a thick layer of insulation, the window sashes may not open. Take into account the thickness of the battens and finishing so that after installation there is a gap of at least 5–7 mm to the sash.

9. Insulate the floor

For thermal insulation of the floor, an EPSP with a thickness of at least 50 mm is required, and better - 80 mm in two layers. Extruded polystyrene foam has a high density and can withstand a load of up to 30 tons per square meter, therefore it can serve as the base of the floor.

After installation on EPSP, it is enough to lay plywood, chipboard, DSP or OSB - and on top you can lay a finishing floor covering like laminate or linoleum. When installing a film underfloor heating, you first need to lay penofol or another heat-reflecting substrate.

For laying tiles or porcelain stoneware, a reinforced cement screed is poured directly on the EPSP, into which, if desired, you can install a cable heated floor or thermomats. If the heating elements have a small thickness, they can be easily laid in the adhesive layer when laying the tiles.

The floor on the balcony or loggia is always lower than in the room, so many people prefer to bring them one level and remove the step. This is done using a log from a wooden bar 50 × 50 mm or 40 × 40 mm.

First, transverse joists are laid with a pitch of 40–60 cm and fixed to the slab with anchors. Then the gaps between them are filled with insulation and foamed, and longitudinal logs with a similar pitch are attached on top and leveled. Next, the second layer of insulation is laid with foam filling and plywood or other sheet material.

ten. Complete the finish

At the very end, the ceiling, walls and floor are trimmed. If plaster is selected, then a reinforcing mesh is glued to the sanded EPSP surface, and then two layers of plaster and paint are applied.

When cladding with clapboard, plastic or MDF panels, molded materials are attached to the wooden frame on the walls and ceiling.

For wallpapering, the easiest way is to sheathe the walls with moisture-resistant plasterboard. Use the crate as a frame, seal the joints between the sheets with putty and, after priming the surfaces, glue the wallpaper.

11. Install the floor covering

The final stage of finishing is the installation of the finishing floor. Laminate is laid on the previously prepared base or linoleum is laid. If a warm floor is planned, then it is first installed. Next, the skirting boards are mounted.

The exception is tiles. Due to wet processes during installation, it is better to install it at the stage of floor insulation and before starting work on the walls.