Is it possible to insulate the loggia only partially and how to avoid condensation?

Good afternoon, Vitaliy. Let's point by point:

1. Much depends on the windows. There are two types of sliding systems: sliding (cold) and a warm sliding system, most often with Roto fittings. On the photographs attached by me, pay attention to the difference in the principle of work. If you have a slide system installed, you can’t achieve the effect of a warm loggia. Guaranteed will be a strong condensation on the glass. The result is one: a large amount was spent on insulation without the required result. If a warm system is installed, then it is possible to achieve the effect of a thermos and get additional living space.

At the window installation stage, it is desirable to provide for the installation of an additional PVC profile at the top of the entire width of the window. Depending on the provided insulation of the ceiling, select the height of the expander 60-100 mm.

2. Insulate only the floor and the parapet will not be enough. Due consideration should also be given to walls. It is better to use, instead of polystyrene, extruded polystyrene foam. The most important criterion for selection is the density indicator, the higher the number, the higher the coefficient of heat transfer resistance. The name of the manufacturer does not play a role. A complete list of materials for insulation from the inside is presented in this article on our website.

3. Paint and existing mold should be removed before applying the antiseptic primer. Carry out the processing in two stages. It will help here this article.

4. Removes all excess around the perimeter, including the cement baseboard. This is done to eliminate bridges of cold. The resulting cracks in the corners are removed from the debris and blown out with foam.

5.Regarding the use of vapor barrier - extruded polystyrene foam has zero vapor permeability. Therefore, to carry out this type of work is not necessary.

6. For a more convenient installation and maximum thermal insulation, choose a heater with a lock. Plan the subsequent wall decoration, if it is a putty with painting, take the option with the applied grid. Styrofoam is attached to the walls in two ways: using parachutes or glue. The material has a low weight, so fixing with glue is the best option.

On the floor, install logs from bars (previously treated with an antiseptic for wood), in increments of the size of expanded polystyrene. Naturally, at this stage it is important to maintain the level, this will be your basis for flooring. It is possible to completely eliminate the cold bridge at the joints of the material by scraping the seams with a knife and slightly expanding them, go through the mounting foam.

More useful information and other ways can be found in this article.