How can you insulate a 1990s house from the inside without renovating the entire façade?

Measure the thickness and carry out the necessary exploratory openings. Check the area under the window, the junction with the ceiling and the bottom of the wall. If the layers differ between rooms, do not apply one result to the whole house. The wall by the garage, the extension and the heated living area must be assessed separately.

The answer should come from the building balance and the technical condition. Replacing the insulation of one wall may have a limited effect if large losses remain through the roof or leaky openings. On the other hand, a cold reveal may need attention even when it is not the largest surface.

Set the order based on the actual problems. Active leaks and damage are dealt with before insulation. Do not promise yourself a specific reduction in bills based on the lambda of the material alone. Energy consumption also depends on heating, ventilation and how the house is used.

Draw the future wall face including the finish. Add space for cables and any supporting frame. In a small bedroom, even a few centimetres can change the width of the passage by the bed. Before choosing the board format, also check whether the boards can be brought in through the stairs.

Measure the window sills, balcony doors and the distance to the radiators. It must be established whether the existing elements will be moved or replaced. The cost of these works is often overlooked in the first quote. A full drawing of the room allows variants to be compared in terms of space and scope of renovation.

Ceilings and transverse walls interrupt the simple layout of internal insulation. Insulating a large field alone does not ensure uniform temperature in all corners. Details are needed that arise from the assessment of the specific structure. They should not be selected solely on the basis of ease of board installation.

Also check the lintel and the band below the window. A local lack of space may require a different solution than the rest of the wall. Changes in thickness must be recalculated. Otherwise, after renovation, the cold section will remain hidden behind the new finish, and the cause of the problem will not disappear.

Insulation from the inside reduces the heat supply to the old masonry. This changes its temperature and drying conditions. The entire cross-section is subject to assessment, including existing façade coatings. The actual humidity of the rooms and the heating method must be taken into account.

If a layer with high vapour resistance is used, it must have continuous connections. The airtightness of corners and installation penetrations is as important as the surface of the board. With an uncertain layout, a more detailed moisture analysis may be necessary. A simple U-value result does not confirm the safety of the renovation.

First develop the whole plan, and only then choose the order of rooms. Ending the insulation halfway up an external wall creates a new thermal boundary. It is necessary to anticipate how it will perform until the next stage is carried out. A random break should not remain a permanent detail.

Coordinate electrical work, heating and floor finishing. Openings in the airtight layer are easier to resolve before installation than after painting. At the acceptance of each stage, document connections that will be concealed. This way, the next team will know the actual course of the layers.

In addition to insulation, include wall preparation, reveal finishing, installation modifications and new finishing. Also include the removal of skirting boards and the restoration of ceiling connections. A single rate per square metre of material does not cover such a scope.

Ask for the solutions in difficult places to be recorded. The offer should correspond to the same design that was used for the calculations. After renovation, check the operation of the ventilation and observe the corners during the cold season. The use of the building remains part of the operating conditions of the new partition.