How To Make A DIY Thermal Coat

Everything you need to know about the thermal insulation system, from the different possible solutions to the costs and methods of self-construction.

The external insulation of the house, commonly called house insulation or thermal insulation, has the purpose of reducing the dispersion of heat and the formation of thermal bridges in order to increase energy savings. The system can be of two types: internal external insulation , created inside the house, and external external insulation .



Both systems have their pros and cons of course, so let’s go and examine them a little more in detail to understand which of the two is the most suitable for making a DIY thermal coat .

The insulation of external surfaces


The thermal coat applied on the external facades of the house allows to dispose of the overheating of the walls during the summer season and to reduce the thermal dispersion during the winter season, as well as to eliminate the phenomenon of condensation humidity; it is usually made with external insulating panels composed of sintered expanded polystyrene, which in addition to having excellent thermal insulating properties is also fireproof.


The further advantage of expanded polystyrene is that it offers a fair degree of sound insulation that will allow you to do without headphones when you want to listen to music at a high volume; because even the best earphones start to feel annoying if worn for too long.

The insulating panels of this type are available in different thicknesses starting from 60 up to 120 millimeters, depending on the climatic zone where they are to be installed, and can be used to cover both the walls and the roof.

External thermal cladding: disadvantages


Since the intervention takes place on the external facades of the building, the prospectus of the latter is modified therefore, according to the regulations in force in the municipality of residence or in the condominium regulation, the intervention could be subject to constraints or restrictions. Precisely for this reason, and due to the fact that the panels are in direct contact with atmospheric agents, it becomes mandatory to contact a specialized company capable of carrying out the work in a workmanlike manner, complete with certifications.

Consequently, another disadvantage of the exposed facing thermal insulation system is the price ; Obviously, the external cladding panels have prices identical to those for internal because with the exception of those in sintered expanded polystyrene, which are used almost exclusively for external installation, there are generally no differences and the thermal insulation panels can be installed both internally and externally.



What has the greatest impact on the final cost, therefore, is that the overall external surface to be coated is higher than the internal one. In other words, the purchase of a greater quantity of materials is required, to which is then added the further increase in installation costs.


The internal solution


What penalizes the external solution the most, in addition to the cost of the thermal insulation system, which is higher, is the fact that the installation intervention which must necessarily be carried out by a company and that the intervention of a professional is also required to direct and certify the works.

If the insulating panels are to be installed on the internal facades of the walls, however, the situation changes radically; in this case there are no particular constraints, except the presentation of the CILA where required.

The do-it-yourself intervention is further facilitated for those who have access to a concrete mixer and other necessary equipment; it will be enough to buy the panels and materials for the construction of the thermal coat.

It is very important to remember, however, that the realization of the do-it-yourself thermal insulation system cancels any possibility of obtaining tax deductions, as one of the requirements for accessing the bonuses is the certification that the work has been carried out according to the regulations in force.

The cost of materials


The prices of the thermal insulation system are calculated per square meter, and generally include both the materials and the installation; in the case of do-it-yourself interventions, therefore, the expense will be limited exclusively to the materials.


The following table shows the cost variations per square meter depending on the type of insulating material, which can be polystyrene, polyurethane, rock or glass wool, calcium-silicate, wood fiber, cork or airgel.

Returning to what was previously mentioned on the costs of the external thermal insulation system, the latter is more expensive because the price of the material and installation must be added to the price of the scaffolding rental, which varies from 10 to 15 euros per square meter, and the parcel due to the technician in charge of the supervision of the works who must necessarily be a professional: engineer, architect or surveyor.

The presence of the construction manager is compulsory, as he must certify that the works are carried out in a workmanlike manner and that the changes to the prospectus of the building fall within the regulations in force in the Municipality of residence where it is located.

Tax deductions


If the thermal insulation system is installed by a specialized company, it is possible to access the restructuring bonus and have the opportunity to deduct 50%, 65%, 70% or even 110% of the purchase and installation costs, depending on the specific cases.

The maximum expenditure ceiling, in this case, is 40,000 euros for each individual property subject to the renovation, but in the case of the Superbonus the ceiling rises to 60,000 euros.

To obtain the bonus and the related tax deduction, however, it is necessary to certify that once the intervention has been carried out, the U thermal transmittance values ​​are equal to or lower than those reported in the Mise decree of 6 August 2020.

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