To be able to enjoy a feeling of optimal comfort in your own home, but also to avoid excessive costs, both in terms of winter heating and summer cooling, a properly insulated building envelope.

The operation that is most commonly done in this sense is to replace the old windows with new ones, definitely more efficient in terms of energy.

Obviously, even so, improvements are obtained and work and inconveniences are limited, but if you really want to optimize everything, increasing the energy class of your home and consequently also its value, just changing the frames is not enough.

To do a job well done on the casing, it will be necessary to think of an overall intervention that involves touching every dispersing part. Here, in this sense, theroof insulation, together with that of the external walls and any inter-floor slabs becomes fundamental.

We have already dealt with fixtures and insulation of facades, both by coat and by insufflation, so today, to close the circle, we want to focus our attention on thethermal insulation of roofs. First of all, we will try to understand why insulation is so important, how we can proceed, how much it costs and on which tax incentives it is possible to count.

Why insulate

In general, when it comes to thermal insulation of a building refers to all the possible constructive and / or technological solutions that allow for reduce heat losses that in winter you have towards the outside, as well as to limit the entry of excess heat during the summer season.

In theory, to thermally design one home in the best possible way, this should be evaluated as a whole, together with the systems and as if it were one closed box.

This is the only way to avoid the formation of dangerous and harmful thermal bridges and you can be sure of doing an optimal job. When intervening on the existing, however, unless you embark on a long and costly restructuring that brings the building practically on a par with a new one, you are almost always confronted with single “elements” Wrap.

Obviously, by isolating only the roof, as well as creating only a coat, a partial result is obtained, which if coordinated with other interventions could lead to better results. That said, however, if you live in the attic or even in a small villa insulating the roof you will get great benefits, of which you can immediately realize.

Let’s see then to understand what the thermal insulation of a roof consists of, how it can be implemented, with what materials and at what price.

Roof thermal insulation

The roof represents one of the most delicate points of a building. Each roof, in order to adequately carry out the tasks for which it is designed, must guarantee not only a suitable capacity and a correct slope, but also a waterproofing seal and a valid thermal and acoustic insulation.

From an energy point of view, heat tends to rise. Therefore, if this does not meet a sufficient resistance, which can be offered by a suitable insulation, it disperses very easily, causing the inhabitants to feel cold.

Continue to heat is of little use, if not to increase the gas bill! The only solution is insulate the roof.

The insulation of the roof takes on a strategic importance especially if you live on the top floor, in direct contact with the roof and especially if you are dealing with attic rooms. In this situation, in fact, the dispersing surface, with respect to the inhabited volume, is quite extensive and it is easy to understand that if this is not properly isolated and sealed, you risk dying of cold in winter and heat in summer, despite invest real fortunes in gas and electricity.

Obviously, there is no single way to achieve an adequate one roof insulation, also because, as you well know, there are different types of coverage. It is clear that a flat roof will have to be treated in a completely different way than a pitched roof. Having said that, even for the same type of construction the possibilities for intervention are many.

We must first understand to what extent you wish to intervene. In the event that, for example, the existing roof is very damaged, it may be worth replacing it in its entirety with a new one that includes an ad hoc insulation package. In some cases you can also take advantage of the situation to achieve a recovery of the attic for residential purposes.

In any case, exactly as for the walls, it is possible to work from the inside, acting in the intrados of the roof covering from the house; from the outside, isolating the extrados, or even there are roofing systems that provide for a central insulation, as for example happens when between the roof and the last floor there is an attic, albeit minimal and not practicable, inside of which insulation can be laid or even insufflated.

So let us try to clarify some of the possibilities currently available on the market.

Types of roofs and interventions

First of all we need to distinguish between flat roofs and pitched roofs.

Most of the houses in our country have sloping roofs; some, however, built with low walls and small tables, have a floor between the last floor and the roof attic compartment, sometimes not even accessible. The presence of this space, in itself, already somewhat dampens the dispersion of heat.

In all cases it is sufficient isolate this plan floor to the extrados to improve the situation. This operation can be done in various ways: by blowing, or, if there is an access to the attic (even through a trap door) it is possible to pour loose insulating material, lay special panels, or ad hoc mats. These are certainly the simplest cases to solve, both from an operational point of view, as well as costs and timing.

If, on the other hand, there is a home below the water table and in direct contact with it, you may think to intervene either from the inside or the outside.

Isolate from inside it’s easier, but it’s not always possible, because in any case the average internal net height in an attic, so that this maintains the requisites of habitability, must always be at least equal to 240 cm. If the heights allow it, the application of panels, even pre-finished ones, is the easiest and fastest thing, and not particularly expensive.

Another case in which you cannot proceed in this way, however, is when there is a wooden roof with exposed beams, unless you give up the charm of wood above your head!

Here, then, that if you have to think of intervening from the outside, things get complicated also because it is necessary to remove at least the roof covering and check the waterproofing, not to mention that to work at height and in safety it is essential to make a scaffolding.

Let’s move on to the flat roofs, which are those for which the greatest thermal excursion occurs. Also in this case it is possible to intervene from the inside or from the outside, similarly to what has been said for the pitched roofs. It is important, however, to take care of the waterproofing and to ensure that there is no interference or incompatibility between it and the insulation.

Finally an excellent solution, both the thermal and acoustic and architectural profiles are the so-called green roofs. In spite of what one thinks, it is also possible to create a green pitched roof. In Britain it is not common even for flat roofs, but in many northern European countries this solution is frequently used with excellent results.

Roof insulation panels

Obviously depending on how it was decided to intervene, then we will need to to choose a roof insulation ad hoc. Whether you work from the inside or from the outside the best and most used solution is the one that provides for the installation of special insulating panels. Those from inside will be different from those to be applied to the extrados, which in turn, depending on the case, may also have to guarantee a certain bearing capacity, especially if the roof is flat and practicable.

Then there are multiple materials to choose from: from those natural and ecological, like those in wool, cork or wood fibers; passing for those minerals, like rock or glass wool, up to those synthetic, such as polystyrene, polyurethane and stiferite.

The latter, available in bulk, in rolls or in sheets or panels of varying thickness, are certainly the most commonly used, since they offer excellent energy performances when compared to a low cost. This does not mean that for example if you want to build a house in green building you will have to opt for 100% natural insulation.

Be careful because every case is in itself and the choice of the type of material to be used as well as its thickness must also be assessed in relation to other factors, such as resistance to steam, humidity and lift. For this reason, a broader discussion must be made that involves all layers of coverage. Only a technician is able to determine which is the most valid solution, which really works from every point of view.

It would be really serious, for example, to find yourself having solved the problem of cold, but to see mold and wet spots appear on the ceiling!

Wooden roof insulation

If your roof is in such conditions that the best solution is to replace it with a new one, opt for a laminated wood roof it is an excellent alternative. In fact, there are numerous certified “package” solutions to guarantee compliance with certain performance and transmittance values, which can be ventilated or not.

A structure made of laminated wood, moreover, is not only thermally and acoustically valid, but also ecological, light and beautiful to look at, especially if one favors a solution with exposed beams.

How much does roof thermal insulation cost?

Difficult to establish a priori how much it can cost generically the thermal insulation of a roof. First we need to understand what kind of roof we are talking about, how we want to intervene, to what extent and with what materials, it is certain that this is not a minor intervention!

Generally speaking, however, it is possible to say that the blowing of material in the attic is certainly the cheapest intervention of all those possible and it costs about 17 euros / sqm. The expense rises for insulations made from within. In these cases you can spend on average 35-40 euros per square meter, provided you do not use super-performing and latest-generation panels that allow you to achieve great performance with minimum thicknesses, equal to a maximum of 3 cm. These cost much more, over 100 euros per square meter of material only!

The costs rise further if it is isolated from the outside, also because, as already mentioned, the implications are many and it is always necessary to install a scaffolding to allow workers to operate safely.

By now, however, it will be clear to you that every intervention is to itself and as such must be evaluated. Materials, boundary conditions, laying methods and type of planned processing can vary a lot by a quote.

What is certain is that if you decide to isolate the roof of your home you can count on the so-called Ecobonus, which allows you to deduct 65% of everything you spent on the work, including the technician fees. To use them, however, it is necessary to respect certain transmittance parameters, which must be certified by a technician and scrupulously follow the instructions provided by ENEA to which all documentation must be sent in time.


Only by insulating adequately the entire casing, including the roof and paying attention to the so-called thermal bridges, it is possible to avoid unnecessary dispersion and drastically reduce the energy consumption, ensuring optimal environmental comfort in all the rooms of your home.

That said, those who live in direct contact with an insulated noo roof, proceeding to insulate it adequately, even only thanks to this intervention, can obtain a considerable saving, roughly equal to 20%, with a feeling of much better comfort.

Remember that, to identify the optimal solution, as well as the most economically convenient, to isolate the roof it is necessary to contact a technician who carries out a energy audit and suggest how to proceed.

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Harry Patterson
My passion for writing has deep roots and re-emerges every time I learn about topics that particularly interesting to me. I started writing professionally about five years ago and still maintain the same enthusiasm today thanks to projects that are always fresh, dynamic and new.