Insulation is the process of using special materials to protect a building from heat loss, moisture, noise or even fire. Simply put, it acts as a "shield" that keeps the heat in in winter and out in summer, while preventing problems such as dampness and mould on the walls. Insulation is extremely important because it improves the energy efficiency of the building and reduces heating/cooling bills. For example, an uninsulated roof can account for up to 40-45% of a home's energy losses. With proper insulation, these losses are reduced, better year-round temperature comfort is achieved and the structure is protected from weather damage.
There are different types of insulation, each with its own purpose and benefits:
Thermal insulation: this is the insulation that reduces heat transfer through the building envelope (walls, roof, floors). Thermal insulation helps to keep the house warm in winter and cool in summer, reducing the need for heating or air conditioning. With proper insulation, energy savings of 35-65% can be achieved, which translates into significantly lower electricity or fuel bills. In addition, it protects the structure from extreme temperature changes, reducing cracks due to contraction/expansion and prevents condensation of water vapour (which can cause damp).
Waterproofing / Waterproofing: This type of insulation is concerned with preventing the ingress of water and moisture into the building. It is mainly applied to roofs, foundations, basements and walls exposed to rain. A proper damp proofing ensures that there will be no leaks or moisture problems in ceilings and walls. The benefit is protection of the structure from corrosion, mold and water damage over time. A watertight building has a longer life span and requires fewer costly repairs in the future.
Soundproofing (Sound insulation): soundproofing aims to reduce the noise that passes inside or outside a room. It is made with materials that absorb or block sound waves (e.g. special foam materials, mineral wool, etc.). The benefit of soundproofing is a quieter and more comfortable living or working environment, free of disturbing ambient noise. Especially in apartment buildings or commercial premises, proper sound insulation can significantly improve the quality of life by providing acoustic comfort and privacy.
Passive Fire Protection: this is special insulation techniques and materials that protect the building from fire. For example, fire-resistant panels, special cladding on structural elements or insulation materials with high fire resistance. Passive fire protection delays the spread of fire in the event of a fire, giving valuable time for evacuation and fire brigade intervention. This type of 'insulation' is not about energy saving, but about safety - it protects human lives and property, and is often required by fire safety regulations in industrial or public places.
There is a wide range of insulation materials used depending on the needs of the project (thermal insulation, waterproofing, soundproofing, etc.).
Some of the most common insulation materials are:
Mineral wool (glass wool & rock wool): these are fibrous insulation materials. Glass wool is made from glass fibres, while rock wool is made from natural rocks that have been melted and turned into fibres. Both materials are excellent thermal and sound insulators and are non-flammable (fire-resistant) due to their inorganic composition. They are usually available in the form of rolls or sheets and are installed in walls, attics, floors or ceilings.
Polystyrene (expanded EPS & extruded XPS): is a foam plastic material, also known as Styrofoam in its expanded form. Expanded polystyrene (EPS) boards are lightweight, white, and are often used in exterior wall insulation (thermal insulation) or under roofs. Extruded polystyrene (XPS) is denser and more moisture resistant, usually green/blue in colour, suitable for thermal insulation of roofs, foundations and general areas with loads or moisture. Polystyrene offers very good thermal insulation capacity at low thickness and has low water absorption, making it ideal for applications in contact with moisture.
Polyurethane (polyurethane foam): one of the most effective thermal insulation materials, thanks to its closed cell structure containing air. Polyurethane foam can be applied in situ by spraying (spray foam) onto roofs, attics or walls, creating a single insulating layer without joints. It expands and fills cracks, acting as both an insulator and a sealant (as it leaves no gaps). There are also ready-made rigid polyurethane boards (PIR/PUR boards) that are installed on roofs or floors. Polyurethane has a very high thermal resistance index (R-value), offering great energy savings in a small material thickness.
Asphalt membranes (bituminous sheets): these are sheets of modified asphalt with embedded reinforcement (polyester, fibreglass, etc.), mainly used for waterproofing roofs. Bitumen sheets are applied by heating (flame) to the surface of the roof, creating a waterproof layer that prevents rainwater from penetrating. They are usually combined with thermal insulation boards underneath (in conventional insulation) or on top (in inverted insulation), so that the roof also has thermal insulation protection. They are UV resistant and have a long life span, protecting the building from leaks and moisture.
Missing sealants: In addition to asphaltic sealants, there are liquid sealants that are applied by roller or spray. Examples are polyurethane membranes (e.g. Hyperdesmo), acrylic elastomeric paints, cementitious coatings, etc. These create an elastic, waterproof film on the surface, without joints, ideal for complex roof morphologies or places where bituminous coatings are difficult to apply. They are often used in combination with fiberglass mesh or reinforcement fabric for greater strength. Their advantage is that they can reach and seal every nook and cranny and detail, ensuring a complete seal.
Notes: Each material has its advantages and disadvantages, and the choice of the appropriate insulation material depends on the application (e.g. roof, wall, piping), climate, budget and project requirements. Often, materials are combined in an integrated insulation - e.g. thermal insulation boards together with an asphalt membrane on the roof - for an optimal effect of thermal insulation and damp-proofing at the same time.
Insulation is applied in various parts of the building, i.e. everywhere where there is a possibility of heat loss or moisture ingress. The main areas that need insulation are the following:
Terrace / Roof: The roof of a building is one of the most important places for insulation because it receives direct sun, rain and cold. Without insulation, the roof allows heat to escape in the winter and penetrate in the summer, causing major energy losses. Roof insulation (a combination of thermal insulation and damp proofing) keeps the house cool in summer and warm in winter, while protecting against rain and dampness. On pitched roofs, the insulation is placed under the tiles or on top of the attic ceiling.
Exterior Walls / Facade: Walls surround the bulk of the building and without insulation allow heat to pass through easily. With external thermal insulation (thermal facade), insulation boards are placed on the outside of the walls and covered with plaster, drastically reducing heat loss. This also eliminates thermal bridges (places where heat "slips through", e.g. columns/beams), improving energy efficiency. Insulation can also be applied internally to walls (in special cases), but external insulation is preferable to fully protect the building element and keep heat out in summer.
Floors and Ceilings: Surfaces such as the floor above an unheated space (e.g. above a pilotis, garage or basement) can be insulated to prevent the space above them from cooling. Floor insulation is either done from below (in the ceiling of the space below) or during the construction of the floor with insulating material. Also, the roof of an unheated basement or attic is insulated to reduce the cold rising to the upper levels. In general, adding insulation to floors/ceilings adjacent to cold spaces or ground increases comfort and reduces losses. Insulating the attic (if there is no habitable space) is also important, as an uninsulated attic acts as a "chimney" that loses heat to the environment.
Underground / Foundations: The surfaces of the building that are in contact with the ground need damp-proofing to protect them from soil moisture. Waterproofing membranes or coatings are applied to basement foundations and walls to prevent soil water from penetrating the concrete (thus preventing rising damp and mould in the basement space). In addition, thermal insulation material can be applied to the exterior basement walls to reduce the amount of cold transferred from the ground into the building. This is particularly helpful in areas with very low temperatures, maintaining a more constant temperature in the basement and ground floor.
Frames (Doors & Windows): although not "insulation" in the traditional sense, it is worth mentioning that modern thermal insulation frames (double/triple glazed windows, frames with thermal break) contribute significantly to the overall insulation of the building. A large proportion of losses occur through windows and doors, so replacing old frames with energy efficient ones reduces cold air currents and keeps heat in. Combined with structural insulation, good windows complete the energy shielding of a home.
In short, a complete insulation must cover the entire building shell: roof, walls, floors, foundations and openings. This ensures maximum energy savings, comfort for the occupants and protection of the property from damage.
The process of applying insulation involves several stages and may vary slightly depending on the type of insulation (roof, wall, etc.). In general, however, the following steps are followed:
Surface Control and Preparation: Before any insulation work begins, the existing condition is assessed and properly prepared. For example, in rooftop insulation, the first step is to thoroughly clean the surface - removing debris, dust, soil or mold - and repair any cracks or damage to the concrete. A pressure washer is often used to wash the roof and remove loose materials. Also, the gutters are checked that they are not clogged. This phase is critical: a clean, dry and smooth surface ensures that the insulation materials will adhere properly and perform to their maximum.
Primer application: after cleaning, a layer of primer is usually applied on the surface (in case of roof or wall sealing). The primer is a preparation material that improves the adhesion of subsequent layers of insulation materials on the substrate. It is spread over the entire surface and, once dry, creates a suitable base for the membranes, paints or adhesives of the insulation boards to 'bond' to.
Placement of Insulation Materials: After the surface has been prepared, the main work of insulation is done by placing the appropriate materials:
In roof insulation: Since we are talking about thermal insulation of a roof, the insulation boards (e.g. extruded polystyrene or rock wool) are placed on the surface. The boards are cut to the correct dimensions and spread out to cover the entire roof. They may be fixed with an adhesive or simply applied freely (if it is inverted insulation where they will be covered with gravel). Alternatively, in difficult areas or for additional waterproofing, spray polyurethane foam can be used to fill any gaps.
In external wall insulation: here, the thermal insulation boards (usually expanded polystyrene or rock wool) are bonded to the external walls with a special adhesive. After the entire surface has been covered, the boards are additionally fixed mechanically with plastic plugs (nails with washers) for security. After the plates are installed, a layer of thin plaster (adhesive) is applied with an integrated glass mesh to reinforce the surface and prevent cracking.
In interior insulation or other applications: A similar principle is followed - insulating materials (e.g., rolls of fiberglass in the attic or between joists, sheets of foam behind drywall, etc.) are placed so that they cover the surface being insulated without gaps.
Waterproofing and Sealing: if the application includes waterproofing (mainly on the roof or in foundations/basements), the next step is the creation of the waterproof "barrier". In the case of the roof, over the insulation boards (in conventional insulation) or directly on the substrate (in case we want to waterproof first) the sealant is applied. This can be done in two basic ways:
Adhesion of asphalt sheets: pieces of asphalt membrane are heated with a flame torch and glued onto the surface (or onto the insulation boards if they are special for adhesion). The sheets are placed overlapping each other to form a single waterproof layer. Particular attention is paid to the meeting points (joints, corners, pipe ends) to ensure that they are fully sealed.
Refillable sealant: Alternatively, liquid sealant (e.g. polyurethane or acrylic membrane) is applied by roller or spray. Usually two or more coats are applied to allow the material to form the correct film thickness. Each coat must be allowed to dry before the next. This method creates an elastic, monolithic sealant layer with no joints.
In many types of roof insulation, thermal insulation is combined with waterproofing - e.g. in an inverted insulation, we first waterproof the roof with bitumen and then place thermal insulation boards on top, covered with geotextile and gravel (to protect them). This way, the waterproofing stays "under" the insulation. Conversely, in conventional insulation, the thermal insulation layer is put in first and the bitumen is glued on top.
Final Finish and Control: After the layers of insulation are completed, any finishing work is done for protection and aesthetics:
On roofs, a final protective coating is often applied over the waterproofing (e.g. a cold-coloured acrylic paint, gravel if it is inverted insulation, tiles if it is a walkable roof). This final stage protects the layers of insulation from UV radiation, mechanical stresses and gives a presentable appearance.
On exterior walls with a thermal facade, after the insulation boards and the grid are installed, the final plaster (usually ready-made plaster based on acrylic or silicone materials) is applied in the desired texture and colour, so that the appearance of the building is uniform and protected.
Next, the completed insulation is inspected to ensure that there are no uncovered points or defects. For example, on the roof, we check that all bitumen joints are properly sealed, or that the coated material covered every corner.
Upon completion of all the above steps, the insulation of the space is put in place. A properly executed insulation process ensures long-term performance - meaning that your home will remain warm, dry, and comfortable for many years without problems. It is always important that the work is carried out by qualified crews and with certified materials, so that specifications are met and guarantees are provided for the result.
The cost of insulating a roof can vary significantly depending on a number of factors, such as the surface area (square meters), the type of insulation to be done (waterproofing only or thermal insulation), the materials to be used and the condition/preparation that the roof may need. Typically, insulation companies will quote per square metre (€/sq m) for the project.
Costs are influenced by factors such as:
the area of the terrace (very small areas have relatively higher costs per sq.m, (very small areas have a relatively high cost per m2 because there are fixed workshop costs, while on larger surfaces the cost per m2 may drop), the condition of the substrate (if the roof has a lot of damage, extra work/materials are required for preparation), the thickness and type of insulation (e.g.e.g. 5 cm XPS vs 10 cm rock wool have different costs), the type of waterproofing (bitumen, polyurethane membrane, EPDM etc - each with its own price),
the height of the parapet and the details (more parapet metres or several gutter spouts mean more work/material), any difficulty in accessing the roof (e.g. if a crane is needed to lift materials), etc.
Therefore, for an accurate costing, it is best to ask for quotes from reliable insulation companies. They will do an inspection of your premises, assess the needs (whether you need thermal insulation or just waterproofing, what materials are appropriate, etc.) and give you a specific price. Remember that insulation is an investment that pays for itself over time through savings in energy costs and damage avoidance, so it's worth prioritizing quality, not just the lowest price.
