If you've come this far, it's probably because you're looking for clear, definitive answers on how to optimize your home's thermal insulation by choosing between XPS, EPS, or rock wool. In this guide we will take an in-depth look at the properties, advantages, disadvantages and applications of these three key materials., taking advantage of all available and up-to-date information so you can make the best decision in terms of both efficiency and cost.
The choice of insulation material not only influences the comfort of your home, but also determines its energy efficiency, sustainability, durability, and even fire safety. We tell you everything you need to know by comparing XPS, EPS and rock wool in a rigorous but close way, with clear language and a practical approach., so you can make the right investment in your home renovation.
XPS, EPS, and rock wool: what are they and why choose them to insulate your home?
Energy efficiency and comfort require the correct selection of insulation material. Current construction systems usually use panels or plates of XPS (extruded polystyrene), EPS (expanded polystyrene) or rock wool. for its technical features and value for money.
Each of these materials is manufactured differently and has specific properties. XPS is obtained by extruding polystyrene under pressure, resulting in a rigid, homogeneous, closed-cell foam.EPS, on the other hand, is obtained by expanding small beads that are fused together by heat to create a granular block, with a large amount of air inside. Rock wool is made by melting and fiberizing volcanic rocks and is available in panels, blankets or even in bulk..
The decision between one material or another should be based on factors such as Thermal insulation level, mechanical resistance, moisture and fire resistance, ease of installation, cost, sustainability and acoustic requirements.
Advantages and disadvantages of extruded polystyrene (XPS)
XPS stands out for its durability, mechanical resistance and excellent protection against humidity.It is used in a multitude of construction solutions, especially in flat or pitched roofs, foundations, and exterior facades, as it withstands loads, compression, and direct contact with moisture well.
- It allows to eliminate internal condensation thanks to its low breathability., preventing the appearance of damp and pathologies in buried walls or in contact with the ground.
- Its homogeneous and closed structure provides high impermeability and great thermal insulation.This feature is key for roofs or areas where maximum protection from the elements is required.
- It suffers little mechanical deformation, making it suitable for installation on floors, roofs or facades of buildings exposed to significant loads.
- Usually available in different colors, thicknesses and formats, which makes it easy to adapt to each construction project.
Despite its strengths, there are points to keep in mind:
- Price higher than EPS, becoming more expensive the higher the density of the panel and, therefore, its insulation and resistance capacity.
- Lower performance as an acoustic insulator Compared to other materials, such as mineral wool, it's not the best option if you're looking to reduce noise.
- Low vapor permeability, which requires good ventilation in the home to avoid air quality problems.
XPS always complies with European regulations (UNE-EN 13164) and Spanish regulations for thermal insulation., ensuring its suitability for outdoor applications and SATE systems (external thermal insulation).You can find more information about its technical properties here..
EPS: the lightweight, versatile and economical insulation
EPS is known for being a lightweight and versatile material.It is used both in rigid panels for exterior insulation systems (ETICS) and in the form of bulk spheres for blowing into air chambers.
- It offers a very good quality-price ratio., making it one of the most widely used insulators in new construction and renovation.
- Easy to install, cut and handle, allowing complex shapes and adapting to different construction solutions.
- Excellent thermal insulation (its composition can reach up to 98% air), it is very light but effective.
- Water and mildew resistant, although less waterproof than XPS, it withstands ambient humidity well.
- Versatility of formats: panels, sheets, blow-molded beads or products combined with others such as laminated plaster.
- Lower mechanical resistance compared to XPS, which is why it is less recommended for floors or areas with high loads.
- Shorter lifespan under extreme conditions or under continuous compression.
- From an environmental perspective, its recycling is more complicated than rock wool, although there are recovery initiatives..
EPS is often used when a lightweight, easy-to-install, adaptable and especially economical solution is sought., being the most common material in SATE systems according to various associations in the sector.
Rock wool: total insulation and fire protection
Rock wool It is one of the star materials in thermal and acoustic insulationIt is obtained from molten basalt rock, presenting a very long life cycle and high fire resistance (it is non-combustible and does not release toxic gases). We expand the information about its characteristics here.
- Great thermal and acoustic insulation capacity, being one of the preferred materials to combat humidity, regulate temperature and improve interior comfort.
- Regulates water vapor and helps the home breathe, preventing condensation and mold growth.
- Excellent fire retardant properties, being one of the best options in security.
- versatile format: Available as a rigid panel, blanket, fleece or even in bulk.
- Maintains its properties intact for decades, which represents a long-term investment.
- It allows to insulate both interior walls and facades as well as roofs and floors., adapting to any part of the home.
- Sustainability options: It is made from natural raw materials and is usually recyclable.
- Higher price than polystyrene.
- Installation that requires some precautions (gloves, mask) due to their fibrous nature.
Technical comparison and key properties of the three materials
To make the right decision, it is important to analyze the properties of each material in detail:
- Thermal conductivity (λ)XPS and EPS offer low values, with XPS being more efficient at lower thicknesses. Rock wool also insulates very efficiently, although it requires slightly more thickness.
- Thermal resistance (R): Directly related to the insulation provided per square meter and thickness. All are compliant if sized correctly.
- Behavior towards water vapor and humidity: XPS is practically waterproof, EPS is resistant but not that much, and rock wool regulates moisture, being breathable.
- Fire resistanceRock wool stands out as non-combustible, while XPS and EPS must be used according to regulations to ensure safety.
- Acoustic isolationRock wool wins by a landslide, but EPS also helps in air chambers or double systems.
- Mechanical strengthXPS is the most robust; if you're looking for support for floors, roofs, or walls in contact with the ground, this is your choice.
- Durability: All of them maintain performance for years if properly installed. XPS and EPS can degrade under UV radiation if exposed, and rock wool is very stable over time.
- Sustainability and recyclingRock wool is more environmentally friendly, but there are polystyrene manufacturers that are making progress in recycling and reducing emissions.
The final decision will depend on your budget, the area's climate, regulatory requirements, the location of the insulation (interior, exterior, floor, roof), humidity levels, acoustic requirements, and the priority between sustainability, cost, and durability.
Strategic areas of the home and how to choose the best material
The greatest energy savings and thermal comfort are achieved insulating critical areas of your home: facades, roofs, exterior walls and floors in contact with the ground. Each area may require a different solution:
- Facades and exterior wallsThis is where the greatest heat loss occurs in winter and where the greatest amount of heat enters in summer. ETICS with XPS or EPS is very common; rock wool is the best option if you're looking for acoustic insulation and fire resistance.
- Roofs and coversXPS is highly recommended if waterproofing is key (flat roofs, terraces). For pitched or tiled roofs, EPS or rock wool are effective and acoustically superior options.
- Floors and floorsXPS is unbeatable in areas with direct contact with the ground. EPS can be used on interior floors over slabs, provided they do not bear excessive loads.
- Interior walls and ceilingsFor maximum noise reduction and moisture control, rock wool (or mineral wool in general) is still the winning choice.
Before deciding, identify where your home loses the most heat (you can request a free professional diagnosis from many companies)..
Regulatory and normative aspects
In addition to technical analysis, you must comply with regulations. In Spain, the Technical Building Code (CTE) and UNE-EN regulations specify the requirements for thermal insulation, fire performance and product characteristics.:You can find more details here.
- UNE-EN 13163 and 13164 standards: EPS and XPS must have CE marking, guaranteeing their quality and performance.
- Euroclasses for reaction to fire (UNE-EN 13501-1): The B-s3,d0 classification for XPS and EPS, and A1 for rock wool, mark the level of fire safety.
- Public aid and subsidies For energy rehabilitation, materials that maintain their properties over the long term and certification guarantees are usually required.
Don't forget that, in addition to choosing the best material, Professional installation ensures that the insulation performs at its best and complies with current regulations.Poor assembly can negate all the advantages of even the most expensive or advanced product.
What is the best insulator for each need?
There is no such thing as a “universal perfect material,” but there are better options depending on your situation:
- If you are looking for resistance and maximum durability against humidity or compression: Choose XPS.
- If you prioritize costs and ease of installation for renovations or rehabilitation: EPS is your solution.
- If you need sound insulation, fire safety and maximum durability: Invest in rock wool.
For humid climates, rock wool helps the home breathe and prevents mold. In areas with frequent rainfall and a risk of condensation, XPS or EPS (in waterproof systems) are very effective. And if you're also concerned about your environmental footprint, rock wool and other natural materials (cork, cellulose) offer sustainable alternatives.
It's essential to analyze the technical properties of each material, your local climate, your budget, and regulatory requirements to choose the most appropriate option. Each material has its ideal application. If you make the right choice and installation, you will have a more comfortable, efficient and sustainable home for years to come., improving quality of life and saving on energy bills from day one.
