Facade insulation – Mineral insulation materials at a glance

There are various options for facade insulation as well as insulation under the roof, in and on interior walls, floors, the basement and more.

Thermal insulation aims to prevent cold and heat from the outside from penetrating and thermal energy from the inside from escaping too quickly. Natural solutions for this are mineral insulation materials.

The different types of glass wool and rock wool, expanded clay and mineral insulation, silicate insulation and perlite pellets offer different advantages and disadvantages.

What are mineral insulation materials?

The term minerals almost brings together different, naturally occurring as well as inorganic substances; for example lime, sand and various rocks.

The good thing about this type of raw material is that they are abundant and do not have to be produced artificially. In addition, they cannot rot and some are, with breathable insulation, good buffers for humidity.

Cleanly processed and installed or treated in advance, they offer hardly any possibilities for mould growth. Different mineral insulation materials made from minerals have different advantages and disadvantages. The following is an overview.

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Overview of mineral insulation materials

Glass wool

Glass wool as insulation is probably best known. The mostly orange-yellow mats consist of waste glass, quartz sand and limestone.

glass wool insulation facade

The first two components give the mineral insulation material its name. Glass wool is often used as roof insulation as well as for facade insulation behind the curtain wall. It is important that it should be installed protected from moisture and dampness, as it can easily soak up water.

Besides glass wool as mats, the insulation is also available as blow-in insulation. Protective clothing is recommended during processing, as fibres that come loose can cause skin irritation.

– Good thermal insulation of glass wool – Good protection against vermin, mould and rot – Fire protection, as the material does not burn – Flexible use; can be cut to size or blown in– fibres may irritate skin, eyes and mucous membranes – Must be processed with protection against moisture / wetness – No resistance to pressure (good for transport, but must be considered during installation) – Production of glass wool is energy-intensive

Rock wool

Rock wool as insulation is very similar to its glass counterpart. Different types of stone can be used in the production process, waste glass is not a component.

rock wool insulation facade

The properties and instructions for processing are also the same – rock wool can soak up water, which is why it should be used protected from moisture and damp. Fibres can also come loose, which can cause skin irritation. Protective clothing is therefore necessary when handling the mineral insulation material.

For this purpose, there is also a good insulating effect and fire protection, as the processed rock is not combustible. One difference: rock wool can withstand more pressure.

– Good thermal insulation of rock wool – Good protection against vermin, mould and rot – Fire protection, as the material does not burn – Flexible use; can be cut to size or blown in– fibres may irritate skin, eyes and mucous membranes – Must be processed with protection against moisture / wetness – Production of rock wool is energy-intensive

Foam glass

Foamed glass as an insulating material has waste glass as its starting material and is therefore an important mineral insulating material in the recycling sector.

spray foam insulation facade

Unlike its two predecessors, foam glass offers high resistance to moisture, so that it can be used throughout the house. Roof, upper floors, ground floor, cellar, garage and more can be thermally insulated with it.

The pressure-resistant material is available as sheets, granules or pellets and as moulded parts. But the price is higher than the previous two.

– Good thermal insulation through cellular glass – Resistant to pests and acids – Fire protection, as the material does not burn – Resistance to pressure, water and rotting– Comparatively high price for this mineral insulation material – Production of foam glass is energy-intensive


Perlite refers to a granulate which also has the long-lasting properties of other mineral insulation materials: it does not rot and is not combustible.

In addition to the frequently used granulate form, which is suitable for blow-in insulation between two layers of masonry, perlite boards are currently also being used for thermal insulation.

Perlite is the preferred choice when both thermal and sound insulation is required. However, the thermal conductivity of volcanic rock is only in the medium value range.

– Unattractive for pests / insects – Fire protection, as the material does not burn – Sound insulation is good– Only medium thermal insulation through perlite

Silicate / calcium silicate

Silicate and especially calcium silicate offers the buffering capacity against moisture mentioned at the beginning. During installation, a vapour barrier is not necessary to retain humidity.

silacate insulation

This advantage is unfortunately outweighed by a decisive disadvantage: the insulating properties of the mineral material are in the lower range. It is therefore necessary to consider the type of property in which calcium silicate is to be used – it is always flexible so that it can be used in roofs, ceilings, walls and floors.

All in all, it is recommended primarily for interior insulation, less so for facade insulation. The silicate can be used both as panels and as fill.

– Fire protection, as the material does not burn – Breathable against moisture– Only low thermal insulation through calcium silicate

Mineral insulation

Mineral insulation or mineral foam can be somewhat misleading as a designation, as the above-mentioned products are of course also made of minerals.

The insulation material known as “mineral insulation” is composed of cement, lime, sand, gypsum and aluminium; when produced with water, hydrogen escapes, which leads to the formation of pores. The resulting foam is processed into boards.

The breathable material is mostly used for interior insulation, less frequently as facade insulation (but then applied inside).

– Fire protection, as the material does not burn – Breathable against moisture – Good for insulation inside the house (wall, basement ceiling, screed insulation, flat roof, etc.)– Not intended for facade insulation

Expanded clay

Expanded clay as insulation is a very interesting possibility to realize thermal insulation.

extended clay insulation facade

Although the thermal insulation property is only in the middle range, the protection against heat in summer is comparatively high. Added to this is good sound insulation.

Expanded clay granulate applied to flat roofs is also often used for greening in addition to insulation. The production process consists mainly of heating naturally occurring clay to 1,200°C, which causes trapped organic substances to become gaseous and spread; the clay is expanded.

extended clay facade for insultation

The granulate can be used as loose insulation; in combination with lime and cement as insulating lightweight concrete panels.

– Fire protection, as the material does not burn – Heat protection in summer – Flexible use as bulk material – Can be used as panels in the form of lightweight concrete– Only medium thermal insulation properties for expanded clay
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