Heat losses are – next to moisture – the biggest enemy of residential buildings. Especially in the case of energy-efficient houses and those that meet the criteria of passive construction, adequate thermal insulation is essential. Not only is it important to execute the insulation works accurately, but also to choose the right system. A technology that has gained importance in recent years is spray insulation using polyurethane foam.
Polyurethane, known as PUR foam, is a high-class polymer obtained by combining polyol with isocyanate. Polyurethane foam is produced directly on the construction site thanks to the use of special foaming machines. Due to their variable parameters, polyurethane systems are available in many versions, which makes PUR foam a universal thermal insulation material for all surfaces.
The polyurethane foams available on the market can be divided into open-cell and closed-cell foams. Open-cell foam is characterized by high thermal performance, and has the structure of a light, vapour-permeable sponge. It works as an alternative to mineral wool, while additionally being elastic, which makes it an excellent material for insulating structures and materials that may change shape over time – e.g. wood.
In turn, closed-cell polyurethane foams are recommended as an insulation material for places particularly exposed to moisture, because they offer high water resistance. They have a structure of microscopic, closed bubbles, which provides it with similar properties to those of XPS polystyrene. The excellent thermal insulation parameters combined with the lightness of the material make the closed-cell PUR foam perfect for external thermal insulation.
Now that we are familiar with polyurethane foam and its applications, it is worth discussing the most important advantages of choosing this insulation system. There are well over 5, but the following ones certainly deserve special attention.
Increasing energy efficiency may apply not only to buildings that do not have any thermal insulation, but also to ones that have already been insulated. Due to its lightness and excellent adhesion, PUR foam is often used to provide an additional layer of insulation applied onto the old system, e.g. polystyrene. Due to the fact that polyurethane undergoes intense expansion, it is also perfect for thermal insulation of three-layer walls, precisely filling all gaps and preventing the formation of thermal bridges.
Both mineral wool and polyurethane foam are materials with a high degree of vapour permeability. However, the advantage of PUR foam over wool comes from the fact that it does not absorb water, so it is much more resistant to moisture. For this reason, the polyurethane system makes an unfriendly environment for all kinds of fungi, mould and other microorganisms that affect the quality of thermal insulation, the condition of building materials as well as our health and comfort of life.
The effectiveness of polyurethane foam also stems from the fact that you can use it to insulate virtually any surface. Concrete, wood, metal, sheet metal, polystyrene – polyurethane foam perfectly sticks to each of these materials. Thanks to its properties, it is the most effective thermal insulation system for attics and attic slopes. It tightly and thoroughly penetrates all nooks and crannies – also where the correct application of polystyrene or wool is not possible.
Choosing a polyurethane system instead of traditional insulation materials also saves a lot of time. For example, a qualified team of workers is able to insulate a 1000 m2 roof in one day.
The structure of PUR foam as a thermal insulator makes a much thinner layer enough to provide the appropriate thermal parameters compared to other materials. This advantage will be appreciated by attic owners, where one of the basic problems is limited usable space.
While the thermal conductivity for wool is 0.044 – 0.034, and slightly below 0.040 for polystyrene, in the case of PUR foam it may be as low as 0.022. This means that polyurethane is the most effective thermal insulator among all systems available on the market. Thermal insulation with the use of polyurethane is completely safe, both for people and animals, as well as the natural environment. PUR foam does not cause allergic reactions and does not raise dust. At the same time, it creates an unattractive environment for insects, rodents or other pests, and its durability is estimated at up to 50 years.