How to inject polyurethane foam into the wall?

It is simple to effectively inject polyurethane foam into the wall, but it does require knowledge of the climatic conditions and the manufacturer's requirements.

Injected polyurethane is a polyurethane foam insulation system, which is obtained by mixing polyol and isocyanate in a tank. The resulting material is then injected into a cavity, where it expands, adapting to all irregularities and forming a rigid and highly durable insulator. In this way, cracks, holes and joints are filled, preventing any infiltration of air or water. Therefore, the injected polyurethane is by design hermeticity sealing, which is fundamental for the energy efficiency of the buildings.


How to inject polyurethane foam into the wall?


The injected polyurethane, with the minimum thickness, achieves a very effective insulation, as it has a thermal conductivity eight times lower than the air chamber it fills. It is also an excellent acoustic absorbent, waterproofing agent, and its installation does not reduce living space. In addition to these advantages of injected polyurethane, it should be noted that its installation hardly causes any inconvenience to the users of the building. 


Types of facades or partitions where it is advisable to inject polyurethane

Regarding the insulation of facades with an air chamber, injected polyurethane is particularly suitable when there is no option to intervene from the outside. Also, due to its great adhesion it can be applied to all types of surfaces, vertical or horizontal, interior or exterior, and to very different materials.

It is also highly recommended for application in areas that are not very accessible. All of this makes it the most appropriate option in energy rehabilitation projects. 

The injected polyurethane also manages to repair and stabilise the walls, as its expansion solves any cracks or fissures that may have appeared over the years. It is also effective in insulating flat or sloping roofs, as well as ceilings, either from the inside or from the outside. The advantage is that it does not add weight to the structure, it consolidates the floor and it does not have any danger of detachment. 


Polyurethane applications for building - Infographic


Climatic conditions for injecting polyurethane

In order to know how to inject polyurethane foam into the wall correctly, it is first necessary to know the appropriate humidity and temperature conditions for the application.

The minimum temperature of the substrate will be 5º, the same as the ambient temperature, which will never exceed 40º. It is recommended that the ambient humidity be less than 85%. In the case of a porous substrate, the requirement will be reduced to 20%. If it is not porous, it must be completely dry. 


How to inject polyurethane foam into the wall?


Step by step of polyurethane injection

To begin with, it is necessary to check for defects in the substrate, cracks or moisture. If this is the case, a solution must be applied before starting the injection. It is also necessary to detect the existence of electrical or water networks, as well as to seal plugs and connection holes. 

So how do you inject polyurethane foam into the wall? Installation is simple. The polyurethane injections must be made through in-line holes, with a separation between them of between 50 and 150 cm. Start at the bottom of the chamber and work your way up. 

It is essential that the task is carried out by a professional who has the necessary machinery, who knows the application conditions and the manufacturer's requirements. 


Polyurethane applications for building - Infographic



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