Insulating a boat with Froth-Pak

Boot isolatie

Condensation on the boat hull can lead to mold. But how can you avoid condensation on the metal? This can be done by spraying a fine layer of PUR foam against the metal. This ensures that condensation will no longer occur. If you really want to insulate the boat, you have to make the spray layer thicker. Because Froth-Pak is a closed-cell foam, moisture cannot be absorbed into the foam. The foam and the hull form a hermetically sealed part.


In this article you can read how to insulate a boat with Froth-Pak PU foam to prevent condensation on metal.

Tip: want to know more about Froth-Pak PU foam? Then read our information article “Using Froth-Pak Pu foam | Tips & Tricks”.

Does PUR absorb moisture?

It is important to know that there are two types of PUR foam. Open cell and closed cell. With an open-cell PUR system, moisture can be absorbed into the foam, so we want to avoid this. That is why it is better to choose closed-cell foam such as Froth-Pak when insulating a boat hull. As the name closed-cell indicates, this insulation foam is chemically composed of millions of individually sealed cells that cannot contain moisture.

Boat hull preparation

When applying PUR foam, it is important that the boat hull is dry and free of grease. We recommend this to ensure perfect adhesion. While the PUR foams from the hardware store usually need moisture to get the chemical reaction going, this is the other way around with Froth-Pak. A dry surface is therefore very important. You can simply dry the surface with a cloth or by warming the interior of the boat with a heating stove. There is a second point of attention, namely that the interior space and the surface to be sprayed must be above 5°C. This way you get perfect adhesion.

Benefits of Froth-Pak

Froth-Pak PUR foam has a density of ± 30 kg/m3, making it a very light foam. In addition, Froth-Pak foam is very flexible. This means that the foam, after application, also moves with the metal of the boat hull. There is no risk of Froth-Pak foam cracking or cracking due to torsion on the ship, regardless of the thickness of the foam layer.

What materials do you need for your insulation job?

Before you start, it is important to know how much volume of foam you need. You can do this by multiplying the number of square meters by the desired thickness. An example: for an area of 20 m², where you want to spray a thickness of 5 cm, you need 1 cubic meter of foam (20 x 0.05 = 1). For this application you would need the following materials:


With condensation, a layer of 2-3 cm is sufficient to completely cover the metal. If you wish to insulate, a thicker layer must be sprayed. You apply a thickness of 8 cm, for example, in 2 separate layers, with the first layer having hardened after five minutes. As soon as you can touch the foam without it still sticking to your gloves, the next layer can be applied.

Recommended protective equipment:

Tip: if you order the PU safety package you will have all the necessary protective equipment at home.

More information about insulating with Froth-Pak?

Do you have questions about Froth-Pak or about insulating your boat? Please feel free to contact our customer service, we will be happy to help you!

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