Grade three insulation what does it really mean?

When a motorhome or caravan is constructed, the manufacturer will give a great deal of thought to insulation. With this in mind, some units are classed as having grade three insulation. Others are insulation grade two. So what exactly is meant by the term grade three insulation?

A motorhome or caravan that is constructed with insulation grade three should be able to maintain an interior temperature of +20 degrees centigrade internally, with the heating system on, when the outside temperature is -15 degrees centigrade. It is as simple as that. This is not a reference to “winterisation” or a “winterised unit”. That is a different thing altogether.

Grade three insulation

Grade three insulation is a Kon-tiki feature.

My present motorhome, the Swift Kontiki 679 is a model with insulation grade three. During the winter of 2010-2011, outside temperatures were -18 degrees centigrade but inside was warm and snug. It was also way over twenty degrees centigrade.

Of course, if you throw enough energy at something, then any temperature inside should be achievable. For example a glass greenhouse could probably be maintained at twenty degrees centigrade when it is -15 outside. However, tremendous amounts of heat energy is likely to be needed.

Grade three insulation vs grade two?

On a similar theme, a motorhome or caravan that is constructed with insulation grade two should be able to maintain an internal temperature of +20 degrees centigrade when the outside temperature in zero degrees centigrade.

A motorhome that is fully winterised generally has all plumbing, (ie fresh water tank, waste water tank, drain pipes and fresh water pipes) located in a twin floor. The space between the twin floor usually has a heat source too. It is possible that you could buy a motorhome or caravan with insulation grade three only to find that the fresh water tank is underslung and therefore possibly at risk of freezing in the wintertime. So, in reality, the motorhome or caravan would be warm and snug internally, but the water tank could be frozen solid. The point here being that the insulation grade of the unit is not the same as being “winterised”.

Some buyers may however find the insulation grade useful when considering a vehicle for all year round use.

The Kon-tiki is a British built motorhome, manufactured by Swift. This link to the Swift website will explain a little more about the concept of grade three insulation.




  1. Craig Gadd September 23, 2017
    • Motorhome Voyager October 13, 2017

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