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Moisture ingress

What to look out for with regard to water ingress in Caravans and Motorhomes

The products used to build the interior and core panels of the vehicle will have a big influence on the outcome of water ingress to the vehicle.

For this article, we will categorize the vehicle construction methods into two main types: absorbent and non-absorbent

Absorbent structures

The early model vehicles were built with an imperious Alloy or Fiberglass outer core and an absorbent Polystyrene foam inner core plus an absorbent decorative plywood inner liner; these vehicles will deteriorate very quickly once any water gets in through a seam, roof vent, or window frame or access door.


The materials used were lightweight, and therefore, they deteriorate rapidly once wet; the structural areas around the window and door frames or wall and floor perimeters and frame struts were made of lightweight untreated timber.

It only takes a couple of months of high moisture levels in the walls to cause irreversible damage to the structure, and it is expensive to repair   

Non-absorbent structures

The newer vehicles are being built with non-absorbent materials, which greatly reduces the impact of moisture ingress to the vehicle interior; the products used now are closed cell foam insulation sandwiched with fiberglass inner and outer skins; in some cases, the outer skin is powder coated Aluminium.

If water penetrates this type of construction, the inner lining and foam are not affected by the water because it is impervious, but the interior furniture and fabrics could be compromised.

Why water gets into your vehicle

The water will mostly enter due to poor maintenance. Motorhomes and caravans are always on the move, under the impact of vibrations from road surfaces. Most manufacturers will give a 5-year water ingress warranty, but only if the vehicle is inspected by an approved motor home or caravan agent.  After the five-year period is over, most owners don't bother having any more inspections done, which does not make sense, because that is when the seams, wall-to-roof connections, skylights, and window connections might start working loose, and because the vehicle is no longer under warranty the repair costs are now for the owner to bare.

How to prevent water penetration

There are a couple of things you should do:

  1. Always ensure that the annual inspections are maintained religiously and that any issues picked up in the report are fixed as a general maintenance plan; the cost of maintenance is much less than the cost of repairs
  2. Store the vehicle in a sheltered location, under a canvas cover or shed. The canvas covers will sometimes cause scuffing to the paintwork and acrylic windows; you can avoid that from happening if you mask those areas with bubble wrap or something similar

Images of ingress problems


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