Measure Moisture in Caravans and Motorhomes

How to measure moisture within caravans and motorhomes is a common question which we receive all year round. After all, the purchase of a caravan is an investment for future holidays and owners want to keep them in their best condition.

Like a home, atmospheric moisture levels will increase in line with exterior moisture levels, too high and condensation occurs. Faulty seals and broken exterior shells will allow moisture to enter.

A caravans and motor homes are manufactured from a range of materials, including wood, foam and fabric which can absorb moisture. Where moisture enters the caravan through the exterior fabric, internal components will become damp, especially wood and fabrics, this is material based moisture. When moisture levels in the air reach to high, the water molecules will appear as condensation on cold surfaces, which in turn is absorbed by materials, this is airborne based moisture.

Some materials will be covered with a coating providing a durable surface and an enhance quality finish (cupboards and doors). If high moisture levels are present, the underlying materials like wood can absorb water molecules, but due to the exterior finish, the owner will be unaware of water damage until the coating peels off.

In fact, the only time an owner may be aware of potential moisture issues, is when the level is too high, causing damage to internal components. If you can see or feel moisture, then it’s too high!

Electronic moisture detectors can ‘detect’ moisture levels at a lower level than with touch and sight. The earlier moisture is detected, the easier it is to rectify. So it is prudent to check moisture levels with an electronic device.


Two Types of Moisture
As mentioned, there are two types of moisture, airborne and material based.

Airborne is the moisture contained within the air. This should not create a problem in normal conditions, but can lead to condensation, rot and corrosion especially if combined with low temperatures.

Material based moisture has been caused by water travelling from one material to another. Faulty seals or damage to the external structure is a common cause, along with damaged pipes under sinks or around the shower.


Measure the air humidity
Moisture in air is measured using Relative Humidity (RH). Below 75% RH is classed as dry, whilst anything over 75% RH will allow bacterial and fungal growth.

Electronic hygrometers like the Protimeter Hygromaster will provide an accurate reading of the humidity in air. Utilised by surveyors, both instruments record the measurements using %RH with temperature readings.

A simple method to test the air humidity within the caravan is to use a chemical reaction. Fugenex Damp Protect is a simple card incorporating a strip of paper which reacts to airborne moisture.


Moisture in the Caravan material and structure
There are two types of moisture meters than can detect and record the levels of damp within the caravan. The first instrument utilises two metal pins which provides a direct reading and the second instrument utilises a non-invasive radio mode.

Two-Pin Devices
A moisture meter featuring two metal pins at the top of the instrument will record the level of moisture by measuring the resistance between the pins. It is a direct reading and provides the best accuracy. Several models are available, Protimeter Mini and Protimeter Digital Mini.

However, most of the interior and exterior of the caravan contains surfaces that do not directly hold moisture, but provide a protective finish. The pins would therefore be required to push through the finished surface into the layer below.

This would leave a mark and is only advised to undertake from inside the unit and on surfaces that will not be directly seen by any future buyers.

Non Invasive Radio Mode
This method utilises moisture detection which sends a signal below the surface of the material to a nominal depth of 19mm. The instruments will not damage the surface so is ideal for all interior and exterior applications. The Protimeter Aquant2 features non-invasive moisture detection.

A major material found within a caravan is aluminium and steel which provides strength. All metals provide an excellent conductive material, so don’t be surprised if you receive a high signal around the metal structure.



Recommended Models
We would always recommend the Protimeter range due to their high standard of manufacture, outstanding performance and onsite durability. Plus they feature a two year warranty!

For direct readings, we would recommend the Protimeter Mini as it is the simplest instrument.

For a combination of two-pins and non-invasive we would recommend the Protimeter Surveymaster.

For air humidity readings, we would recommend the Protimeter Hygromaster which allows the user to interchange the sensor.

If you are employed by a caravan specialist, you may be best to purchase the Protimeter MMS2 which incorporates all functions into a single unit.


Further reading
Digital Moisture Meters
Dealing with damp in a caravan
Camping and Caravanning Club - Winter Caravan Checks

How To Detect Moisture In A Building

Detecting moisture in buildings is relatively simple with the right instrument and following the correct procedure.

There are multiple reasons why moisture can enter a building structure, but for the purpose of this article we will look at how to detect moisture using electronic equipment.

But what is moisture?
Moisture can be found throughout the building structure in differing levels and can fluctuate throughout the year. For most of the time, this will be minor atmospheric moisture absorbed by the building material or covering (wall paper and flooring).

However, moisture is a hazard long before you see it and will not become visibly damp until it is too late. Degradation of the material will start before it can be detected with human senses like touch.

Building materials are like sponges, featuring a porous structure which absorbs water. If water enters a property, it can travel for the primary source to a secondary material. This ‘diffusion’ drives the mositure to dry areas and eventually the surface where you would normally encounter a problem.

Surface moisture can dry through evaporation caused by air movement. But in most cases the surface has a covering (wall paper, paint or wood flooring) which acts as a barrier stopping evaporation. Initially you will not encounter a problem until the moisture level reaches a point that causes the covering to lift, peel or crack.
When undertaking an inspection of a property, a good surveyor should check both the surface and sub-surface moisture levels. This will ensure that any potential problems are spotted before it’s too late.

How to detect moisture
When undertaking a moisture reading of a building structure, there are three test that can be performed; surface moisture reading, sub-surface moisture reading and humidity.

Protimeter Mini taking a reading with pins

1. Surface Moisture Readings
Measuring the surface moisture is a relatively simple process utilising a pin type electronic moisture reading device.

Both the Protimeter Mini and Protimeter Surveymaster incorporate two metal pins at the top of the instrument. By placing these pins on the surface, the instrument reads the moisture levels between the pins. Higher the water level will generate a higher moisture reading.

The readings are displayed through a simple coloured LEDs. Green for good, yellow for borderline and red for bad. So simply, if the reading is in the green the moisture level is at a 'no risk' level.

If the reading displays a yellow LED, the surveyor should determine if further inspection of the building structure should be undertaken. If the reading is in the red, the moisture level is too high and the surveyor should undertake a further assessment.

With the Protimeter Surveymaster, the readings are supported with a LCD display providing a digital reading of the moisture level.


2. Sub-surface Moisture Readings
Sub surface readings are an important indication of the moisture condition of the building structure. More moisture will be locked inside the building material than on the surface.

Protmeter Surveymaster using the search mode

Non-invasive
Protimeter has developed a non-invasive search mode which penetrates to a depth of 20mm. The return signal will be displayed digitally through a simple LCD display between 0 to 1000 REL. The REL stands for relative reading and is an indication of the moisture level.

Again a simple LED display employed to provide a quick determination of the reading. If the moisture level is too high, a further invasive test should be undertaken.

Both the Protimeter Aquant and Protimeter Surveymaster are equipment with this method of moisture detection.

Protimeter Mini using deep wall probes for electrical conductivity test

Electrical Conductivity
One further method for measuring sub-surface moisture is to drill two holes and pass a deep wall probe into the wall. The moisture readings are measured by the electrical conductivity through the material. Higher the reading the larger amount of water is present. This provides an important additional check to determine the extent of moisture in a material like a wall or concrete structure.

This can be undertaken with the Protimeter Mini, Protimeter Surveymaster and Protimeter MMS2 models.

Protimeter MMS undertaking a humidity and condensation test

3. Humidity Test
Commonly within a property a high level of humidity will be generated through general living conditions. Either through cooking, taking a shower or even breathing, moisture will be released into the environment.

Without proper air circulation, the first thing you may see is condensation on windows or tiles. In server conditions, wall paper will start to peel off and mould will grow.

By utilising a Protimeter Hygromaster, Protimeter Pysclone or Protmeter MMS2, the surveyor will be able to take a digital reading of the humidity levels.

All readings are displayed as a %RH (Relative Humidity) supported with either a temperature reading or dew point reading.

If the reading is above 70%RH, the moisture levels within the environment are high enough for bacteria to grow. It’s the bacteria that breaks down the building materials and causes damage.

With the Protimeter MMS2, a condensation test can be performed. This runs through the relevant moisture and temperature readings to determine if there is a condensation issue.


Further Reading

If you would like more information on moisture
Dampness Measurement in Concrete Floors
How to Measure Moisture in Buildings


If you would like more information on the Protimeter range, please visit www.damp-meter-direct.co.uk
Protimeter Mini
Protimeter Aquant
Protimeter Surveymaster
Protimeter Hygomaster
Protimeter Pysclone
Protimeter MMS2

Protimeter Moisture Meters

Protimeter is a premium range of professional moisture measuring instruments for surveyors, flooring contractors and assessors alike.

Originally from Marlow in Buckinghamshire, Protimeter has been at the forefront of moisture meter design for over 40 years and has developed many of the technologies that are central to moisture measurement and dampness diagnosis within the built environment.

In 2001 Protimeter was acquired by the General Electric Company and became part of what is now the GE Measurement and Control business. This is a business that “sets best practice today and constantly explores solutions for tomorrow, all in an effort to keep their customers at the front edge of quality, safety, service and productivity”.

Protimeter = Higher Quality
Protimeter instruments are designed for professional use. They last longer, function better and provide a higher level of measuring confidence than many other products that are available. With a 2-year warranty the instruments are the best choice for demanding moisture measurement applications.

‘I have been involved with Protimeter for many years, and commonly customers comment on the superior quality of these instruments.’ comments Ian Guest, Marketing Manager, Survey Express Services. ‘We have found no other range of moisture meters that operate better than Protimeter and that last as long.’

Protimeter Range
Protimeter produce a range of devices that includes the simple Salts Analysis Test Kit, electronic moisture meters and hygrometer and the highly specialised Speedy Moisture Tester.

The entry level moisture meter is the Protimeter Mini, with two pin-electrodes and a colour coded LED scale. The Protimeter Aquant is a moisture detector that transmits radio waves for sub-surface moisture detection, without the need for drilling into the surface. The Protimeter Surveymaster combines the functionality of the Mini and Aquant into one instrument, enabling the user to distinguish surface from sub-surface moisture levels.

Environmental humidity and temperature levels can be measured by the Protimeter Hygromaster and Protimeter Pysclone thermohygrometers. Both instruments also calculate the prevailing dewpoint temperature, and both can be used with a surface temperature sensor for condensation risk assessment applications.

The Protimeter MMS (Moisture Measuring System) combines the functionality of the Mini moisture meter, the Aquant moisture detector and the Hygromaster into one multi-functional moisture measurement tool. The MMS is the logical choice for professionals that need to fully understand the moisture levels of the building itself and of the environment within the building.

The Protimeter Timbermaster is optimised for measuring moisture levels in wood specifically. It has eight user selectable calibration groups that enable more precise measurement in over 150 different wood species. When necessary, the Timbermaster can also be used with a temperature probe for temperature correction and with a Hammer Electrode for sub-surface measurement.

The Salts Analysis Test Kit is used to assess relative levels of nitrates and chlorides on site when investigating the cause of dampness problems. High levels of hygroscopic salts contamination can affect moisture meter readings, so it is often necessary to test for their presence when diagnosing dampness problems in buildings. Additionally, high salts contamination can indicate problems associated with rising dampness, as they are present in ground water.

The Speedy Moisture Tester measures the moisture content of a sample of building material by chemical reaction in a vessel. It complements moisture meters and hygrometers, and is often used to measure material that may have been contaminated by conductors such as hygroscopic salts.

For more information on the Protimeter range visit our website www.damp-meter-direct.co.uk