First of all, let’s start by clearing something up, to ostensibly when people refer to ‘Moisture Meters’ or ‘Damp Meters’ they are referring to the same thing. Professionals tend to use the term moisture meter as they do more than measure damp, which people most often associate with rising damp or penetrating damp.
You can find out more about rising damp and penetrating damp in our article about damp walls. However, in this article, we will look at a range of many different types of moisture meters and explain how they work differently on different materials, plus the different moisture meter readings you can get from them.
Moisture meters and damp meters can make excellent leak detectors.
There are many different manufacturers of moisture meter in the UK, but for the purposes of this article, we will use examples from two of the most well established professional moisture meter companies – Tramex Moisture Meters (established in 1974 and based in County Wicklow in Ireland) who have a range of meters for various purposes and also Protimeter Moisture Meters (formerly owned by GE but not part of Amphenol Advanced Sensors)
How is a Moisture Meter Used?
As we mentioned earlier, there are a range of different moisture meters with various applications, plus there are certain types of moisture meter which have different uses / measurements they take. So clearly, how you use a moisture meter will depend on what you are testing and the model you are using.
To help keep this fairly simple, and easy to understand, in this article we will firstly differentiate between pinned moisture meters and pinless moisture meters (of which there are many).
When people think of moisture meters, they commonly think of pinned meters like those shown in the image below, where two or more pins are pushed into a material such as wood, plaster, render or even concrete leaks (which is obviously difficult – more on that later) and a reading is given.
However, as well as pinned and pinless meters, there is another group which we will label as ‘hygrometers’ which measure relative humidity (and other metrics) in the air rather than materials. Le’ts now look at those one by one. Before that, we have a useful guide to reducing humidity, you will find useful.
Pinned Moisture Meters
As we said earlier, pinned moisture meters are perhaps the most well known types of meter to measure moisture and damp in materials. Taking a look at the Protimeter MMS2 below, you can see the right hand image using it as a wood moisture meter and top left measuring moisture in plaster.
As you can see in each of those readings, both are measuring Moisture Content Percentage (MC%). Perhaps the simplest way to explain this would be to say that, for a reading of 100% the material is holding as much water moisture as it can, 100% is effectively saying the wood or plaster is saturated with water.
Pinned moisture meters work by passing an electrical current or signal across the pins and measuring the resistance (hence why they are sometimes known as resistance meters), knowing the variances correlates with different amounts of moisture in the material which is shown on the meter display, digital or analogue.
When the material is not wood, then a Wood Moisture Equivalent (WME) reading is given. This basically means what the moisture would be as if it were (i.e. equivalent to) wood materials.
Pinless Moisture Meters
We have explained pinned moisture meters, so let’s look at pinless now. As you can see from the images above (showing the Tramex CME5 on the left and MRH3 Meter – bottom right) pinless moisture meters work differently and are less invasive, after all pins do a very small amount of damage to the material. However, pinless moisture meters are non-invasive moisture meters.
Pinless moisture meters commonly work on an impedance measurement process, this is shown in the image on the top right above. Basically, signals are passed across the pads or retractable pins on the meter base through a few centimetres of the material and the readings are translated into a moisture content reading.
These types of meter are especially good for:
- Measuring moisture deeper into solid materials (where putting pins in is harder), including;
- Measuring moisture in concrete or render
- Measuring moisture under laminate floors
- Measuring moisture under tiles in bathrooms or kitchens
- Measuring moisture in masonry materials like bricks
Hygrometer – Humidity Readings (and more)
The third and final group of moisture meters (remembering that some do more than one of these) is hygrometer readings. These take samples of the air, to measure for moisture levels that are present and importantly, measure the temperature too. This is then used to show other useful calculated readings which are relevant.
The different readings that are shown usually include:
- Relative Humidity – this is a measurement of the amount of water vapour in the air. It is expressed as a percentage of what the air is capable of holding at a given temperature. This is why temperature is important as warmer air is capable of holding more moisture. This is why temperature rises, relative humidity falls. This is even if the absolute amount of moisture stays the same, which brings us on to…
- Absolute Humidity – an alternative humidity reading which measures the absolute amount of water vapour in the air. This is usually measured in GPK which stands for Grams (of mositure) Per Kilo (of air). A kilo of air is not far off 1m³ and a gram of water is 1ml.
- Dew Point – dew point is the temperature required for the given readings above, to turn the water vapour moisture back to a liquid. We know this more commonly as condensation. If you think about having a shower in winter, you will see condensation on the cold window but not on warmer surfaces like a radiator. That is because the window is at or below ‘dew point’ to turn the steam back to liquid.
You can read more about the process of condensation, and it’s links to damp and mould in our article about the causes of condensation and mould and in our article about what is condensation?. Plus, both mould and condensation are discussed in our guide to Christmas mould.
Moisture Meter for Leak Detection
Professional moisture meters like he ones we use are a vital tool in the process of carrying out water leak detection in homes and businesses. As you can imagine, as highly sensitive devices they can detect moisture, water and damp in materials even when that is not visible to the naked eye.
Lets imagine you had a bathroom leak and your bathroom was fully tiled. How can you possibly see damp behind or under tiles? Even if you spot an anomaly from another leak detection device such as acoustics or thermal imaging inspections, how do you know if moisture is actually there. This is where moisture meters help to show (a) if moisture is there and (b) an indication of how much.
This also helps to show how a professional leak detection company such as ourselves will not just rely on one tool to find leaks, we use a wide range of professional equipment to maximise the chances of finding any leaks.
Control Readings for Moisture Meters
One last area that it is important to explain is control readings when using moisture meters. Before that, and very much on an associated topic, it is important to remember that all materials used in the fabric of your building (wood, plaster, tiles, bricks, mortar etc) have moisture in them, even if they are considered ‘dry’.
If you had a piece of dry wood and took a moisture meter reading it would not show 0% moisture. Every material has a ‘natural’ level of moisture and it may take on or lose some of that depending on the climatic conditions it is kept in, including the conditions in the house. Of course a water leak can add to moisture levels!
Why is that important? Well if you think about it, lets say you were using a pinned moisture meter and took a reading in some floorboards where you suspected an underground water leak and it said, for example, 15% moisture. You should not immediately assume there is a leak. That may be the normal for that material (knowing that different types of wood vary too) and the general conditions in the house.
This can be helped by taking a control reading in another unaffected area, or even better, a number of areas. This helps to see if that is above the normal control level. Now let’s say you had a reading of 30% and the rest of the house was 15% then that would require further investigation and explanation in the property.
The other useful thing about control readings is that they can help you when doing water damage restoration work as you can use it to help decide if you have dried back to normal conditions for that particular property.
We provide a number of water damage services, we can help you deal with this.
Moisture Meters – Other Useful Information
Here are a few other articles related to this subject that you may find useful to review too:
- Damp Plaster, Concrete & Wood
- Bath Leaking Through Ceiling
- Water Leak in Concrete Floor
- Air Quality Meters
- Air Scrubbers Guide
If you have a water leak contact our friendly and experienced team for help.
Are cheap moisture meters any good?
Although cheap moisture meters can serve a simple purpose, they have limited use and are less likely to be accurate and sensitive. Professional moisture meters are highly sensitive and carefully calibrated for accuracy. Plus, this allows for greater detailed and useful information when diagnosing damp or a water leak. Given the importance of the role they play it is important that we use the best devices possible. We do not use cheap moisture meters nor do we advise you to unless it is for something very simple – for example, people use them to measure fire wood.
Is a moisture meter worth it?
The type of moisture meter we use are professional devices costing many hundreds of pounds (sometimes thousands) and they are an essential tool in many areas of work we do, including leak detection, damp diagnosis and measuring the drying of properties after a water leak or flood. For a general domestic consumer, it is likely that that cost is not practical for very occasional use. Plus, they can be tricky to understand and interpret if you are not trained in using them. If you need help with damp or water leak problems, contact a professional like us.
Is a moisture meter the same as a damp meter?
Generally, yes. Most of the time when people are talking about moisture meters or damp meters, they mean the same thing. Moisture meters, as they tend to be known as in the trade, can be used for a number of purposes including as damp meters but they do much more than that. It’s also important to know that a damp meter should not be the only device used to diagnose damp. The presence of moisture is not necessarily caused by damp, it could be a leak or condensation.
What is moisture mapping?
Moisture mapping is the process of meaning moisture across an area such as a wall, floor or ceiling and comparing readings, typically on a matrix or grid system. Using a moisture meter and logging the readings allows you to compare levels of moisture across an area which can be useful in leak detection and assessing water damage to a property (to see how far moisture has travelled) it can also help see how things are drying too.
At Rainbow Restoration – York & Yorkshire Coast we are experts in Leak Detection, including business water leaks, so if you need help finding a water leak or getting your property back to normal after a water damage or a flood, get in touch with our friendly local team who will be happy to help you with this. We are based in York and help with water leak detection in York.