Special
Sorts of hygrometers
MEASURING MEANS KNOWING WHICH WOOD MOISTURE METER IS MOST SUITABLE IN EACH SITUATION? Before you start fitting a wooden floor, you obviously need to know how much damp is present, since damp is the biggest enemy of this natural material. This means you measure to make sure that the subfloor (the base for the top floor) is dry enough and that the wood itself meets all the requirements for ideal fitting. After all, the last thing you want is a floor which curls, shrinks, or cracks. You measure the damp in the wood to establish various matters. Considering the type of subfloor is a logical start. Every subfloor has its own properties, so it’s important to know how much damp is acceptable and at what point do all the alarm bells start to ring.
Types of subfloors It seems best to us to consider a few common subfloors and give a handy list of the various limits: - sand-cement covering floor/concrete floor with no floor heating < 2.0CM% - sand-cement covering floor/concrete floor with floor heating: < 1.8CM% - anhydrite covering floor with no floor heating: < 0.5CM% - anhydrite covering floor with floor heating: < 0.3CM% - wooden subfloor: 9-11%. Remember that, generally speaking, you should not glue a floor or apply a levelling agent if the figures are above those percentages. In all this you have to consider residual moisture and a potentially structural damp problem. We speak of residual moisture when a new covering floor in sand-cement or anhydrite is fitted and then dries out and sheds moisture. If there is a structural damp problem caused, for instance, by a leaking pipe, then obviously structural repairs will be necessary first, but we’re not considering that issue any further here.
Measuring wooden floorboards When we speak of measuring wood moisture, we think almost automatically not of the subfloor, but the material itself. That’s not surprising. We all know that wood is a live material which you have to approach in the right way. If it is too damp or, by contrast, too dry, you can expect problems later with open joints, curling, cracking, shrinking, etc. Moreover, we sometimes forget how important it is to fit a wooden floor at the right temperature.
Two types of moisture meters There are lots of devices on the market, but, generally speaking, you have to be aware that there are two ways of measuring, namely destructive and non-destructive. With the former, you literally measure a lightly or severely damaged part of the covering floor or wooden floor
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by driving pens into the wood. With the non-destructive method, you hold a measuring head to the material. And so, the choice of type of meter depends on your intention and whether or not you can permit any damage. With the destructive method, you will most commonly hear professionals talk about the so called ‘carbide method’. With this method you take a sample from the covering floor to force any moisture present to react with carbide so that you can measure the residual moisture content. A CM moisture meter measures the gas pressure which is created by a reaction from the moisture in the covering floor material to the carbide in the moisture meter. You collect the material from the lowest zone of the covering floor, so you have to make a hole in the covering floor and fill it in later. Non-destructive devices are tools which are sometimes called capacitive moisture measures. They operate on the principle that you drive an electric current through the wood and then compare the result with the values of the relevant wood sort. And so, this device is simply put onto the material itself and monitors the density of the raw material.
A hygrometer isn’t a luxury As we’ve said above, you have to measure more than just the damp in the covering floor or the wood itself. Good fitting is not complete without an accurate idea of the air humidity and temperature. To do this you use a hygrometer. The ideal feature of such a tool is that it is multifunctional, so it can measure several factors.
One specialist Brookhuis Applied Data Intelligence Brookhuis Applied Data Intelligence is a leading producer of solid wood and building moisture meters, In-line moisture meters for solid wood, handheld and In-line measurement systems to determine the strength of timber and finally, the ICD scanner, which is detecting In-line checks, cracks, splits and open glue-voids in, for example, flooring components. In the product range, Brookhuis is having 5 hand-held moisture meters. 2 of these are so called capacitive moisture meters (FMW-B and FMW-T) that can measure the moisture content of solid wood and subfloors without damaging the material. The 3 other hand-meters are so called resistance type moisture meters (FMC-FME and FMD6) that can measure the moisture content of solid wood and subfloors by using a probe that is fitted with measuring electrodes. The capacitive handheld moisture meters are mainly used for QC (quality control) tasks due to their ease of use and speed of measuring
