FCI Floor Installer Magazine article
|Detection is the first step to prevention, here is an inexpensive solution |
If it would not be for mold growth on one hand and shrinking and warping on the other hand, nobody would worry about moisture in wood. Shrinking and warping look ugly. Mold however, is a hazard for a building, home or office and a health hazard for the people who live or work in the building. Mold in our homes can cause major health issues. Many people live with mold and do not even realize how it is affecting them. Mold can cause upper respiratory problems such as coughing, wheezing, red itchy eyes and asthma like symptoms. Some people with immune system issues will be much for susceptive to mold. Mold will grow in moist conditions that can arise from leaks in a roof or window, pipes, water from plants, or even flooding. Mold remediation can get very costly. It is important to fix the problem and to make sure it does not come back. Sometimes it can be a seasonal problem which occurs when there is a lot of rain. We have a cost effective package that will help you monitor hard to reach areas such as in a crawl space, in a wall cavity, or behind a sink. The S-11 package comes with our mini-Ligno SD/C moisture meter which can read wood and sheetrock in MC%. The meter has a wide measuring range 6-45% which allows the user to measure and monitor the moisture of problem areas. Here is an example of a specific application: How to check moisture levels in a crawl space without having to “crawl” into the space. You need a moisture meter and a long enough cable to reach down to the crawl space. After installing the cable in a floor joist of studs in the crawl space, the other end of the cable is left in a place on the first floor, easy to reach. For measurements, the cable is plugged into the meter and instantly a moisture value is indicated. That value should stay below 16% to prevent mold growth. Items to be ordered are package S-11 (moisture meter mini-Ligno S/DC) or package M-11 (moisture meter mini-Ligno MD/C) includes one cable 6ft long and 1 pair of probes for wood or pins for drywall.
S-11 package wood and drywall – List $178.00
M-11 package wood and drywall – List $105.00
How one customer used the S-11 package to monitor moisture damage.
Here is an example of how one of our customers used the the S-11 package (moisture meter, cable and wood probe)After setting the probe in the wood and connecting the cable (photo 1), the cable was runup through the floor to a closet in the center of the first floor. That way, the moisture content can be checked any time, without having to go back under the house (Photo 2).
The moisture can now be monitored throughout the seasons and it can be noticed weather or not long periods of rain will affect the moisture content in the joists. I will also show if any steps taken to reduce high moisture are actually working. For instance, with a broken water pipe, you can all of a sudden have a very high moisture content in the crawl space. With the monitoring system you can make sure that over time the moisture content falls back to “healthy” levels. Moisture meters can be used in many different ways when working on restoring houses. This is only one of the many applications besides measuring flooring, furniture, siding, moldings, decks, etc. Essentially all materials which absorb and loose moisture should be checked.
Photo above shows another application of meter using built-in pins: the low value clearly shows that at this time there is no moisture in the area and repairs can be done instantly after moldy drywall is removed. The main advantage of Lignomat’s cable system is to be able to measure places that are hard to reach otherwise. I personally had a leak behind the sink and when the new cabinet was installed I put 1 pair of screws in the drywall to monitor behind the back wall of the cabinet. Every once in a while I am able to reassure myself that there is no more problems by quickly testing the site.
If it would not be for ugly deformations caused by cupping, bowing and gaping, nobody would worry about moisture and humidity. However, failed floors and customer complaints have made installers and clients more aware of moisture problems.
Most materials in the building envelope are hygroscopic. They contain a certain amount of moisture, however if there is too much or too little moisture in the air surrounding them, they will absorb or loose moisture. Problems in wood floors occur when there is an imbalance between humidity in the air and moisture in the wood . Wood is a hygroscopic material, which will absorb and loose moisture.
The finish on a floor plank will slow down moisture movement however it is not 100% tight. A wood floor will follow changes in moisture content and relative humidity. Stability of wood depends on 3 values: moisture content, relative humidity and temperature, with temperature having the least influence. (read more click here)
Corresponding values for stable conditions are listed in the EMC chart, one of the most important tables for any floor installer. The EMC chart shows values for 1.2% up to 24.3% wood moisture content for ambient humidity of 5%-95% at temperatures of 300 to 1000F.
For on-line EMC chart go to www.lignomatusa.com/EMC
If the moisture in wood changes, depending on species, wood orientation and exposure time then the wood shrinks and warps or buckles and cups.
For instance, the EMC chart shows, that wood with a moisture content of 10.1% is stable at 55% relative humidity and 700F. No cupping or shrinking will occur, as long as the relative humidity remains at 55%.
- If floor planks measuring a moisture content of 6% are exposed to air at 55% and 700F, the floor will pick up moisture until the relevant EMC value is reached at 10.1%. Wood species, coating and exposure time determine how much moisture is actually absorbed by the wood. However at 55% relative humidity, the floor will never pick up more moisture than 10.1%.
- If floor planks were installed at too high a moisture content (not confirmed at the time of installation), the floor planks will dry out and most probably cup during the months following the installation. At the time of the complaint, the floor planks are dry, which can be easily confirmed by a moisture meter. What cannot be verified at that time, is the initial moisture content, the culprit for the cupping. Since the moisture was not noted at the time of the installation, the installer is the most probably party deemed responsible for any repair work. Protect yourself from claims by using a moisture meter and thermo-hygrometer, when installing a floor.
- All is well, if a floor has been properly installed at 7% wood moisture and the relative humidity in the house stays at 40%. The floor will not suffer any cupping or gaping, as long as the relative humidity does not change. As time passes winter comes with very low relative humidity. RH inside a home can fall below 15%, unless a HVAC system is used. The drop in relative humidity will cause the wood to dry out, shrink and cup. According to the EMC chart, the wood moisture can drop down to 3.5%. Even though the wood may not reach the lowest possible value, as the wood dries out, little gaps become obvious and the home owner is complaining, trying to blame the installer. To protect themselves from claims, that are really not their fault, the installer should explain at the time the job is finished, that low relative humidity values occurring in the winter time can cause the floor planks to shrink and small gaps will occur. Those gaps will go away again during the summer, because of the increased humidity in the air. The only remedy is keeping the relative humidity between the recommended values of 30-50%.
There are meters available to measure moisture in wood and relative humidity in air with hi-precision relative humidity probes, such as the Ligno-DuoTec BW with Lignomat’s RH BluePeg probe. Wood moisture can be measured with the pinless meter function. As a bonus, the Ligno-DuoTec BW comes with dual-depth capabilities. This allows the installer to pin-point moisture conditions in two levels at ¼” and at ¾” deep. The meter can be equipped with the RH Probe for accurate relative humidity and temperature conditions. A data-logger is also an option as it keeps measurements for months or years of relative humidity and temperature in a home, independent of any climate control in the home.
Photo 1 shows a dual-depth, pinless moisture meter used to measuring an engineered floor. Note the depth has been set for ¼” deep to give reliable measurements of the hardwood top layer.
Photo 2 shows the same meter used to check the relative humidity in a gymnasium.
For questions call 800-227-2105
For on-line EMC chart go to www.lignomatusa.com/EMC
For more info on moisture meters go to www.lignomatusa.com
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