QA

Question: How To Read A Moisture Meter

What is a good reading on a moisture meter?

In general, any reading between 6 and 10% is considered normal here. Now if you are testing exterior wood that has direct contact with the surrounding humidity, you can tolerate values that are up to 20%. Things start to get worrying when the meter indicates higher values than 20%.

What should the moisture level be in my walls?

Most houses have varying levels of humidity up to 50%, so moisture levels in drywall can vary from home to home. While relative humidity can have some effect on moisture levels, drywall is considered to have an appropriate level of moisture if it has a moisture content of between 5 and 12%.

What is normal moisture level in concrete slab?

Acceptable moisture levels in concrete according to ASTM standard, when testing via ASTM F2170, the RH level of a concrete slab needs to be at or below 75% — unless the flooring system manufacturer provides alternate guidelines. Some flooring system manufacturers have products that can handle 95% RH or more.

What is acceptable moisture level in plaster?

The surveyor on site needs to have some flexibility based on the site, the context and other factors. However, as a rough guide we say anything below 20% WME on plaster is low – above that but lower than 25 to 27%%WME is moderate and Over 27% or so can be thought of as high (ish)….

How can you tell if concrete is dry?

Testing the Concrete for Dryness You can’t tell if the concrete is dry just by looking at its surface because the surface is nearly always drier than the center of the slab. The only way to know if the concrete is dry is to test it.

What is a normal moisture reading in a basement?

When your basement is too humid, you’ll probably be able to feel it. A comfortable basement should maintain a humidity level of 30 to 50 percent — however, those may differ depending on your climate.

How do you measure moisture in a slab?

When measuring moisture in concrete, the best and most reliable method is to use the ASTM F-2170 testing method. Under this method, you’ll use a thermo-hygrometer with in-situ probes, along with a series of prepared holes, to get readings of relative humidity deep in the concrete slab.

Can moisture meters give false readings?

FALSE POSITIVES Moisture meters are subject to false positive readings for a number of reasons that are well documented in the industry. Non-invasive meters have more false positives than penetrating meters. The most common cause is metal hidden in or behind the material being checked.

What moisture level mold grows?

What Humidity Does Mold Grow? As previously mentioned, mold thrives in humidity levels of 55% or more. Humidity levels can vary throughout the house. Common areas of concern are kitchens, bathrooms, and laundry rooms where water is frequently present in large quantities.

How do I know if my concrete floor has moisture?

The best way to test for slab moisture is with relative humidity testing (ASTM F2170). RH probes are embedded into the slab or inserted through small drilled holes. This method indicates the moisture condition throughout the slab.

Will concrete dry if too wet?

When a concrete mixture is too wet, it causes a greater amount of shrinkage during the drying process than is needed. As a result, the concrete has a great likelihood of cracking and for those cracks are likely to be a fairly good size. A watery mix actively reduces the compressive strength of the dried concrete.

How long does it take a 4 inch concrete slab to dry?

Your concrete should be solid enough to walk on, without leaving footprints, after anything from 24 to 48 hours. By seven days, your concrete should be cured to at least 70 percent of its full strength.

What percentage of moisture should be in house?

Every home is different, but a level between 30 and 40 per cent humidity is typically ideal for keeping your home warm and comfortable in the winter, without leaving condensation on the windows. In the summer, that level can be higher, between 50 and 60 per cent.

How do you calculate relative humidity in concrete?

The new industry standard for measuring concrete RH is the in situ concrete relative humidity test as described in the ASTM F2170 standard test method. It involves drilling a hole into the concrete and using an electronic relative humidity probe to directly measure the moisture in the slab.

How accurate are moisture detectors?

Most moisture meters are accurate! In general, high-end moisture meters give accurate readings to within less than 0.1% on most surfaces.

How accurate are moisture readers?

A high-quality moisture meter used on the right material can be accurate to within less than 0.1% of the material’s moisture content by weight. However, a low-end moisture meter can be wildly inaccurate.

Are moisture meters accurate for drywall?

A moisture meter can accurately detect moisture for drywall. Depending on the type of moisture meter being used it can be accurate down to 0.1% of moisture content in drywall.