Picture of a moisture meter measuring the moisture content of a fence

How to Use a Moisture Meter

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Matt Stone

Using a moisture meter is an essential step before you start a new staining project. However, learning how to use a moisture meter is not as straightforward as it seems. There are a few tips and tricks you must know to get an accurate reading.

I have used many moisture meters in my fence staining company and have reviewed recommendations from multiple manufacturers. Read below to learn the simple steps to use a moisture meter accurately.

Setting Up Your Moisture Meter

It is important to set up your moisture meter correctly before you begin. I recommend reading the manual that came with your meter for the specific requirements for your meter. Here are some basic steps that will apply to many meters.

Check Your Batteries

battery

Having a low charge on your batteries can result in inaccurate readings. If you have a battery tester, make sure the batteries are in good shape before you begin. If you have not used the meter for a long time or are not sure about the batteries, it is safer to replace them.

Set the Correct Wood Type

Most moisture meters will come with several settings for measuring different things. For measuring the moisture content of wood you will either need the softwood or hardwood setting. Using the incorrect setting can cause your reading to be inaccurate.

Which setting you should use will depend on the type of wood you are measuring. Below are some common wood species of hardwood and softwood. For a more comprehensive list, see softwoods vs hardwoods.

Softwoods

  • Pine
  • Cedar
  • Fir
  • Redwood

Hardwoods

  • Oak 
  • Maple
  • Walnut
  • Poplar

How to Use a Moisture Meter

There are two main types of moisture meters. One type uses two pins that are inserted into the wood to measure electrical resistance. The other, pinless type, uses a pad placed on the surface of the wood to measure the electromagnetic field in the wood. The way you use them is slightly different.

These are what the pins look like on a pin moisture meter.

Using the Moisture Meter

  1. Turn the moisture meter on.
  2. Check the settings to make sure you have the right wood type selected.
  3. (For a Pin Meter) Press both pins firmly into the wood. Make sure that each one penetrates the wood fully.
  4. (For a Pinless Meter) Place the measuring pad flat on the wood surface. Make sure to apply a little pressure to get firm contact between the wood and the meter.
  5. Read the number that appears on your screen. This is the percentage moisture content that the meter has measured.
  6. Make sure to measure at multiple locations to get an accurate view of the dryness of the wood.

Understanding the Results

The number on the screen is the percentage of water content in the wood by weight. This number will rarely be zero. Because wood is hygroscopic, it will absorb moisture from its surroundings, even the humidity in the air. 

Stain manufacturers will specify the maximum moisture content allowed for applying their stain. A typical range will be somewhere from 10%-15%. 

Many moisture meters will give an audible tone if the wood is too wet. They may also come with a light that turns red if the moisture content is high. It is always best to look at the actual numbers so you know exactly what the moisture content is.

If you measure multiple locations around your project and they all are lower than your stain’s recommended maximum moisture content, you are ready to begin staining.

This wood is way too wet to stain.

Watch out for Metal

Metal in the wood will disrupt the electrical fields the moisture meters rely on for an accurate reading. If you are measuring a fence or deck make sure you are not using the meter next to nails or screws. 

Staining Wood Without a Moisture Meter

Measuring the moisture content of wood before you begin a staining project is the safest way to make sure the wood is ready to absorb stain. If you are a professional, investing in a quality moisture meter is a must. Even if you are a DIYer, there are many inexpensive moisture meters that would be worth looking into.

If you are unable to get a moisture meter before you begin your project you will still want to be reasonably sure the wood is dry. The best way to do this is to give the wood time to dry before you stain. This can range from a couple weeks to several months depending on the exact situation.

Smaller boards like fence pickets will dry out in a matter of a couple of weeks. If you have large beams like those that would support a porch, they may take a couple of months. Pressure-treated lumber will also take months to dry.

If your boards are not already installed make sure to spread them out to promote faster drying. Stacked boards don’t allow air to flow. The boards in the middle of the stack will dry more slowly than the boards on the outsides.

What’s Next?

Once you have determined your wood is ready to stain, you can begin your project. If you are looking to stain a wood fence, read our guide on How to Stain a Fence.

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Author: Matt Stone
Matt has worked as a professional painter for over 10 years. This includes much experience with all types of wood stains. He loves to write about wood stains to help others make good choices to protect their homes and make them beautiful.