Tracking a floor’s moisture content is key to a successful hardwood flooring installation. We asked moisture meter manufacturers to weigh in on whether pin or pinless meters are better for testing moisture, whether there are any differences between testing solid and engineered hardwood, and how to go about measuring moisture in bamboo floors.

Pin vs. pinless meters

According to Grete Heimerdinger, Lignomat’s vice president, both pin and pinless meters have their benefits and trade-offs. Either one can be used by a flooring industry professional to check for moisture.

“Pin meters are more cumbersome to use, but they look down into the floor and indicate differences between surface and core moisture. When using pin meters, different calibrations may be required for a mixture of wood species. Additionally, sometimes the glue affects the measurements of the subfloor,” she explained. “Pinless meters, on the other hand, are easy and fast and make no pinholes. They indicate the average moisture for the measuring depth. A lot of measurements are available in a short time; however, they look across the floor.

“Pinless meters are great for pinpointing moisture conditions for repeated measurements over time—during acclimation, during installation, at the final inspection before use and during use. This is especially true for dual-depth meters. Our SD and SDM meters have two independent sets of calibrations—one for 1/4-in. deep and one for 3/4-in. deep. Standard pinless moisture meters have a fixed 3/4-in. measuring depth.”

She explained the dual-depth meters further. “If changes are noted in the 1/4-in. measurements, the difference comes from adjustments of floor moisture to the surrounding relative humidity. The wood could have dried out or absorbed moisture from the surrounding air. If changes are noted in the 3/4-in. measurements, the difference comes from absorption of moisture from the subfloor.”

Jason Spangler, Rapid RH product sales manager for Wagner Meters, said he prefers using pinless meters. “Pinless meters will allow for full thickness measurements (up to 3/4-in. usually) without damaging the wood. The amount of wood measured with each pinless measurement is also greater (1 1/2-by-2 1/2-in. scan plate) than with a pin meter, so with the same number of measurements, a pinless meter would measure more wood overall. Also, pinless meters allow for wood to be measured more quickly, because there is no need to insert pins for each measurement.”

Tramex CEO Andrew Rynhart stated that the best way to obtain accurate readings is by using both types of meters. “Pin meters will be more accurate than pinless meters, but they will leave marks in the material being tested. Therefore, the best option is to combine pin with pinless readings to accurately test a large area with minimum damage.”

According to Tom Rochenski, Protimeter’s national sales manager, pin meters are the best option when working with hardwood and plywood subfloors as “they will give you an actual percentage of moisture in the wood, or WME (wood moisture equivalent).”

“Pinless meters are very good at detecting moisture problems in floors because most meters will measure 3/4-in. below the surface. A good-quality, non-invasive meter will give you readings of moisture under the hardwood and read into the subfloor in most cases,” he said.

Rochenski added, “As a rule of thumb you can use either pin or pinless meters on solid or engineered flooring. Also, you always want to make sure that the wood flooring being installed—whether hardwood or engineered—is acclimated to the installation site for at least three days.”

Moisture testing in bamboo

Bamboo can present challenges to accurate moisture testing since technically the product isn’t even a wood. Problems can also arise when working with strand-woven bamboo, which is extremely dense and acclimates at an unhurried pace. However, certain steps can be taken to ensure that test results are as accurate as possible.

Heimerdinger noted that “Lignomat’s moisture meter Ligno-Scanner SDM has specific calibrations for bamboo. The calibrations preprogrammed in the Ligno-Scanner SDM are based on the wood moisture equivalent, which means if the meter indicated 9%, the bamboo floor is as stable as wood at 9%.”

Spangler said that “bamboo, in general, is different and almost requires custom meter settings based on various bamboo manufacturers’ products. We continue to test various manufacturers’ products to give appropriate settings and gather additional data.”

He added, “Moisture testing strand bamboo is usually best served with a pinless moisture meter. Due to the construction of strand-woven bamboo, which uses adhesive and very high pressure to bond the bamboo strands together, pin meters may penetrate the adhesive, causing a false reading.”

Rynhart remarked, “Engineered floors can be tested in the same way as solid wood with a pin meter if the pins are pushed into the hardwood top layer. Bamboo, however, is a grass and cannot be tested in the same way as wood. Calibrating wood meters for bamboo can lead to problems, as each type of bamboo can be different depending on the pressure and glue used in the manufacturing process. It is better that a standard calibration is used by the manufacturers to set moisture content readings.”

Rochenski also believes bamboo can be difficult to measure. “It depends on the specific species of bamboo. Some species can be very hard like maple or others can be soft like pine flooring. It would depend on the flooring installer to identify the density of the bamboo they are installing. You can usually find a cross-reference chart from the meter manufacturer to identify the hardness of the bamboo being installed. Then use a good-quality meter to measure its WME percentage.”