Hardwood Flooring Installation 101: Moisture Testing

Establishing the moisture content is a critical component of quality control in hardwood flooring installation process. Therefore, every floor installer has to be informed of the amount of moisture content on subfloors and the wood.

Moisture humidistats and meters are the most important performance tools. If your installer does not have any of these tools, then they are obviously not aware of the significant relationship between moisture and wood. Continuing with an installation process constitutes the acceptance of the work site conditions by the installer or technician.

A wood-based subfloor should be within an average 2% moisture content of hardwood flooring. The average humidity of the house must be between thirty to fifty percent of solid wood and thirty-five to fifty-five percent for engineered hardwood before, during and after the installation job. A minimum reading of 10 moisture taken per 500 square feet at intervals of four0inches apart, recording the lowest and highest measurements.

There are numerous kinds and brands of moisture reading meters. The Pin-type readers penetrate into the wood to get the moisture reading. Non-destructive pin-less meters obtain moisture measurements without penetrating the wood. More often, the pin-less meter readers give readings, which are not accurate entirely, but provides a fair reading of moisture content. Meters that are more expensive on the other hand have adjustable settings thus more precise. However, glues in the subfloor affect them.

The only ideal and accurate method of measuring the moisture content of wood by weighing the piece of wood then let it dry until there is no moisture remaining in it. Weigh the dry piece, less the dry wood weight from the wet wood weight, and divided by the dry weight.

MC = [(initial weight- dry weight)/ dry weight] x 100%

Example: 400 grams - 370 grams = 30 grams, divided by 370 grams x 100 = 8.1percentage moisture content.

Hygrometers or humidistats are readily available for purchase. Buying and using two units will maintain accurate results. Take and note these readings throughout the job.

Before testing a concrete slab, it should be at least forty-five days old. Use a Calcium Chloride test, which is always accessible at The Big Box Stores. The moisture level readings obtained using the Calcium Chloride test must not exceed a maximum of 3lb per 1000 square feet.

The time duration taken by concrete to cure can cause delays on the job site. A wall or concrete slab in the best drying conditions with a large dehumidifier in operation will dry at approximately one-inch per month. Without these circumstances, the concrete wall or slab may only dry at a quarter inch per month. Concrete heals by hydration when moisture reacts with cement powder, providing the concrete its strength. However, the mixture always contains more water than is required for hydration reaction, becoming more prevalent with the utilization of lightweight aggregate that tends to retain moisture. In many floor slabs, there could be up to fifty gallons of extra water for every cubic yard of the pour. Using a dehumidifier with constant airflow over the plate surface will fasten the process. When the slab dries, it is recommended to use a concrete sealer or a recommended adhesive.

Radiant heating in such floors, therefore, must be turned on to a minimum temperature of 22 degrees, seven days prior, to eliminate residual moisture before installing wood flooring.