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“Mice Squeak, Your Floors Should Not” by Phill Barrett

Some people feel squeaky floors are an inevitable part of the home construction process. But actually, floor squeaks are almost always a symptom of improper design, poor installation, or the improper use of materials. The most common causes of a squeaky floor include: poorly nailed sub-floor sheathing, missing joist hangers, missing nails on the joist hangers, improperly installed metal cross bridging, “shiners” (nails that just miss the joist), improper application of sub-floor adhesive, and excessive shrinkage of materials. With the ever increasing use of engineered wood products (EWP) such as engineered I-Joists, Laminated Veneer Lumber and OSB sub-floor sheathing, the amount of floor squeak complaints have reduced. However, issues can still arise on the installation side of the equation or with the use of solid sawn lumber.

Care must be taken to ensure that every component is installed as prescribed by the engineer or the manufacturer. For instance, Simpson Strong-Tie Company provides a nailing schedule in their product catalogs for every piece of hardware they manufacture. Following the nail schedule for the hardware you are using will eliminate some squeak issues and result in a better-built floor. According to the American Plywood Association (APA), solid sawn lumber leaves the mill with a moisture content between sixteen and nineteen percent. Four to eight months after installation, all components will reach equilibrium moisture content between six and ten percent, depending on location. That’s a difference of up to ten percent. Engineered Wood Products, at the time of manufacture, range between four and twelve percent. As you can see from the numbers, engineered wood products are more stable and less likely to shrink or swell, reducing squeaks. Mixing solid sawn lumber and engineered wood products is another area of concern. An engineered floor system should contain only engineered products, because of the difference in moisture contents.

An often overlooked issue is the sub-floor adhesive. Often, the manufacturer’s directions are not or cannot be followed due to time and weather constraints on the job. Some framers have been known to warm the tubes of adhesive on their engine block and install the adhesive on frozen lumber in the winter. During wet weather, some framers have been known to apply adhesive on wet framing members and it does not adhere properly. Other times, material is wasted by cutting the applicator tube too big, or not enough material is used by cutting the applicator tube too small. Sometimes, adhesive is not applied at all for whatever reason.

A resolution to adhesive issues is being championed by National Lumber. We now pre-apply sub-floor adhesive to our engineered wood products at our facility in Mansfield, MA for the same per linear foot price of 2-3/8” beads glue. The process applies two consistent beads of the adhesive directly onto the flange of engineered I-Joists in a controlled environment. Our adhesive meets ASTM requirements for sub-floor adhesives. The adhesive is applied using a hot melt system and is then covered with a tough clear plastic strip. At the job site, the framer will install the I-Joists according to the supplied layout in their usual manner. When the time arrives to install the sub-floor sheathing, the framer simply needs to remove the protective plastic strip, lay down the sheathing and nail. There are no more substandard or missing sub-floor adhesive problems with this system. The adhesive has a 24-hour cure time and stays flexible after curing, unlike most sub-floor adhesives that harden like concrete. The flexibility allows the framing members and sheathing to expand and contract naturally without fear of breaking the adhesive bond and causing a squeak.

To learn more about how National Lumber can help with your next project, call 800-370-WOOD.

- Phill Barrett, National Lumber Engineered Wood Products Division

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Stop Squeaking Floors: "Mice Squeak, Your Floors Should Not!"