Preparing for a Steller Floor: Site Recommendations

Steller Floors can provide exceptional flexibility over a range of subfloors and indoor climates.

Steller planks are made of high-quality solid hardwood and float over the subfloor without nails or glue, so site preparation is quite simple. 

Basic Site Recommendations:

  • A flat, firm subfloor
  • A moisture barrier 
  • A controlled, indoor climate
  • (Optional) Subfloor heat guidelines

Subfloor Specifications

A Steller Floor assembly is specifically designed to be installed on flat, firm, and continuous surfaces made of OSB, plywood or concrete. It is important to note that the clips used in the assembly are not self-supporting, which means they cannot be installed over free-spans.

We recommend that the subfloor should be flat within an 1/8" over an 8-10 ft area, including deflection. Deflection is a common occurrence in building materials, and it refers to the degree of bending or sagging in the subfloor. Therefore, subfloors should not be exceptionally "bouncy" or "squishy," as it can lead to an uneven installation of the Steller Floor. If your subfloor is uneven, bouncy, or squishy, we strongly advise remediating your subfloor before installing your Steller Floor. 

Moisture Barriers

Steller Floors are made of solid wood which, while beautiful and long lasting, is also a porous material that can absorb moisture. Moisture can come from a variety of sources, including groundwater, plumbing leaks, or high humidity levels. 

To prevent moisture from affecting your Steller Floor, we recommend using a moisture barrier. A moisture barrier is a layer of material that is installed between the subfloor and the hardwood floor. Its purpose is to prevent moisture from seeping through the subfloor and reaching the underside of the hardwood planks. A moisture barrier is particularly important if your subfloor is made of concrete, as concrete tends to retain and transfer moisture.

A commonly used moisture barrier for Steller Floors is 6 mil polyethylene. This is a thin, flexible plastic sheet that can be easily installed over the subfloor. It is available at most hardware stores and is relatively inexpensive.

To install a moisture barrier, simply roll out the polyethylene sheet over the subfloor and secure it in place with tape or adhesive. Make sure that the sheet covers the entire surface of the subfloor and that there are no gaps.

A Controlled, Interior Climate

For all wood products, it is important to maintain a controlled indoor climate. This means keeping the humidity levels between 35% and 50% RH ("relative humidity"). High humidity levels can cause the hardwood planks to expand, while low humidity levels can cause them to shrink. Sudden temperature changes can affect humidity and so we recommend keeping your interior climate between 65 and 85 degrees Fahrenheit.


Steller Floors are manufactured at 45% RH to match the interior preferences of most humans and the typical target for most residential HVAC units. If your interior space matches this range, you do not need to acclimate your floor before installation. However, if your home is substantially drier (e.g. desert climates) or wetter (e.g. coastal areas) we recommend allowing your floor to acclimate to your interior space prior to installation. Acclimation times will very depending on your project, we recommend allowing two weeks for every 5% outside of the recommended RH range. 

Expansion Gaps

Within the human comfort zone, solid hardwood floors are expected to expand and contract in response to changes in humidity. For this reason, Steller Floors provides a 5/8" foamed nitrile gasket to use as a spacer under baseboards. This spacer and the expansion space it reserves is designed to accommodate a change of 10% RH across a 20-foot span perpendicular to the length of the planks. If you expect your space to vary more than 10% RH or if you have a substantially wider room, please contact us for more information.

Subfloor Heat Recommendations

Because Steller Floors float, they are easily assembled over most subfloor heating systems. Even better, you can access the subfloor heating system from any plank or planks in a Steller Floor - even in the middle of the room!

Since Steller Floors are made of solid wood, Steller Floors are the same as other solid hardwoods with respect to subfloor heat. We recommend limiting the heat below the floor to 80 degrees F.
With this in mind, most types of subfloor heat are compliant including hydronic heat (hot water in pipes housed in the subfloor), and polymeric heat (large sheets of plastic with silk screened carbon that warms the subfloor. These options are both widely available, and for more details about these product please contact the manufacturer of your choice.
However, most electric heat mats with heating coils will get too hot for use underneath a Steller Hardwood Floor. We also don't recommend this style of electric heat because it has higher fire risk than alternatives.

Reach out for Steller Support!

We are here to help you with your flooring project and if any questions begin to vex you, don't hesitate to reach out to us. We can help you troubleshoot over the phone, by email, or by zoom appointment! 1-800-955-7671 or