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The Importance of Subfloors for Solid Hardwood Flooring

The look of solid hardwood lends a timeless sense of elegance to interiors. Before installing this type of quality flooring, one of the most important things to consider is what will lie underneath it. Actually, this is not just a mere consideration – it is crucial part of a hardwood floor installation.

hardwood (oak) floor over wood sub floor

A solid hardwood floor is a reliable flooring choice that will add long term value to your home. But like any investment, it needs protecting, and you need to judge whether or not you’re making the right decisions to maximize your investment. When planning your installation, it’s important to keep in mind that a solid hardwood floor is only as good as its subfloor. A proper subfloor will be the unsung hero of your solid hardwood investment, while the wrong subfloor will cause you problems.

Installation factors to consider

The most common way a solid hardwood floor is installed is by means of nailing or stapling the boards directly to the subfloor. As such, it is important that the subfloor be made of a material that will hold a nail or a staple for the life of the solid hardwood floor. Substrates like vinyl, glued-down carpet, concrete or ceramic tile are not suitable for the installation of solid hardwood flooring.

When doing an on-grade installationat the level of the ground outside the space – it is important to consider not only the subfloor, but also the ventilation quality of any crawlspace or basement underneath. Hardwood flooring will be affected by moisture underneath the floor as well as on the top surface – that is the nature of solid wood.

For an above-grade installation, meaning that the space is above ground level, it is important to consider whether the rigidity of the substrate is adequate to support the solid hardwood floor being installed.

For below-grade installations, for example an installation in a basement, moisture levels are usually higher in these circumstances. It’s important to note that a limited number of hardwood flooring options are suitable for below grade installations because excessive amounts of moisture can mean disaster for solid hardwood floors, causing them to warp and swell. However, if you have your mind set on a hardwood floor in this kind of space, there is another alternative: an engineered hardwood floor. Engineered hardwood flooring is suitable for installation on concrete subfloors because it can be floated, or directly glued to the concrete and is less affected by expansion due to humidity, or other environmental factors which affect below grade installations.

Lasting value

A solid hardwood floor can add real value to your property, both in terms of it aesthetic effect and market value. Making sure you have the right subfloor for your solid hardwood floor is not only a way to extend the life your floor, but also a way to nurture your investment.

Do you have an appropriate subfloor for a hardwood flooring installation?

Click here to take a look at our stunning online selection of hardwood flooring. Discover the right floor for your installation!

(9) Comments

  1. I have a 200 plus year old Vermont port and beam farm house. The floor beams are 4 x 6 approx. 2 feet on center with 5/4 fir or hemlock sub floor. The finish floor is 3″ wide 3/4″ tounge & groove maple nailed directly to the subfloor. I need to replace the floor in the kitchen area (325 sq. ft.) with something that looks similar to the original floors. The floor has some sag from one side of the room to the other and is not perfectly flat, but the original floor was nailed down well and managed to follow the sags. What type of flooring would you recommend and is the current subfloor sufficient for nail down installation?

    • BuildDirect Product Expert Team
      BuildDirect Product Expert Team - Reply

      Hi Ron,

      Thank you for getting in touch! I would definitely suggest trying to use some sort of self leveling product to help even out the floor. You are extremely limited in your options if the floor is not flat and level. You can try nailing down hardwood again but we can’t guarantee it is going to work. Any type of floating floor will not stay stable without a level surface beneath. You can also look into flexible porcelain tile but I would suggest getting an installer to take a look at the area to recommend some option. Please let us know if you have any other questions!

  2. Installing bamboo flooring. Existing floor is 3/4″ oak. Can bamboo installation be applied directly on the oak floor?

    • BuildDirect Product Expert Team
      BuildDirect Product Expert Team - Reply

      Hi Ray,

      Thank you for your inquiry! If you are using a floating floor you can install on top of the oak floor as long as it is clean, dry, flat and level and you have the proper underlay. If you want to nail or glue down you will need to take up the oak floor and install over the concrete or 3/4″ plywood subfloor. Please let us know if you have any other questions!

  3. I have purchased engineered hardwood from you and want to nail/staple it down. The subfloor has 3/4 plywood with particle board glued on top. The particle board would be difficult to remove cleanly. Would it be adequate to still staple or nail down the engineered flooring but using staples/nails that are long enough to penetrate the particle board and go into the plywood?

    • BuildDirect Product Expert Team
      BuildDirect Product Expert Team - Reply

      Hi Robert,

      Thank you for getting in touch! Unfortunately that would not be the best option because if the OSB separates from the plywood for any reason there could be issues with squeaking or the flooring coming up. We would recommend screwing down 3/8″ plywood on top of the OSB to ensure everything stays down and secure. Please let us know if you have any other questions!

  4. Can hard wood be put down over mdf? And I was considering gluing also. The mdf is in great shape and has been down for thirty years and it looked good when the carpet was replaced! It is glued and screwed and it looks like it might be sealed at the joints!

    • BuildDirect Product Expert Team
      BuildDirect Product Expert Team - Reply

      Hi Stan,

      Solid Hardwood must be installed over a 3/4″ CDX plywood subfloor. If you are thinking of using an engineered hardwood though, you could either glue or float it over the MDF.

  5. Pingback: Lastest Floor Hardwood Maintenance News - Janitorial Service

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