“Norma, In our continuing saga of re-doing our home, we are now in the process of having to choose new wood flooring. There are so many types of “wood” floors on the market. I know I do not want the laminated “wood”, but I am confused as to which type of “real” wood flooring would be best to put over a concrete slab. Can you give me some pros and cons? Can you also tell me how these would be laid down?” – WYSK Reader Jean B

NV: Great questions, Jean!

It’s true that there are so many real wood flooring choices, plus the added factor it’s going over concrete – you’re right to question it all!

First things first, to help make your wood floor choice you need to be aware of this major distinction – hardwood flooring can be broken down into two categories – solid hardwood and engineered hardwood.

Hardwood Flooring

Solid hardwood is just that – a single piece of hardwood milled to 3/4″ thick planks or boards. (FYI, in wood floor lingo, wide floor planks, 5” or more, are commonly referred to as boards.) Solid wood flooring naturally reacts to humidity and will expand and contract with changes in your home’s relative moisture. To compensate for this movement, there must be an expansion gap between the floor and the wall, which is concealed with base/floor molding. If higher levels of moisture are present, the boards could swell and cup, or buckle.

Engineered hardwood is indeed real wood, however it’s stacked in layers (plies), where only the top layer is a veneer of the desired wood. The other 3 (or more) core layers can be a combination of plywood, high density fiberboard, or hardwood. The way the layers are bonded to one another creates a flooring that is more resistant to changes in humidity, therefore more stable than solid hardwood floors in that respect.

Moisture mojo is very important when it comes to choosing a hardwood floor!

This moisture mojo is muy importante in your floor choice, Jean, because a concrete slab, even above grade, has increased levels of moisture, which would put the whammy on solid hardwood, making engineered hardwood a better option over concrete!

There are a few things you really need to know when choosing engineered hardwood flooring:

  • The thicker the top veneer the more expensive the floor will be, BUT the more durable and re-finishable. Know that a veneer under .6mm CANNOT be sanded and refinished, should that ever be needed.
  • The more core layers, the more moisture tolerant and stable.
  • Engineered floors come in various thicknesses that allow for a variety of applications without awkward transitions between different flooring materials and doorways (i.e. bridging a tiled kitchen to an adjoining room).
  • Generally speaking, engineered hardwood is less expensive than solid hardwood, but beware of “too cheap” as it may be telltale of poor quality that won’t age well.

Let me add, even given the moisture resistant nature of engineered hardwood, I don’t recommend them for basements.

installing hardwood floor

As for the install, the concrete must first be sound, smooth and level – so sorry, but that old linoleum and carpet have to come up!

Then how the engineered hardwood floor goes down will largely depend on the manufacturer. These are general scenarios:

  • If the planks are glued down, the concrete must first be painted with a waterproofing membrane sealant, then a specially prepared adhesive would be used to glue the planks in place.
  • If planks are nailed or floating (tongue & groove or snap-lock type) a moisture barrier must go over the slab before laying down the floor. Generally sheets of 6-mil thick polyethylene plastic are used. From there, typically pressure treated ¾” plywood is put down over the moisture barrier. In some cases, installers will first install “sleepers” (1 x 3s or 2 x 4s on the flat) to create “floor joists,” then screw the plywood to them in order to really minimize how much contact the wood has with the slab.

Now the planks/boards have a proper subfloor over the concrete!

Jean, there’s certainly a ton to know about hardwood flooring choices and installation, far more than I can write about here, but with these tips and install highlights I’m sure you’ll make the right hardwood floor choice for your space, with confidence!

Norma sig

Got A DIY Question? Ask-The-Expert!

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Fix-It Friday is an exclusive Women You Should Know® editorial series authored by seasoned veteran of home improvement, Norma Vally, the former host of Discovery Home Channel’s series “Toolbelt Diva” and a show on Sirius Satellite Radio by the same name. The weekly column is designed to inspire women – weekend warriors, aspiring handywomen, and even seasoned DIYers – to take on home repairs and maintenance projects with confidence and gusto.