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How to install solid hardwood flooring over concrete

Hello everyone!

 

We had a topic earlier on the community regarding the do's and don'ts of installing solid hardwood floors over concrete. As I wrote in the post, you can go with other options such as engineered or click-lock real wood flooring. Anytime you are installing real wood over concrete, regardless of what thickness or material it is, you will need to do some preemptive steps to ensure your wood floors will not cause any issues after they are installed. The purpose of this post is to inform you of some other items as well as a diagram that wasn't in that previous post.

 

Concrete as a substrate is a porous surface, and to make sure any water will not come through and do any warping, cracking, or failure is to make sure the concrete is not touching the wood planks.

 

This can done several ways:

  1. by building a new wood frame floor above the slab alongside a plastic vapor barrier then covering the wood frame with plywood, then using a floor stapler to fasten the planks down to the plywood
  2. installing plywood down with glue or concrete screws directly into the concrete slab and then fastening the boards down over plywood.....if the room is large enough, such as an 8ft by 8ft or larger, a few installers I have spoken to simply install the plywood as a 'floating' system without screwing or gluing to the floor and fasten the plywood with deck plates and fit the wood within a 1/4" gap where the floor will meet the wall. The sheer weight of the wood as one piece keeps it from sliding drastically.
  3. use a urethane-based glue  and notched trowel directly onto the concrete. This is done on hardwood floors at or above grade. This type of glue is important, so as to ensure the adhesive will not allow any moisture to come in contact with whatever wood you are working on.

 

Either way, the trick is here is not letting the wood come into direct contact with the slab without some sort of protection. Solid hardwood floors secret into lasting a lifetime as a floor are due to several things such as how they are installed as well as the wood itself. Wood as you may or may not know, is a breathing and flexible material. It can shrink and expand almost as much as when it was still on the tree. Putting wood directly over concrete can make this movement go the wrong way if improper steps or precautions are taken.

 

In this post, I will be referring to installing solid plank hardwood flooring. They come in a variety in thicknesses and widths and while they can be installed over concrete, it is imperative you take the necessary precautions to ensure the project will work. Also, be aware of most solid hardwood plank manufacturers will not guarantee their product will work in areas that are below grade, such as basements.

solid hardwood section.JPG

Also, some brands of hardwood floors require their floors to be stapled or nailed down, with no glue at all needed.  However, getting the right materials will ensure you can have a beautiful wood floor that will last for a long time.

 

In this diagram below, you can see how the hardwoods are set over a set of "sleeper" or slats that are 2 x 4s. They are typically pressure treated, under the plywood to ensure the wood can breathe and not allow for any moisture to come through. This is achieved by way of a plastic vapor barrier put down first before anything else. While you can glue directly to the subfloor with a urethane-based hardwood floor adhesive or use plywood and screw the plywood directly into the concrete via a screw such as  Tapcons; this is one of the most common approaches I have seen to install a solid plank hardwood floor over concrete

cross section of hardwood floor over concrete.JPG

 

For years, installers and flooring contractors have done various methods of using the sleepers and plywood, or just the plywood, or even just using a urethane-based glue directly onto the concrete. In "building up" your floors with wood, even a small amount of plywood, you will need to remember that any floor moldings, jambs, transitions, and doors will most likely need to be taken out and reinstalled. In the case of doors, they may even need to be sawed down to ensure an accurate fit.

 

So there you have it, 3 of the most common ways to install solid hardwood flooring directly over a concrete subfloor!

 

Let us know if you have any further questions!

aboveaveragejoe

 

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Posted 2011-10-17T18:02:33+0000  by Joseph_HD_ATL Joseph_HD_ATL
 

The most probable method is to get firm nich on then you fix it with plywood.

 
Posted 2012-10-08T12:58:27+0000  by AmandaFremen

Hey Nicole,

 

Welcome to the community and thanks for your question!

 

Deck plates are an item found where our deck support supplies are located in your local Home Depot store, usually in the lumber department. I also spoke to my stores installation expeditor who's been in the business much longer than me, and he states that if you don't have access to a deck plate, you can also use a mending plate aka a flat brace that is available in our hardware department. Shown below, you would center one of these over where two panels of the plywood subfloor meet. Simply use a small screw at a slightly shorter thickness of the plywood to fasten them together.

mending plate 

 

Depending on how large the area you want new wood floors to put installed will determine how much plywood and plates to use. A good rule of thumb is to use one plate at least 18"-24" inches over the length of the plywood. For the edges, this isn't needed.

 

I hope this has cleared up any questions you may of had regarding using a plate system.

 

Let us know if we can further assist you.

aboveaveragejoe

Posted 2012-10-06T14:52:51+0000  by Joseph_HD_ATL

hi i was interested in the part where you can possibly lay the plywood over the concrete w/ vapor barrier

and not glue or screw it but use deck plates.

I am unfamiliar with deck plates.  can u give me more info on what these are ?  

thanks nicole 

Posted 2012-10-05T19:15:29+0000  by jnkellum
 
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