View Full Version : Floor Inlay Substrate

John Esberg
07-05-2006, 1:36 PM
Hello everyone,

I've been using Baltic Birch plywood as the substrate for making floor inlays. It works just great, but I was wondering if anyone has ever experimented with other materials?


John "DAK" Esberg

Michael Wells
07-08-2006, 11:56 AM
Hi John,
Having owned a hardwood flooring company that did a huge amount of inlay work as well as medallion sets, I have to tell you that regular old pine plywood in a good grade is about all that a floor guy ever wished for!

Baltic Birch is fine, as is a high grade mahogany, but they aren't really any more preferential than a good grade of pine plywood. The reason for using plywood as a substrate is the strength and resistance to expansion and shrinkage which cause a great deal of flooring problems. Plywood is less apt to expand and contract than the species placed on it and therefore acts as a stabilizer.

We looked at the function of chipboard, masonite, and all sorts of other things such as wonderboard tile backer board, as an alternative. We never found anything as stable and inexpensive as plain old A/B Plywood!

Hope that helps.

John Esberg
07-10-2006, 3:14 AM

I first tried 5 ply baltic birch from Home Depot. It changed shape with the weather every day.

Now I custom order in 60" x 60" x 0.5" sheets of 9 ply baltic birch. It's pretty tough and doesn't budge a bit. At $30 a sheet, I'm pretty happy.

I'll certainly look at using that kind of ply wood.



Michael Wells
07-10-2006, 1:55 PM
Wow, where the heck are you living?? The dimensional stability of plywood is almost always (as far as I know) going to be better than the solid wood you are placing over it!

I can't imagine that you would have had that problem, unless you are living somewhere that itthe weather changes so drastically from day to day that it would cause a problem.... and then you wouldn't have any luck with any wood flooring, save oiled teak or Koa, etc.

That leads me to believe that there was something wrong with the plywood itself and not the structure of the installation. Heck, I've even used standard underlayment such as 1/4" 3-ply Phillipine Mahogany plywood (Luan) and had good success.

In the interest that I may not have understood you correctly, you might want to explain movement to me!! I took that to mean expansion/contraction. If that is the case, the only thing that I can think of is if you are using a soaked piece of ply ( ie. warpage), or that it isn't the plywood at all that is doing the moving? You may want to moisture check the overlay wood and the plywood to see what you are dealing with. Maybe the top wood is moving leaving you to believe that it is the plywood?? I honestly have never had that kind of problem with the plywood, except for flooding!

One other thing is that if you are using a moist top wood to begin with and then adding a waterbased glue in large amounts, you might just possible be causing the top wood to suck up the glue moisture during the cure. Unlikely, but possible!

John Esberg
07-10-2006, 4:10 PM
For glue I first started with Tightbond III. Waterproof, but still had water. I've since moved on to using Gorilla glue, which works like a champ. I find it does a perfect job of filling gaps when needed.

Believe it or not, I used to be able to tell you how much deflection I would get in a piece simply by comparing the humidity on the day of cutting/assembly and comparing it to the weather channel. I would actually prep the pieces by submitting them to either a humid bedroom or a dry space to get the bending to a minimum just so I could drum sand the piece.

To me it appeared to be the inlay on top. On humid days it was always guaranteed to raise the center. On dry days, I would have a bowl.

I tried jumping to 1/4" baltic birch (3 ply) with a design on top and a simple design on the bottom. The end result was like a bird flapping its wings over a really slow rate of a couple days as humidity changed.

My only solution has been to use 9 ply baltic birch. Works great.

As for moisture content of the top layer, I don't have a moisture meter. I just take the wood home, space it out and let it dry. When the wood stops moving (aka 20% or so is done warping) I go to work.

I buy my wood directly from a mill in buffalo. The price is golden.

So, do you test you inlay pieces with a moisture meter before use?

Hope to hear from you soon,


Michael Wells
07-17-2006, 2:30 AM
I do moisture check any wood that I don't have adequate time to acclimate before working with it. But if you are having that much problem, I would really watch the MC of the wood that you are using, including that of the plywood to make certain that it is average for your area.