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Ask The Doc A Question!

Question:

Doc,

Your prompt attention to our flooring situation in our kitchen would be appreciated very much.

Thank you.

Jon

Answer:



Dear Jon

I do a lot of kitchen floors in hardwood. I don't advise it, but I will do it. The first issue is prefinished or sand on site. The prefinished floor has only one advantage, and that is the tough factory finishes. But beyond that they are just full of open seams. No matter how tightly they are installed, these floors will allow water spills to soak though these unsealed seams. The wood will swell and the seams will open more.

It would be best to have one of these prefinished floors installed, and then coated twice with a durable catalyzed water based finish. And that's the rub, we are not yet sure that these factory finishes will accept another coat of finish on top of it. You may be able to use one of the chemical prep systems as described in the maintenance article available in the search box at the top of this web page. But these prep systems are new and quite expensive. Remember you will still have to coat these factory floor finishes every 4 years at least.

Engineered or laminated wood would be OK but short lived. The newer 2-3 ply laminated floor are a poorly designed product in my opinion. These are very thick slices of wood and not veneers at all. They will tend to act much like solid wood. By that I mean, when they get wet, (and in a kitchen they will) they will swell and buckle as they are dimensionally unstable (too wide for the depth).

The 3-ply material has been vexing the new home builders for the last few years. They install this material thinking they won't have to maintain the humidity levels in a new unoccupied house. They return after a week and find the 3 ply laminated floor buckled or shrunk depending on the weather. These are poorly designed floors, and should not be used in a kitchen. Read about this in the Prefinished article, which can be found in the search box at the top of the web page.

Real laminated floors are made from thinner plys of all the same wood (no softwood cores), and are generally 5 plys or more. These are also light duty floors, but are much more moisture stable. The top ply is far too thin to resand in the future. We had a 5-ply 5/16" floor go through 3 floods, and only after the last flood did we have to replace it. But alas these floors have gone out of style and only the 3-ply softwood core engineered wood seems to be available now. And that is typical of the Prefinished floor business, they discontinue models every year, orphaning many people's floors. There is no to turn when only one company makes your floor, and then next year decides not to. Kitchen floors get damaged and need repairs more often that any other floor in your house.

Now the floating floors are not a good idea either, because even though the seams are sealed in this case, it is glued up with a short-lived PVA adhesive. These floors sound a bit hollow and once the glue fails and the pad degrades (10 years) you will have an unfixable floor.

I have revisited some of my kitchen installations after as long as 15 years. The finish is somewhat worn, but the wood can certainly be sanded and finished repeatedly. Up to 6-8 times. But I always use a narrow board. No more than 2 1/4" by 3/4". And if you want really stable wood choose the clear quarter sawn grade of white oak, finished on the back side with 2 coats poly and the top finished on site with 4 coats poly. This Oil Modified Polyurethane has proven itself over my entire 24-year career to be the longest lasting and most water repellant finish. And it ages well. The water based coating are OK, but they are still new, and they are still working on new formulas.

I have seen some of my older water based finishes start to turn opaque white after about 5 years. And I have seen other floors, turn so white that you could no longer tell what type of wood was under the finish. There is a technical reason for this, which as far as I know they haven't sorted out. So for now, I'm holding back on using the water based finishes on my floors, unless I am asked to. And I warn my customers about this opaqueness of the finish.

But the Dura Seal 1000 may come close to being a good finish. Read about Dura Seal 1000 in the article available in the search box at the top of this web page. It is only about as durable as the OMP but can be applied without all the fumes. With this finish you will have to start out with 5 coats. And expect to apply 2 coats every time you recoat because of the low build.

Now as far as the hydronic system, wood floors in general are not the best choice. It simply doesn't have the mass of ceramic and won't hold the heat nearly as well. A 1" plywood subfloor will keep the hardwood isolated from any moisture below. And you will need to keep the heat to no more than 80 F in the pipes. You will have to raise the heat slowly in the Fall and lower it slowly in the Spring. And the real key is to keep the humidity between 40-60% all year round. Museums keep their collections in rooms pegged at 50% humidity and they have no wood movement. You will have to be almost as fussy, if you want no seams to open in this floor.

I frankly wouldn't do wood floor in a kitchen, and never on a hydronic system, it's just defeats the whole concept of thermal mass heating. Keep this opinion in mind, as I am the only one NOT trying to sell you something.

You may also find these articles helpful:

1. Plank Floor: What Special Considerations This Type Of Floor Raises

2. How To Apply Oil Based Polyurethane WITHOUT The Pits And Bubbles

3. Hydronic heating under your wood floors

4. Laquer Finish Floor Fires

5. How To Take Care Of Your Health And Safety when Installing, Finishing, Repairing or Cleaning your wood floors