Hickory floor cupping

Q: When I moved into my house 1 1/2 years ago I had carpet and ceramic floors removed and new hickory prefinished hardwood put in my entire downstairs. Almost immediately my floors started cupping, some areas are raised and some have vertical cracks in the wood. You can feel when you walk over and it’s on over 50% of floor.

The installer and manufacturer salesman came out, agreed it was cupped and said it was caused by humidity. However every time they have taken readings it is always normal. I have a dehumidifier running 24/7 and humidity ranges between 35 and 40%. Our house was inspected before we moved in, we have a new roof and new A/C and our crawl space has no signs of moisture and has moisture pad on crawl space floors.

Could there be another reason besides moisture why the floor is cupping? It sat in my house for 2 weeks before installation. We paid a lot of money for them and we are not satisfied with the look of them. Could there have been a problem when it was milled?

A: Everything sounds like it is being done correctly. Humidity levels in the home are good. Yet the wood itself seems to be showing an imbalance in moisture. Cupping with raised board edges indicates the moisture is coming from under the board and working it’s way up. If the issue was from the top, such as a significant spill on the floor surface you would more than likely end up with crowning, where the center of the boards are raised. In Canada I’ve not had occasion to work with hickory though I know it is very hard wood, the hardest north American species and is rather sensitive to any environmental changes. The wider the hickory plank the more pronounced such changes would be. I doubt there would be an issue from the mill. They dry the boards to required specs. Then they run them through planers and shapers to create the tongue and groove then stain/finish. If all conditions are as you have described with no high moisture readings in the crawl space perhaps it is just the species of wood. Did anyone check the crawl space and put a meter on the subfloor which this hickory is sitting on? When they installed the floor, did they use some type of underlay such as roofing paper to retard moisture movement? This does not prevent moisture movement but slows it down.

Hickory floor starting to cup and bow

Q: We have a hickory floor that was installed seven years ago and through time the floor is starting to cup in spots and bow in others. It has become very creaky in certain areas. The main areas of concern are near the front door and a transition to another flooring type. We control the relative humidity in the house between 40-50% and temp around 70F. I have taken pin less moisture content readings on the hardwood and it is averaging 8%, while the subfloor from underneath averages 10%. From what I can tell the amount of moisture doesn’t seem to be excessive; what else would cause these issues? What is the best approach to tightening up the creaky floor? Could this have been from a bad install where they didn’t secure with enough nails?

A: Cupping is caused by excess or an imbalance of moisture moving through the wood from beneath.  Crowning is caused by the same thing but from above.  Hickory isn’t that common in Canada but from all I’ve read, besides it being very hard is rather cranky and tends to over react when there is a moisture change.  Very hard wood is susceptible to this.  Splitting also.  How is your floor as far as gaps between the boards?  What was the floor installed on top of?  Creaking means the wood is moving and that is the sound of two boards rubbing together.  I would take some readings not just from the trouble areas but all over.

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