My kitchen floor becomes uneven, develops a "hump", especially during the winter. What is the cause and how may I correct it?

Asked by Ruth
Tucker, GA

The home is a ranch over a basement and the kitchen is over the HVAC unit. I would like to replace the floor covering with hardwood or ceramic tile.


Lucas Johnson

Answered by Lucas Johnson

Seattle, WA

Cascadia Consulting Group

June 18, 2013

There are many factors that can influence the movement of flooring; however, changes in temperature and moisture are most likely the primary driver.

  • If the subfloor is currently uninsulated and not air sealed, then the floor is going to be exposed to much more dramatic changes in temperature.
  • However, the typical subfloor air sealing process will most likely not solve the moisture content issue.

The large majority of moisture entering a home typically comes up through holes in the floor due to "convective air flow." By air sealing these holes, you will dramatically reduce the amount of moisture entering your home, thus lowering the ambient relative humidity indoors.

However, this could mean more moisture trapped below the subfloor, which could lead to further buckling of your floor.

  • To solve this, you will need to determine where the moisture is coming from, and most likely put down some sort of vapor barrier.
  • The good news is that by air sealing and insulating your subfloor, as well as putting down a vapor barrier, you will also make your home a lot more comfortable, durable, and healthier.

I'd highly recommend having a professional "home performance auditor" come take a look, and ideally, combine the auditor's visit with a flooring company visit so they can discuss the issues together.


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