When installing a natural wood floor in your home don't forget the importance of Acclimatising all timber flooring beforehand. This is to allow the moisture content of the wood to adjust to "normal living conditions" at the site with normal temperature and humidity conditions that will be experienced once the building is occupied.

How to Acclimatise Wooden Flooring

Solid wood flooring should be delivered to the job site and allowed to acclimate to the conditions in which it will be installed or near occupancy levels. Temperature and humidity should be monitored. Typically a minimum of 14 days should be allowed for flooring to acclimatise properly  - this may mean running the heating during the acclimatising period.
If in doubt add a couple of days before installation - better safe than sorry!

Delivery should take place after major projects have been completed and the building is thoroughly dry - especially dry wall and masonry work.

Doors and windows must be in.

Testing of wood sub floors should be performed and moisture levels should not exceed 12-14%

Reclaimed pitch pine floor boards, parquet and especially wide board oak floors need to be given time to adjust to a new environment before they are installed.
Drainage is critical. To avoid problems like floorboards "cupping" or warping, it is vital that moisture be directed away from the floor to prevent damage to the floor.

Basements and indeed all rooms with a solid wood floor need proper ventilation.

A Polyethylene moisture barrier of suitable thickness must be used in any project where the foundation lies underneath the wood floor.

By following these steps your floor will remain perfectly flat for years to come.