Hair line cracks

Q. Why does my installed floor have hair line cracks during the winter and they go away during the summer months?

A. Wood expands and contracts normally to temperature/humidity levels.  The outdoor humidity level directly affects the inside humidity.  When the outside humidity level falls due to dryness in the air, so does the inside humidity level drop.  In turn that causes the wood to react by pulling itself in and a small separation can be noticed between the boards.  This is perfectly normal!

Some wood species have more movement than others and the separation maybe more noticeable than with others. Once the outside humidity starts to rise, that will directly affect the inside humidity, thus causing the wood floor to expand causing any gaps to disappear.  With a newly laid floor we will require the floor to go through one full cycle with regards to changes in temperature/humidity( i.e. one year) before we make any changes to boards that for whatever reason have not reacted to the changes in the environment.