Coefficient of thermal expansion

The wood around the hearth is ash flooring with the grain perpendicular to the floor. I never accounted for expansion and contraction and as the wood expanded it pulled the nails out and pushed the wood away from the corners.






This probably shows the problem the best. I reinstalled the wood but the corners are only about an inch on each side with a 3/8" gap to the main run on each side (forgot to take a pic). I will then put a piece of 1/2" by 1 1/2" piece on each side which will allow the main run to expand.




My breakfast bar also seems to be affected but to a lessor extent.