Where the floor meets the house there should be an expansion gap about 1/8-inch wide.

To allow for these changes, it is necessary to leave an expansion gap equal to the wood's thickness around the perimeter of the floor.

The easiest way to nail this shingle is by driving a nail through the expansion gaps (one nail in each gap) in the overlapping shingles.

In addition, if rails were allowed to creep, it was always possible that several successive joints closed up, so that the expansion gap was lost, with inevitable results at the onset of hot weather.