On Thu, 16 Jul 2015 14:37:44 -0700, "tony944" wrote:

if your floor is 2" thick well you need
2" screw but if your floor is only 3/4 then you need 3/4" screw.

Please explain how the screws fasten to the joist when the length only
matches thickness of the flooring.

The object is to stop "squeaky" floors.