Flooring installers need to
measure fl atness with a
straightedge that crosses
construction joints, column
blockouts, and near
penetrations. F-numbers
measured in accordance
with ASTM E1155 will not
yield this information. The
top photo shows a
carpenter’s level placed
across a construction joint
and the bottom photo
shows a straightedge being
used to check fl atness at a
column blockout.
