Laying Topflor Step 6 And now proceed row for row. Remove the excess glue after the first setting (some 15 minutes) with a plastic trowel. Simply wipe off the remaining glue with a damp cloth. Measure the exact width for the last row of panels. To do so, lay a panel on the second to last row. Then lay a second panel with the tongue to the wall on top of the panel to be measured and use the ruler. Please do not forget the gap to the wall! Saw the panel along the marking, and carefully fit it using the draw knife. Next - Possible Problem Areas