How to install raised access floor

STEP 1. Check the room dimensions and configuration against approved drawings. Using a builder's transit or laser, shoot in the areas to receive access floor to determine how much variation there is in the level of the subfloor within the room and at the termination points, such as elevator and door sills and concrete ledges.  If the floor cannot be installed per your drawings, notify the general contractor superintendent for agreement on corrective action.  The FFH may have to be changed.

STEP 2. Find the starting point in the room. Seek approval to change the starting point if cut panels at the perimeter will be too small to allow proper support. Recommended minimum size of the cut panels for proper support is 6 inches wide.

STEP 3. Having established the proper starting point, lay out two chalk lines at right angles to make sure the room is square. Chalk lines must be used as control lines for installing the access floor. The reason for laying chalk lines for installing the access floor. The reason for laying chalk lines rather than just measuring from the walls is that the walls are not always square. The chalk line system gives a square reference point. Be careful to keep the access floor square at all times during installation.

STEP 4. Chalk the two control lines and spread pedestal assemblies in an area approximately 48 feet x 24 feet, making sure to start at the approved starting point.

STEP 5.  Using a laser or transit, shoot in a pedestal assembly to the proper FFH every 8 or 10 feet in both directions (depending on the length of your leveling bar.)  By spanning two pedestals at proper FFH with the leveling bar, adjust all the pedestals in between to the bottom surface of the bar.  As you adjust each pedestal assembly, center it on the two-foot marks permanently marked on the bar.

STEP 6. Glue each pedestal base in the spread area to the subfloor. Using a spatula type device, tilt up base plate without changing its location and apply adhesive to bottom of base plate.

STEP 7. If stringers are a part of the system, bolt them to the pedestal heads beginning at the starting point.

STEP 8. Beginning again at the start point, lay four rows of panels along the longest wall. Check to see that you are staying on control lines, and that panels do not rock.

STEP 9. If an panel rocks diagonally when placed in the system, turn it one quarter (90°) turn and check it again. If the panel continues to rock when rotated, some debris may be between the panel bottom and the pedestal head or stringer. Also check to make sure pedestal is not tilted, stringers are properly seated and that panel edges are flush. If the panel still rocks, set it aside to be used as perimeter cut panel. The pedestals should not be adjusted unless three or four panels supported on it are rocking. At this point, make a minor elevation adjustment to the pedestal.

STEP 10. After laying the first four rows of panels along the long wall, begin again at the starting point and lay four rows of panels perpendicular to the first rows. Follow the same previous steps (8 through 9) for laying panels and be sure to follow the control lines.  If you do not stay on the control lines, the floor will not be square and your grid lines will not be straight.  After laying in the ELL section, check and re-check to be sure it is square.  When you are certain the ELL is square, continue to install rows until the ELL becomes a rectangle or square. While you are laying panels in this area, you should have someone spreading, shooting, leveling and preparing the next adjacent area for panels.

STEP 11. After the first section of a floor is installed, check to see that all the grid lines are straight. If the grid is not square, you can make them square by bumping the rows of installed panel with your foot. If this fails, take up every third or fourth row of panels and tap the bases in the direction of the panels that have to be moved. All grid lines should be straight before cutting in the perimeter panels.

STEP 12. After installing the first section of A/F, only one chalked control line along the long wall needs to be used for the remainder of the floor. The initial section of floor normally dictates the squareness and location of the rest of the floor. However, it is possible in a long room to allow a curve to develop in small increments in the grid. Therefore, a dry line should be kept stretched along the short wall until at least a four-panel-wide section of the floor is installed the entire length of the room.

In setting this dry line, secure one end at the starting point on the grid line between the first two panels. Raise the line about one inch off the panel, then stretch the line to the other end of the floor and do the same there. The line should not override the panel edges.