Tom Tedford makes a living installing underlayments for concrete floors in the Phoenix area. As a pro, he knows how cumbersome the leveling process can be for large projects.
The problem was severe when the hardened concrete surface was wavy. Often placing contractors, knowing that the floor was to be topped, left a surface with several high and lows. In many circumstances, the high spots were near joints and low in the sections’ center. Tedford often found this elevation problem on high-rises when, after the concrete dried, the suspended floor became uneven.
In his prepour routine, Tedford would first sand and then prime the floor surface. He then would chalk perpendicular lines using a 3x3-foot, or 2x2-foot grid pattern. At each line intersection he then set a series of self-adhesive plastic tabs.
Using a target benchmark as reference, Tedford’s crew would first measure the elevation at each point. Before he would affix a series of little plastic tabs to the floor he would have to measure that portion of the surface. One person would take the elevation reading and the other would have to trim the tab by hand to the proper target fill height. "If the mark was a half-inch low, a placer would take a pair of scissors and trim the tab to a half-inch length," he says.
The process was accurate and it always worked. But there was one big drawback. "Floor prep was horribly time-consuming," says Tedford. "I went out on job after job and thought, 'Gosh, it takes half a day just to put the tabs on the floor for a 20,000- or 30,000-squarefoot floor.'"
As many people do when they get fed up, Tedford started to think of a faster process to measure a concrete floor’s levelness. What he devised is the AccuraTab floor leveling system.
The trimming machine Tedford developed has a blade that is positioned on a carriage with a hand crank. The operator cranks the crank while the sled travels up and down on two rails. On the bottom of the sled is a pipe and a pair of pinchers that hang down.
A laser target is mounted on top of the machine. The operator first locates the floor’s high point. He then positions the trimming blade to the elevation that accounts for the minimum floor underlayment thickness as specified by the contract. This, in turn, establishes the laser target’s elevation.
A single operator then rolls the machine over each tab. The operator adjusts the trim blade based on the laser’s reading. One hand crank adjusts the trim blade’s elevation by 1/8-inch. The laser emits a beep signal when the target is level, alerting the operator to squeeze a hydraulic lever. This sends hydraulic fluid down to a cylinder, which then pinches the pinchers together. A utility blade slices through the tabs which are all trimmed to the same level.
"You can effectively take a 6-foot level and put it across any two tabs anywhere in the room and it’s going to be level," says Tedford. "Then you pump your selfleveling underlayment to the top of the tabs. It saves time and money, and turns it from a two-man operation into a one-man operation."
The AccuraTab system has a custom tab which is designed with metric measurements on one side and English on the other. A new round tab is coming out in March which will have no increments on it. "The trimmer doesn’t need increments," says Tedford. "The increments are put on for hand-trimming."
Depending on the size of the grid, one person can use the system to complete a 20,000-square-foot floor in five or six hours. Tedford introduced his system at World of Concrete. He is targeting a price of $3800.
Altimeter for leveling
The AccuraTab system can have an innovative add-on. Rather than investing in a laser level, operators can use a precision altimeter to trim the floor-leveling tabs.
Unlike rotary lasers, the ZIPLEVEL lets one person read elevations directly in digits. The unit also makes it easier to work in rooms with restricted sightlines. Created by Technidea Corp. of Escondido, Calif., the device can measure elevation differentials without the tilted level plane error common to lasers. The device is reported to have 0.05-inch precision.
Contractors have requested accessories to make the tool more efficient in floor surface applications. So the manufacturer has also developed a line of floor leveling accessories. ZIPLEVEL Tab-Trim products both set tabs and then use the built-in intelligence on the ZIPLEVEL to manually or automatically set trim heights and trim tabs while calculating an estimate of material required.
A $199 Tab-set device secures self-adhesive plastic leveling tabs without the operator having the bend over. The ZIPLEVEL Measurement Module is attached to either the $1299 manual or $1999 auto tab trimmer and zeroes in above the highest area of the floor to set the level where the tabs should be trimmed.
Both the AccuraTab and ZIPLEVEL were entered in the Most Innovative Products contest at World of Concrete. You can still vote for either at www.mip2010.com.