Warning: Familiar flatness specifications are dangerous to your company’s health

For years contractors regularly produced out-of-spec floors because owners hadn’t really needed their floors to be as flat as they were specifying. Extreme flatness was desirable but for the most part nonessential. Now, however, technology in warehouses and factories has resulted in the high-rise, narrow-aisle lift truck that simply will not function properly on an unflat floor. Nor is the problem limited to warehouses and slabs-on-grade. High-rise office buildings, for example, are now employing modular, relocatable partition systems which require that clearances between ceiling and floor be maintained within strict limits or the walls cannot be installed as designed.

What, then, is a contractor supposed to do? On the one hand he has an accepted, recognized, standard flatness specification. But in the context of current acceptable construction practices this specification is unrealistically tight. On the other hand he is faced with an owner who is now able to measure and enforce this unrealistic specification rigorously.

Clearly, any contractor who decides to avoid the problem by bidding only those projects with realistic flatness specifications will soon find himself not bidding any work at all. To protect himself against the possibility of a downstream disaster, the concrete contractor should now undertake specific actions on every floor project. These include: Review in detail the exact meaning of the flatness specification and seek to change any unrealistic tolerance requirements; if the architect or owner will not change the specification, seek to amend the specification so that it establishes some acceptable reference floor as a standard (this should preferably be one which your company installed); always place a test slab; and, insist upon timely inspection of completed work.