Last month's column described how a preemptive warranty can be used by a contractor to limit risk with regard to the principal uncertainties associated with concrete floor construction: cracking, curling, joint instability, delamination, spalling, sweating, filler failure, Division 9 incompatibilities, inconsistent cosmetics, and vapor transmission.

After my father Sam and I started our super-flat floor consulting business back in the late '70s, it didn't take long for me to run afoul of my first pompous engineer. We had been employed by an owner to critique a slab design, train the contractor, monitor results daily with our profileograph, manage any corrective grinding, and ultimately certify each aisle's flatness and levelness to the lift truck supplier.

Though the warehouse was unexceptional in regards to floor loadings and base condition, the engineer had detailed a 10-inch slab reinforced with top and bottom mats of #6 bars on 12-inch centers. Because a 6-inch slab with a single, unidirectional, topside mat of #5s was more than adequate, I dutifully sent the owner a short letter suggesting he could obtain equivalent performance using this much less expensive alternative. The engineer's office was in Boston, but we could hear the eruption 400 miles away in Norfolk, Va.

Within a day, I was summoned north to be confronted by more than a dozen PEs around a conference table who spent the next hour telling me—in front of our mutual client—how much they knew about structural engineering, how offended they were by my impudence, and how they would "wash their hands of all responsibility for the floor" if any of the changes I had proposed were adopted. Thoroughly intimidated by this ominous declaration, I rushed to apologize. Almost immediately, however, I was struck by one of those sublime "Hey, wait a minute ..." insights, and I asked:

"Exactly what are you going to guarantee about the floor's performance?"

Now sometime during the next minute or so of confused looks and awkward silence, the seriousness of their "we won't take responsibility" threat evaporated. At that moment, the inherent absurdity of the engineer's traditional role in slab-on-grade design was laid bare.

Structural engineers, you see, are essentially barologists whose careers focus on preventing things from falling down. Fundamentally, they get paid to guarantee against collapse. But slabs-on-grade don't collapse, and they certainly don't pose a threat to life or limb. Indeed, their so-called failures involve relatively minor nuisance issues (e.g. cracking, curling, etc.) that fall well outside an engineer's normal sense of professional liability. Nonetheless, absent the builder's misfeasance or nonfeasance, equity requires the party defining the construction to be the party held principally responsible for its functionality.

But slabs-on-grade are the red-headed step-children of the construction industry. When they disappoint, their subjective standards of acceptance and the owners' very poor understanding of defect causation always have allowed the engineer to focus everyone's attention on the construction history rather than on his design.

Previous columns have described various tactics the contractor can use to try to bring a faulty slab design into conformity with the owner's performance expectations. If these efforts fail, however, and the engineer remains uneducable, then—as a final resort—his warranty charade will have to be exposed.

Rule No. 5: If the engineer refuses to incorporate the design changes required to ensure the floor's success, then prior to the initial slab placement, submit an RFI demanding a copy of the engineer's floor warranty.

Then it will be your turn to wait for the eruption.