Jeff continues his discussion on the errors that can happen in estimating.

This month, we continue our ongoing discussion of mistakes made in the estimating process, and the ways and means by which they can be eliminated and minimized. Our topic of discussion this month concerns one of the most frequent mistakes: oversights. In estimating parlance, it is the first deadly sin—the sin of omission.

A cut above

For an estimator, working in the New York City construction industry is kind of like being a test pilot—you get to fly every type and size of airplane. And, like the test pilot whose skills are sharpened by the variety of experiences he has, so too has my experience been multiplied by the wide variety of building types and sizes the city has to offer. This experience has taught me not to take anything for granted and that, like people, each and every job has a personality and a specific level of complexity. Like the test pilot who must be “a cut above” the average pilot, so too must my peers and I be a cut above the average estimator to deal with the sheer variety, scope and complexity of the projects the Big Apple has to offer.

Ignorance is never bliss

At the time of this writing, I am working on just the just the kind of project that separates the men from the boys: an addition to an existing museum in lower Manhattan. By their very nature, museums are atypical and complex structures—this one is no exception, with a level of complexity that is quite high. Not only is the interface between the new and existing buildings intricate and detailed, so too is the new structure with curved walls, mixed curtain wall and pre-cast panels at the exterior fa¿e and many high atrium spaces. To deal with this complexity, I must take an unorthodox approach. Rather than deal with the straightforward walls first—by type on the floor plans—for my quantity survey, I am dealing with the detailed, complex conditions first.

Normally, I would save these items for last on a typical project but there is a method to my madness in this case. The fishing expedition I have embarked upon allows me to get familiar with the building, its subtleties and nuances, ultimately allowing me to be confident that my quantity survey is comprehensive and complete when all is said and done. This approach allows the building to define itself, by detail and condition. It is, in effect, the path of least resistance. Anything that affects production and contributes to cost, whether as an ancillary cost item pertaining to the wall types or specific conditions, must be identified and dealt with separately in the quantity survey and cost analysis. To do otherwise would be self-defeating; for it would ignore those items of cost that are an inherent part of any given project and reflective of the true cost; it would be an oversight of the most pervasive kind. When it comes to items of cost, ignorance is never bliss.

This museum project presents a myriad of conditions affecting both the wall and fascia/soffit/ceiling assemblies, in general and specifically. A good example of an ancillary cost item affecting all wall types is the “Head-of-Wall” condition. The wall type schedule only shows the wall types in plan-detail—there is no “head” depiction (in section-detail, along with “base” and “plan” sectional views as is most common). It is a typical requirement for the walls to allow in their design the ability to deflect due to lateral movement—particularly in seismic zones (that includes Manhattan Island) and provide a smoke/fire barrier at the interface between the underside of the deck and the top of the wall. Knowing this, I checked the drywall specification and, as I suspected, it defined the slip-joint and fire-safety requirements at the head-of-wall. Had I not checked the specification, it would have been quite easy to overlook this important ancillary assembly condition. Experience being the best teacher, I know to look for it instinctively.

Other examples of ancillary cost items to watch out for include, but are not limited to the following:

• In-wall grounds

• Cut-outs

• Patch and repair

• WR/MR GWB at ceramic tile

• TBB/CBB at shower/bathtub surrounds

• Abuse-resistant GWB

• Finish levels for tape and spackle

• Beads

• Control/expansion joints

• Wood blocking within walls

• Bracing requirements

• Wall terminus/mullion conditions

• Window head/sill/jamb conditions

• Gauge/spacing requirements

• Limiting height criteria

• Safing at floor/wall penetrations

• Safing at elevator door frames

• Framed/trimmed openings

• M/E/P penetrations

• Caulking

• Deck/beam plates

• Shims

• Fireproofing removal/repair

• Vapor barrier at exterior/perimeter walls

• Sound/vibration components

All of these general ancillary cost items have labor and material costs associated with them. I’ve known estimators who ignore one, some or all of these items of ancillary cost. This is their prerogative. For me, to do so violates my golden rule of estimating: “If it costs money, whether real or imagined, it must be identified, quantified and analyzed for cost.”

Next month, in Part 8 of our mistake making discussion, we’ll examine those specific conditions that need to be considered lest we commit the deadly sin of omission/oversight in our estimates. W&C