Tuesday, July 28th, 2015

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Floor Levelness of Elevated Floors: Considerations in Design

by Jared O.W. Lewis

Gravity happens; all of the time.  It effects everything from the flight path of a golf ball to the deflection of structural framing.  It’s safe to say that it effects everything we do for the built environment.

As engineers, we compensate for the effects of gravity by choosing appropriate building materials and structural member sizes.  And for many structures, a design that adequately supports the forces of gravity without failure meets a functional standard of care and need not be analyzed further.  But, this approach ignores the effects gravity has on the space we use.  Often, it’s not enough to design the structure to merely be strong enough to resist the forces of gravity.  Commonly, the design of the elevated floor structure is governed by the levelness of the finished floor.

The engineers at catena understand that floor levelness in elevated structures is more art than science.  We rely upon our experience and judgment to provide our best recommendation for the structural makeup of the building and upon distinct specification language to control the construction and measurement of the level floor.  We know that a level floor meeting the specified minimum FL value of 20, works for an open office environment; it does not satisfy the needs of the users of a film studio or high tech manufacturing facility.  We also know that increasing the structure to compensate for the vertical deflection due to gravity is not economically feasible.

At the recently opened Kaiser Westside Medical Center in Hillsboro, Oregon, floor levelness was paramount for the functionality of the hospital and medical office building.  We worked hand-in-hand with the owner and contractor and shared anticipated floor deflections and the requirements of the specifications were measured.  By working closely with the entire team and by working transparently with the contractor so they understood the effects of gravity on the design of the elevated floor structure, our efforts in design worked in tandem with the team to deliver level floors for our client.

In my next post, we’ll delve into the details of floor levelness requirements for different types of programming needs and some ideas for working with your design team to achieve the programming objectives.

Image Credit: Eckert & Eckert Photography

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