Floor System Performance: a Matter of Perception

OPEN JOIST floor trusses are engineered for superior strength...strength that can be used to achieve optimum floor system performance or maximize floor framing efficiencies.

It should be recognized that floor system performance is a very subjective issue for those who occupy a structure. One person’s opinion of how a floor should “feel” can differ markedly from that of another person. And, industry standards aren’t necessarily helpful...meeting minimum building code requirements does not always result in end-user satisfaction.

The two most common performance factors that influence an individual’s opinion of a floor system are deflection (bending) and vibration. United States model building codes restrict the amount of deflection under load permitted in floor systems but U.S. codes do not prescribe vibration standards.

When designing and installing a floor system, consideration should be given to the following practices and conditions that have direct effects on floor deflection and floor system vibration:

Proper installation of “Strongback Bridging” within the floor system will help to restrict deflection and, most important, dampen floor system vibration.

Deeper floor trusses will reduce deflection and vibration.

Reducing on-center spacing of floor trusses will reduce decking deflection.

Thicker floor decking will improve load sharing and help reduce deflection.

Installing floor decking on floor trusses using both adhesive and fasteners will improve floor stiffness and help prevent squeaks. Screws are more effective fasteners than nails.

Framed partition walls and other permanent dead load components will dampen vibrations. Wall plates should be fastened through decking into floor joists.

In an effort to satisfy floor system end-users who carry heightened perceptions and expectations, consideration should be given to the preceding factors when designing floor systems.