Floor / Ceiling Sag

Common Terms:

  • Uniform Load: Force evenly distributed over a relatively large area (i.e. a waterbed).
  • Concentrated (Point) Load: Force localized over a relatively small area (i.e. a load-bearing post or a woman’s spike-heel shoe).
  • Dead Load: Weight of permanent components such as roofs, walls, floor, etc.
  • Live Load: Loads superimposed by use and occupancy such as people, furniture, etc.

Common Problems:

  • Improper design does not account for all load the floor must support.
  • Improper construction that increases span of framing or decreases size of framing members.
  • User applies more load than anticipated for type of occupancy.
  • Structural weakening by wood rot due to water intrusion and ponding.

Potential Damage:

  • Ponding of water on exterior surfaces such as balconies or roofs.
  • Cracking of finishes such as stucco or gypsum board.
  • Walking surface excessively sloped and springy.
  • Squeaking floors.

Typical Solutions:

  • Add full-depth blocking between framing members to help spread out concentrated loads to adjacent members (does not help for uniform loads).
  • Add additional framing members to reduce the amount of load to each member.
  • Provide additional points of support beneath the floor to reduce the span.