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Interior Finish

Structural Deterioration And Damage

Problem: Wavy ceilings.

Cause: High humidity and water absorption by ceiling drywall.

Water-based finishes are often applied to the ceiling and if the drywall absorbs a substantial amount of this water, it can sag as shown in Figure 27. Textured ceilings are common examples.

Wet Drywall Sags Between Truss/Rafter Supports

Figure 27 - Wet Drywall Sags Between Truss/Rafter Supports

Solutions: Use thicker drywall.

  • Heavier drywall is better able to support itself and the insulation above in elevated moisture conditions. Most building codes require that 5/8 inch (16 mm) gypsum board (drywall) be used for water-based textured ceilings when supports are 24 inches (600 mm) o.c. Apply the drywall perpendicular to the supports.
  • You may use controlled-density (CD) or sag-resistant (SR) drywall in place of regular gypsum board.

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