Inverted Deck Roof

An inverted roof is quite simply where the waterproofing layer is installed over the structural deck rather than over the insulation.

Inverted deck roof.

Inverted n dek acoustical is a 3 inch deep wide rib inverted acoustical structural roof deck unit that provides a support surface for various types of roofing materials. This makes it the only material suitable and approved for inverted roof applications. Inverted roofs have significantly lower maintenance costs than conventional low slope roofs thanks in large part to the insulation in the inverted assembly protecting the roof membrane from mechanical damage during and after construction as well as temperature extremes that cause stress. When the insulation was removed from the worst affected area a large number of water filled blisters were found in the waterproof membrane figure 1.

Rigid extruded polystyrene insulation has minimal water absorption due to its closed cell structure. Problems can occur if the accumulation of condensation persists. For more information see specifying insulation for inverted roofs. Inverted n dek is the 3 inch n dek profile placed in the inverted position for a unique ceiling aesthetic that provides a smooth ceiling appearance with heavy shadow lines.

For a case study of an inverted roof defect see inverted roof defect case study.