Case 1

Cause of Defects

Upon examination of the backing wall from which the plaster has delaminated, a powder coat was noticed. This suggests that the top coat together with the spatterdash coat has come off cleanly from the concrete backing wall.

This could be due to:

1. the background not been given sufficient cleaning preparation. The background is dirty and thus results in a reduction in adhesion of the plaster coating with the background See Figure 1
2. the curing agent has been applied to cater for early stripping of the formwork and have not been sufficiently removed prior to the application of the plaster. This layer of curing agent will reduce the proper adhesion of the plaster to the concrete
3. the plaster work does not have adequate support from the substrate below
4. the correct application technique and handling of the plasterer is important to prevent such defects