Where Should Sampling Occur?
The first consideration is where should the sampling take place? In northern latitudes, a southern exposure is an obvious first location to sample, with the converse logic applying in southern latitudes. This allows the sampling to occur where the greatest thermal joint movement takes place.
The next best place to sample is the “weather side” of the building. The reason for this is that difficulties during construction in obtaining dry substrates to apply sealant tend to be on the weather side. However, at times the difficulties may occur on the “dark” (shaded) side of the building where there may be a reduced ability for the substrate to dry out.
FIG. 2—Weather side of a building not much affected by moisture problems (“Specimen A").
Of course, historically verifiable problem areas take first place in order of importance. Without historical data, the tester must take many thoughtful considerations into account when deciding on sampling locations. Dictating this is not appropriate here or in any document due to the uniqueness of every building both in its construction and circumstance. As an example, Fig. 2 shows a building where the weather side was not as much affected by moisture problems as the “dark” (shaded) side since on the weather side the joints were able to dry out. This building facade side is considered “Specimen A” for the subsequent discussion.