For wall coverings using siding, what is the primary purpose of lap joints?

The primary purpose of lap joints in wall coverings using siding is to minimize moisture infiltration. When siding is installed with overlapping joints, water that might penetrate the surface is directed away from the underlying structures. This design ensures that any moisture that does manage to get past the outer layer has a reduced chance of reaching the sheathing and framing, which helps prevent rot, mold, and other moisture-related damage.

The effectiveness of lap joints in guiding water away from the house is crucial for the longevity and integrity of the building. In environments where rain or high humidity is present, this feature becomes especially important to maintain the overall health of the structure. While other factors like aesthetics, cost, and installation ease may also be relevant to siding choices, the fundamental function of lap joints is to provide a strong protective barrier against moisture, thereby safeguarding the building envelope.