What is the MINIMUM joint width of butt-joint glazing?

Butt-joint glazing is a method where two adjacent glass panels are joined at their edges, typically without visible framing. The minimum joint width is critical for accommodating thermal movements, ensuring proper sealant application, and allowing for the expansion and contraction of the materials involved due to temperature fluctuations.

A minimum joint width of 3/8 inch is specified to provide enough space for these factors, minimizing the risk of stress on the glass and the failure of seals. This dimension helps to maintain the structural integrity of the glazing system, ensuring that it can withstand external forces such as wind loads and impacts. Furthermore, it allows for sufficient sealant coverage, which is essential for preventing water ingress and ensuring the longevity of the installation.

The other choices represent dimensions that are either too small to accommodate the necessary movements or too large, which could lead to aesthetic concerns and may not provide any functional benefits. Therefore, the selection of 3/8 inch as the minimum joint width ensures that the installation remains effective, durable, and visually appealing.