Type K or L soft copper is permissible when placed __________________ in a partition on remodel only.

The correct answer is that Type K or L soft copper is permissible when placed vertically in a partition during a remodel. This practice adheres to plumbing codes that specify the orientation of piping materials based on safety, accessibility, and performance criteria.

When soft copper is installed vertically in a partition, it ensures that any potential issues, such as condensation or thermal expansion, are managed effectively. Vertical installations also facilitate the natural flow of fluids by taking advantage of gravity, which can help in areas where drainage or venting is involved.

In contrast, installing the copper horizontally may lead to challenges with drainage, especially if there is any significant length of piping, where the risk of water pooling or blocking could be increased. The inverted position is generally not permissible due to concerns with access for maintenance and the same risks associated with horizontal installations, where gravity does not assist in fluid flow.

By adhering to these guidelines regarding the vertical placement of Type K or L soft copper in a partition, practitioners ensure compliance with the plumbing code and contribute to a safer, more reliable plumbing system in remodeled spaces.