Which defensive strip variant is performed off beam?

• A. A hose line
• B. Defensive Strip With Construction (Off Beam)
• C. Defensive Strip (LWP Roof Diagram)
• D. Defensive Strip Against Construction (Off Purlin)

Answer: (B)

In vertical ventilation, a defensive strip is a controlled roof cut aimed at venting heat and smoke while protecting exposed areas. The location relative to the roof structure matters: off beam means you perform the strip away from the main roof beams, using the space between or alongside the beam line, often guided by construction features to keep the opening safe and effective.

The variant that matches “performed off beam” is the one described as Defensive Strip With Construction (Off Beam). The wording itself signals that the cut is made off the beam and uses construction elements to guide or support the operation, which is exactly what the question asks. The other options either refer to different locations (off purlin), a different diagram context (LWP Roof Diagram), or a method not described as an off-beam defensive strip (a hose line).