Fire-resistive joint protection at the bottom of rated wall assemblies plays a critical role in maintaining effective compartmentation and life safety within buildings. While these intersections are sometimes assumed to be static conditions, real-world construction tolerances, building movement, and system interactions can create gaps that allow the passage of fire, smoke, and superheated gases if left unprotected. Decades of fire testing and field experience have consistently shown that unprotected bottom-of-wall conditions do not meet required fire-resistance and air leakage performance criteria. Properly designed and installed fire-resistive joint systems at these locations are essential to preserving the integrity of rated assemblies and ensuring that buildings perform as intended under fire conditions.

To demonstrate the importance of bottom-of-wall systems the International Firestop Council conducted a series of nineteen tests in five different test and research laboratories. The results illustrate that protected joint systems consistently outperformed unprotected bottom-of-wall joints by a wide margin. Testing showed that protected joints provide the level of safety required by codes whereas unprotected bottom-of-wall joints do not. The testing also confirmed static bottom-of-wall conditions require a protected joint. This research illustrates how inadequate protection of bottom-of-wall joints severely impacts the intended fire performance of a compartment, reducing passive fire protection and allowing an unprotected path of fire and smoke spread between compartments.

The white paper, full test report, and all other supporting documentation are included below.

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