Draft stopping is material installed to subdivide large concealed spaces, like extensive attics or large floor-ceiling assemblies, into smaller compartments, limiting how far fire and smoke can travel through these bigger hidden areas compared to leaving them as one continuous open space.
While fire blocking addresses smaller cavities within individual wall or floor assemblies, draft stopping addresses the larger-scale concealed spaces that can exist above ceilings or within larger structural assemblies.
Building codes typically specify maximum allowable area for a concealed space before draft stopping becomes required, reflecting the increased fire risk larger unbroken spaces present compared to smaller, naturally compartmentalized ones.
What Does Draft Stopping Involve?
- Gypsum board or similar fire-resistant material
- Subdivision of large attic or floor-ceiling spaces
- Placement based on code-specified maximum area limits
- Coordination with the overall building’s fire safety design
Why Is Draft Stopping Important?
Large, unbroken concealed spaces allow fire and smoke to spread rapidly across significant distances within a building, potentially compromising escape routes in areas far from where a fire actually started. Draft stopping limits this rapid, large-scale spread, giving occupants more time to safely evacuate and firefighters a more contained situation to address.
This requirement typically becomes relevant in larger residential buildings, like sizeable multi-family structures, more often than in smaller single-family homes, where concealed spaces are less likely to exceed the code thresholds triggering the requirement. Consulting local code requirements early in the design of a larger structure helps ensure this detail isn’t overlooked. This early attention avoids costly compliance issues later in the project.
Draft Stopping vs. Fire Blocking
Draft stopping subdivides larger concealed spaces, like extensive attics, into smaller compartments. Fire blocking addresses smaller individual cavities within specific wall or floor assemblies, and both work together as part of a building’s overall fire safety strategy at different scales.