We have an overseas project where the architect wants to use what they call “flexible fire quilts” of mineral fiber insulation, to act as flexible fire-rated dividers in concealed void spaces. They want this rather than gypsum board because of the ease of installation in tight concealed spaces.
Does anyone know of a manufactured product that fits this description? Seems to me it should be more than just a mineral wool blanket attached at the top, but would need some facing or stitching to contain the fibers, and some kind of stiff borders to allow perimeter attachment.
This is not for firestopping of penetrations through fire-rated construction, nor for perimeter firestopping between adjoining fire-rated constructions (as top of wall or slab edge at curtain walls).
Instead it is to subdivide concealed void spaces, similar to firestopping a cavity below flooring. Except they want a flexible not a rigid product.
I am not aware if Thermafiber mineral wool is fire-rated by itself although it does have a Class 1 flame spread (25 or less) and a high melting point (1800-2000 deg F). That only makes it noncombustible.
What are the specific requirements in the governing building code?
Is the code prescriptive- or performance-based or both? In U.S. codes, materials aren’t fire rated, only assemblies.
However, it sounds like they don’t really want a fire-rated material, but more of a noncombustible material to subdivide large, concealed spaces to impede the spread of flames and smoke.
Since I’m only familiar with U.S. building codes, the IBC does allow the use of mineral wool or glass fiber blanket insulation to be used as fireblocking per Section 717.2.1 and as draftstopping pe Section 717.3.1, provided materials are “adequately supported.”
Please post a link directly to “Knauf Insulation Rocksilk Smoke and Fire Barriers.” I have crawled all over the Knauf US web site and cannot locate this brand name. All Knauf’s products appear to be glass fiber versus rock or slag fiber (mineral wool).