Mineral Fiber Product description

Although the term mineral fiber historically refers to rock wool and slag wool, fiberglass products are also included in this cate­gory. These are also called man-made vitreous fibers (MMVFs), referring to the glassy, noncrystalline nature of these materials. A binding agent helps form the fibers into a rigid insulation board to be used for low-slope roofing systems. A glass-mat facer is applied to the top surface of the board. Mineral fiber insulation is compat­ible with bitumens and other adhesives, fire-resistant, dimension – ally stable, and compatible with other roofing materials. Mineral fiber insulation is not as sensitive to moisture as fiberglass insu­lation because the separate mineral fibers absorb (but retain) only minimal moisture.

Fiberglass insulation board is a slightly modified product. After bonding fiberglass into a board shape, asphalt is used to bond a kraft paper facer to the top surface of the board. The paper facer will deteriorate if wetted, and the fiberglass board will retain water, reducing the thermal value.

The thermal resistance of mineral fiber is stable and has a rela­tively high R-value compared with other insulation materials. Mineral fiber board has a low compressive strength and is not rec­ommended for loose-laid, ballasted roofing systems or mechanical­ly fastened roofing membranes.4