Learn about Mineral Wool Batt Insulation

Batt insulation made of mineral wool fibres, literally melted and spun fibres of rock, matted together. The rock is a combination of volcanic basalt and recycled slag, a product of the steel and copper industry. Mineral wool batts are designed to be installed in wall cavities, floors, ceilings, and attic spaces.

R-value measures the insulating ability of materials. The thicker the insulation, the higher the R-value. Mineral wool typically has an R-value of about 4 per inch, so a 2x6 (5 and a half inch) layer gives you R22. Choose the right size and thickness to fit your stud or joist space so that the insulation fits snugly but does not get compressed. Also look for mineral wool that contains a high percentage of recycled material.

A thick layer of mineral wool insulation in your walls and attic can cut your energy bill dramatically by reducing heat transfer between your home and the outdoors. This insulation is durable, highly fire resistant, not damaged by water, and provides good sound dampening.

In 1840, Edward Parry started making mineral wool from the slag waste at a steel mill in Wales, by blowing a jet of steam on the molten slag as it poured out of the mill. He was trying to find something more useful to make with all this slag, and it worked only too well. It produced great huge drifts of mineral wool that blew all over the steel yard in the wind and got in everyone's way, making Eddie not the most popular fellow in the yard. Luckily for him, they eventually figured out how to make it into insulation!