Insulation from mineral wool, or thin strands made from stretching molten minerals, would be as foreign to our ancestors as their stuffing walls with dried seaweed is to us. To think that the byproduct of common stones under our feet would keep our homes warm is a stretch for almost anyone's imagination. It's almost like wanting to full the wall cavities of homes with aluminum tinsel.
However, whatever preconditions have been placed on the material, mineral wool insulation is one of the fastest-growing methods of keeping our homes warm in winter and cool in the summer.
What is Mineral Wool?
How Mineral Wool is Made
Mineral wool and other rock-based insulation is manufactured by heating minerals and filler materials to about 2900°F (which is about 1600°C) in a special furnace. During this heating process a stream of air or, in some cases, steam is blown in under pressure. In more advanced production facilities the molten rock is rotated at high speeds in a spinning cylinder much like the way that cotton candy is formed. What results is a very fine, intertwined fibers held together with bonding agent like starch. To prevent the formation of dust oil is also added during production phase.
Mineral Wool Slows Heat Transfer
Much like fiberglass batts, mineral wool's density traps air in its bulk preventing the transference of heat either into the home or leaving it. Like all rock material the single fibers of mineral wool insulation are not great insulators. In fact they very good conductors of heat as metal or glass. However, when bound together this batt becomes highly-efficient at preventing heat transfer.
In fact, mineral wool is so efficient that it is used to prevent the spread of fire in buildings. This function, and the fact that mineral wool has an extremely high melting point, makes it almost twice as safe as fiberglass, a product that melts at a much lower temperature and lets smoke pass through its fibers.
Mineral wool Versus Fiberglass Batts
When comparing mineral wool to fiberglass it is important to know what will be the end use of the insulating material. However, in a rough comparison:
1. Sound Barrier: Mineral wool has better sound dampening qualities than fiberglass. This is why is is used in commercial buildings and automobiles.
2. Heat and Smoke Transfer: Because it burns at a higher temperature the rock fibers will not break down during the first minutes of a house fire allowing the occupants to evacuate without being exposed to noxious fumes from the next room.
3. Rodents:Unlike fiberglass rodents do not like mineral wool and will not makes nests in it.
4. Water and Mold: Fiberglass acts like a sponge for water and will hold dampness in its fibers. Mineral wool sheds water and is a deterrent to mold growth. It also holds its shape when wet and will not sag causing gaps in the insulating qualities of the wall.
5. Installation: It is difficult to cut fiberglass finely where mineral wool is easily cut to exact pieces.
6. Cost: Fiberglass batts are ¾ the price of mineral wool.
For more information on insulating contractors please consult our Contractor Directory or simply post your project online.
Kim Kinrade writes for renovation, travel and news sites. When he is not doing this, or renovating old houses, he finds the time to write novels.
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