Kinds of Thermal Insulation

All the materials used to prevent heat losses from a body are known as thermal insulation, and which be categorised into following nine basic kinds : 

1. loose fills, 
2. blankets, 
3. batts, 
4. structural insulation board,
5. slab or block insulation, 
6. reflective insulation, 
7. foamed-in-place, 
8. sprayed-on, and 
9. corrugated. 

Loose Fill Insulation 

This is generally bulky and can be divided into two main types : 

1. fibrous, and 
2. granular. 

The fibrous type is made from mineral wool - rock wool, glass wool or slag wool-or vegetable fiber-usually wood fiber. Granular insulation are made from expanded minerals such as perlite and vermiculite or from ground vegetable matter such as granulated cork. 

Blanket Insulation 

These are made of felted fiber, usually of a mineral nature, manufactured to predetermined thicknesses of 1,1.5,2,3 and 4 inches, respectively. Some blankets are made in 8 ft lengths, others are put up in rolls of from 40-100 linear feet, depending on the thickness. Blankets are used where large areas must be insulated. These include such places as side walls in new construction, overhead places in floored attics, between joists in unfloored attics in crawl spaces and over suspended ceilings. 

Batt Insulation 

Batts are similar to blanket? in many respects except that they are 48" long or less. They may have, with reference to stability, a backing on one side or be completely enveloped; and these are used for the same purposes and in a similar manner as are blankets. 

Structural Insulation Board 

These boards are made primarily from organic fiber - wood, cane, straw or cork. Some boards are impregnated with asphalt during the manufacturing process, while others are given a coat of asphalt after they are made. These boards are used in a variety of ways, including exterior wall sheathing, roof decking, roof insulation under built up roofing, shingle backer, interior finish board, insulating form board.

Rigid Slab Insulation 

This type of thermal insulation is so called because the units are relatively stiff and inelastic. In most cases inorganic materials are used in their manufacture. Insulation falling into this category include mineral wool with binder, foamed plastic, cellular glass, foamed concrete, cellular hard rubber, shredded wood and cement. The insulative value of these materials lies in the fact that the basic material is a non-conductor and that the finished product contains millions of isolated air cells, ideal for insulation. Rigid slab insulations are particularly useful for such applications as roof deck insulation, perimeter insulation, pipe insulation, cold storage work and cavity wall insulation. It can also insulate masonry walls without furring. 

Concrete using as aggregate such light weight materials as vermiculite, perlite or expanded clay is useful as an insulation because of the cellular structure of the aggregates. Poured in place, it becomes a rigid slab that possesses structural strength as well as insulation value. This type of concrete is widely used as the base portion of a concrete slab on grade floor and as an insulating roof deck.

Reflective Insulation 

Reflective insulation is made from such materials as aluminium or copper foil or sheet metal with bright surfaces that reflect heat rather than absorb it. Aluminium foil is produced in sheets or rolls and made up into blankets. Other types of blankets consist of multiple-layer or accordian-style formations of paper covered with foil; special papers coated with a polished aluminium pigmented heat-reflective coating are produced to act as reflective insulation. These are supplied either in single sheets or with two sheets laminated by an asphalt adhesive. This material can be used on one side of a mineral wool blanket. 

Reflective insulation can be used in strut, rafter and joist spaces, to insulate walls, roofs, ceilings and floors; and this insulation is also available for use in,cold storage. It is necessary to install reflective insulation so that the reflective surface faces an air space of at least 3/4".  In ceilings, air spaces of at least 1 1/2" are more effective. 

Foamed-in-Place Insulation 

This is a polyurethane product, made by combining a plyisocryanate and a polyester resin. Trichlorofluoromethane also can be used as a blowing agent in some cases, depending on the foam properties required. 

This type of insulation can be applied either by pouring or by spraying. In either case. the two basic ingredients are drawn from their containers measured and mixed by machine. Wen the pouring system is being used, a carefully measured  amount of the mixture is deposited in an existing cavity. The mixture reacts and foams up to fill a predetermined portion of the space to be filled. This volume of foam is called a 'lift', and normally is limited to a height of about 14". The process is repeated till the space is completely filled. By this system, any desired thickness of insulation can be applied according to specification.

Sprayed-on Insulation 

Several materials are used in this type of application one of them being the polyurethane foam described above. Other commonly used materials are asbestos fibre mixed with inorganic binders vermiculite aggregate with a binder such as portland cement or gypsum, and perlite aggregate using gypsum as a binder. 

This type of insulation also seals the cracks and crevices to prevent dust from shifting through and eliminates joint and lap problems common to cormgated building materials. It also tends to protect metal from corrosive action. 

Corrugated Insulation 

This type of insulation is usually made from paper formed into shapes that allow producing enclosed air pockets. One type is produced by shaping heavy paper into a series of small regular semicircular corrugations and covering both sides with a sheet of flat paper to give strength and produce the air pockets. This is produced either in sheets or rolls. 

A more rigid type of corrugated insulation is made by forming a honey comb shaped mat with paper and covering both sides with a flat paper sheet. The whole thing is given its rigidity by spraying with a thin coating of portland cement slurry or other type of stiffener. The resulting paper mat is quite strong and may be used for non-bearing partitions without further support, plastered on both sides.