Insulation serves a number of important purposes in steel buildings. Besides providing resistance to heat transfer, it also minimizes the buildup of condensation in a building, and reduces the level of outside noise that can be heard within. If you plan on heating and cooling a building, a little extra expenditure on insulation will yield major savings in long-run energy costs.
Traditional fiberglass blankets insulation is not the most efficient choice in a steel building. For the best insulation in this application choose a combination of fiberglass and reflective insulations (such as eFoil or Solar Guard). Pay attention to the facing of your insulation (the side that faces into the building), and make sure to choose something durable. Products with a layer of scrim (nylon or fiberglass mesh) are the best choice. If they also have a light or reflective color, they will help to maintain brightness inside the building.The power of insulation to prevent heat transfer is measured relatively, in “R-values.” The more effective a layer of insulation is, the higher its R-value rating. The table at right shows the respective R-values for several thicknesses of fiberglass blanket, a common insulation material that many people are familiar with.
Liner panels can be installed over the insulation (check with the manufacturer for details) and traditional walls can also be framed on top of the insulation where necessary.
Make sure you consider insulation with good permeability. Find one with a low perm-rating (less than 0.1) and you will reduce the transfer of condensation.
Today, there are a variety of building insulation material options available, and new technologies, as well as long-forgotten ideas, are coming to public attention as thermal resistance and energy savings become more of a concern in green building design. Below, from the Insulation Fact Sheet (DOE 2002,) are the R-values for some common building insulation materials expressed in R-value per inch of material.
* Fiberglass batts 2.9-3.8
* High-performance fiberglass batts 3.7-4.3
* Cotton batts 3.0-3.7
* Sprayed polyurethane foam 5.6-6.2
* Loose-fill Rockwool 2.7-3.0
Good Metal Building Insulation will have the following benefits/features:
1. High R-value (thermal break)
2. Eliminate condensation
3. Radiant heat barrier
4. Not be affected by humidity
5. Vapor barrier
6. Install easily
7. Not allow nesting for rodents, birds or bugs
8. Recognized by ICCES and Qualified by Energy Star
Steel buildings and metal buildings are uniquely affected by:
2. Radiant Heat
Steel building insulation options are limited to insulations that address at least these three factors.
Fiberglass blanket is not the only type of insulation on the market, nor does it provide the best insulation when used by itself. 80% of heat transferred by radiation (like solar heat) goes through fiberglass. Reflective insulations, such as eFoil, and the fireproof Solar Guard, boast the capacity to prevent all three modes of heat transfer (conduction, convection, and radiation). It also bears mentioning that fiberglass packed too tightly (like 6” crammed into the frame of steel building) has a tendency to under-perform. If a rating of R-19 or greater is required, it is better to install a combination of fiberglass blanket and reflective insulation.
The part of the insulation that faces the inside of the building is known as the facing. Facing material must be carefully selected if it is going to be left exposed. In this case, the facing doubles as the inner wall material, and needs to be a type which is reinforced with a layer of scrim (fiberglass or nylon mesh). This will increase its durability, protecting it from punctures and scratches. Because of its more vulnerable location, the durability of wall facing is more important than that of the roof facing. “Bird proof” varieties are available for agricultural buildings. It is also worth noting that the color of exposed facing will contribute to the light inside of a building. With white or reflective foil facing, fewer sources are required to light up the interior. Blackfacing may be preferred for a darker ambiance.
Liner panels (partial, and full-height) are available from some manufacturers, which protect the insulation and contribute to the inner appearance of their buildings. General contractors can also be hired to add walls. When the insulation is covered and protected, the durability of the facing can be reduced.
Permeability – To minimize the transfer of condensation into a steel building, insulation facing with a low perm-rating must be chosen. With a perm-rating of 1.0, plain vinyl is not considered protection against condensation. Facing with a perm-rating less than one-tenth (0.1) will provide sufficient protection against condensation for most applications.
Workability – Certain types of insulation cannot be shipped or installed in cold weather during winter. It is a good idea to ask the manufacturer about the material’s workability if a project is taking place in a cold climate.
For additional information see our ‘Insulation Options’ article