The real value of foam insulation for steel buildings can be recognized during the application process. Since the materials are spray-applied and adhere to the substrate they come in contact with, every crack and crevice is filled along the way, creating a tight building envelop that amounts to reduced energy consumption. SPF insulation materials provide thermal and moisture management systems for steel buildings.

In addition, compared to other insulation materials such as polystyrene and fiberglass, the R-value of spray-applied polyurethane insulation for steel buildings is almost twice as much. Besides, polyurethane insulation can:
· Increase the structural stability of steel buildings
· Serve as vapor barrier that helps reduce build up of moisture
· Provide acoustical insulation

On the downside, there are many concerns about the use of SPFs for insulation of steel buildings. First, extra care must be taken when handling polyurethane foam insulation because this material is combustible. During storage and installation, they must not be exposed to open flames, cutting and welding torches, electric heaters, high intensity lamps, and smoking materials.

In addition, an SPF system, alone, can be costly when compared to traditional insulation products for steel buildings. During the actual application, fumes and mists from the spraying process are created that can be harmful. Contact with these can pose various health effects to the skin, eyes, and respiratory system. Applicators, helpers, and occupants of steel buildings within close proximity to the spray operation, must protect themselves from fumes, mists, and spills through the use of respirators, solvent resistant gloves, and protective clothing.

Still on the subject of spray-applied polyurethane foam insulation for steel buildings, the following steps have already been undertaken including determination of insulation thickness, selection primer, selection of a vapor retarder, and selection of the spray polyurethane system. The last step is to select either a protective coating system and a thermal barrier, the choice of which depends on the place of application of the insulation material.

When the SPF system is applied to the exterior surfaces of steel buildings, it is essential that the foam be covered with a protective elastomeric coating system. This enhances the durability of the foam system by protecting it from the sun’s UV rays and other meteorological phenomena. It is of utmost importance that the elastomeric coating must bond to the polyurethane foam, making the coating a basic part of the insulation system for steel buildings.

Elastomeric coating systems that are designed for use over foam insulation of steel buildings form a protective membrane that provides long lasting water-resistance.

In choosing the appropriate protective coating system, consider the physical and performance characteristics of the material such as:
· Resistance to inorganic bases, acids, alkaline materials, and hydrocarbon solvents
· Permeance to water vapor
· High elongation values
· Preservation of physical properties through the years
· Resistance to UV rays
· Resistance to hail impact
· Life expectancy
· Ease of maintenance
· Resistance to dirt pick-up
· Adhesion to the SPF
· Combustibility
· Attractiveness

On the other hand, if the SPF system is applied to the interior surfaces of steel buildings, it must be protected by a 15-minute thermal or fire barrier. This thermal barrier is designed to slow the temperature increase of the foam in the event of a fire and to delay the foam’s involvement in a fire.

In the choice of a thermal or fire barrier, consider the following:
· Building code requirements
· Adhesion to the SPF
· Existing environment where it is to be used
· Ease of maintenance
· Attractiveness

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Spray-applied polyurethane foam may be applied to interiors as well as exteriors of steel buildings. In exterior applications, the SPF must be covered with an elastomeric coating for weather protection. On the other hand, when applied to interior surfaces of steel buildings, the SPF must be covered with a 15-minute thermal barrier for fire protection.
Some projects may even require the use of vapor retarders for condensation control and an attractive finish.

For a successful application of spray-applied polyurethane foam to surfaces and components of steel buildings, several general practices must be observed:

· Surface preparation
The SPF insulation system may be composed of the primer, vapor retarder, and the actual spray-applied polyurethane foam. Prior to the application of the SPF system, all the building components must be fixed firmly against movement. All the surfaces must be dry, free of loose dirt or any undesirable substance that would hinder the adhesion of any of the system components.

· Selection of primer
If the project requires a primer, selection is based on the type of substrate to be sprayed, the final use of the steel building, and the actual recommendations of the SPF and primer manufacturers.

· Selection of Vapor Retarder
Some building codes require an interior vapor retarder or insulation facing for steel buildings. The need and location of a vapor retarder are based on the following factors:

1. The design and degree of vapor transmission
a) Interior design temperature
b) Interior design humidity
c) Exterior design temperature
d) Exterior design humidity

2. The intended location of the SPF application
a) Interior wall or ceiling surfaces of steel buildings
b) Exterior wall or roof surfaces of steel buildings

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Aside from fiberglass insulation, another type of insulation system for steel buildings is spray-applied polyurethane foam. Polyurethane foam bonds well with the steel surface, even conforming to irregular surface profiles and providing an effective seal, that’s why the insulating material is also used as waterproofing augmentation for steel buildings.

Spray-painted polyurethane foam can be used to insulate steel building interiors and exteriors. However, the performance of the SPF system depends not only on the polyurethane foam but also on the other components and the surrounding conditions inside and outside of steel buildings.

To ensure SPF’s maximum performance, it is crucial that material suppliers be consulted first on the different aspects of the insulation system including material selection, expansion joints, load design, choice of vapor retarders, thermal barriers, and flashing details.

The first crucial step of this project is to determine the thickness of the insulation material. The best method to do this is to make an analysis of the following situations and determine the minimum value for each. The greatest of these values is the best insulation thickness for the particular steel building.

· Building and Energy Codes: Steel buildings are required by most code agencies to meet the energy conservation standards prescribed by the Council of American Building Officials (CABO) Model Energy Code.

· Condensation Control: Condensation can occur inside steel buildings when moisture collects on exposed metal surfaces especially during humid days. Warm air holds more moisture than cold air, that’s why condensation is created from warm air. The temperature at which air is saturated and can no longer hold the moisture is called dew point. To control condensation, the insulation thickness should be based on the design dew point as well as the design exterior ambient temperature of steel buildings.

· Economic Thickness: It is true that greater insulation thickness significantly decreases heat and cooling costs. However, at some point, the cost of adding insulation exceeds the expected energy savings. The economic thickness calculation establishes how much insulation thickness should added that meets a specified return on investment from savings in energy costs.

· Minimum Practical Thickness: To achieve proper foam cure and to conform to the substrate, spray polyurethane foam must be applied to a minimum thickness. For most smooth substrates, the minimum is one inch. On the other hand, unusual substrate configurations in steel buildings may require greater thickness to achieve an appropriate finished foam surface.

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