Frequently Asked Questions
- What is the difference between residential grade insulation and NIA Certified Faced Insulation®?
- How should NIA Certified Faced Insulation® be stored at the job site?
- Why is it preferable not to pour concrete in an unventilated building?
- What facing do you recommend for this proposed project?
- I am building a warehouse that will be unconditioned (no heat or air conditioning). Do I need to put any insulation in the building?
- The insulation got wet during installation. Can it still be used?
- The specification calls for NAIMA 202-96® (Rev. 2000) insulation. What does this mean?
- The specification calls for an insulation level of 19°F•hr•ft2/Btu. What does this mean?
- How does heat flow?
- The specification calls for an insulation level of 3.3m2•k/W. What does this mean?
- What is meant by k-value, C-value, U-Value and R-value?
1. What is the difference between residential grade insulation and NIA Certified Faced Insulation®?
NIA Certified faced metal building insulation is designed to provide the specified R-Value and recovered thickness after being laminated to the vapor retarder facing with water based adhesives. Residential grade insulations are not designed to be laminated and therefore not strong enough to withstand the laminating process and then recover to designed thickness and provide the labeled R-Value.
In addition, residential insulation is not manufactured to the widths and lengths needed to fit metal building construction.
2. The specification calls for NAIMA 202-96® (Rev. 2000) insulation. What does this mean?
This standard product specification for manufacturers, designers, and users of metal building insulation systems, promulgated by the North American Insulation Manufacturers Association (NAIMA), covers the classification, composition, and physical properties of flexible fiber glass insulation designed to be laminated with facings providing appropriate water vapor permeance, appearance, and durability properties, intended specifically for use in the walls and roofs of pre-engineered metal buildings. NAIMA 202-96® (Rev 2000) insulation has the strength needed to withstand the compressive forces of lamination and the resilience to recover sufficient thickness so it can deliver full thermal performance. NAIMA 202-96 insulation is used to produce NIA certified faced insulation (see question 1 above).
3. How Should NIA Certified Faced Insulation® be stored at the job site?
Individual rolls of insulation should be packaged in ventilated bags. Rolls should be stored on pallets or other suitable surface in such a way that they are not in direct contact with the ground or slab. Freshly poured concrete gives off a significant quantity of moisture that is corrosive to facings containing aluminum foil or metallized film. Rolls should be covered and protected from weather.
4. Why is it preferable not to pour concrete in an unventilated building?
Freshly poured concrete contains a tremendous amount of moisture that is extremely corrosives to facings with aluminum foil or metalized films. A 10′ x 10′ x 4′ area of concrete contains approximately 24 gallons of water. As the concrete cures, much of this water is liberated into the air, increasing the relative humidity and vapor pressure within the building. This significantly increases the potential for condensation and moisture related problems.
Ventilation is the simplest way to reduce humidity, vapor pressure, and the probability of condensation. Failure to adequately ventilate a building during and after a concrete pour can result in condensation on the surface of the vapor retarder and potentially within the insulation. This is particularly critical in colder temperatures.
5. How can I tell which is the best vapor retarder/facing to use on a project?
There are many factors that should be considered when selecting a suitable vapor retarder.
The selection should be based upon the designed ambient conditions and the intended use of the facility. Factors that should be considered are:
- Permeance—In cold climates, facing with a 0.02 Perm rating are preferred.
- Strength and Toughness—In high abuse application where the facing is likely to be contacted, products with higher tensile and mullen burst strengths should be used.
- Emissivity—In application where low emittance/radiant barrier properties are desired, products with exposed aluminum foil should be specified.
6. I am building a warehouse that will be unconditioned (no heat or air conditioning). Do I need to put any insulation in the building?
All local energy and building codes must be followed to ensure that the building is compliant. In projects where the energy codes do not require the building envelope be insulated, it is suggested that at least one layer of condensation blanket be used in the roof. This will help to prevent severe condensation problem and dripping inside the building.
Realistically, it is far less costly to insulate the roof during construction (regardless of the level of insulation) than it is to try and retrofit a building later. As such, even in unconditioned buildings, it is wise to insulate the building to meet the conditioned space requirements during construction. This will provide ultimate flexibility in the future should the use of the building change.
7. The insulation got wet during installation. Can it still be used?
Studies have shown that thermal performance of wet insulation will be restored once dry, provided the original insulation thickness is maintained.
However, the concern with wet insulation is the possibility that contaminants may have been carried into the insulation by the water and that the dirt and contaminants can become a nutrient source for mold or mildew growth. For this reason, insulation manufacturers recommend that wet insulation not be installed, or be removed and replaced with new, clean, dry insulation.
The severity of the situation and the decision to either allow the insulation to dry in place or be removed is one that will need to be made by the building owner and insulation contractor.
8. The specification calls for an insulation level of 19°F•hr•ft2/Btu. What does this mean?
The specification is typically calling for R-19 fiber glass insulation. The I-P units for the R-value in this case are (°F•hr•ft2)/Btu.
9. The specification calls for an insulation level of 3.35m2•k/W. What does this mean?
The specification refers to metric (SI) R values. The conversion equation for this RSI value to R-Value (I-P) = 5.6783 x 3.35 or R–19 (I-P).
10. How does heat flow?
Heat flow is the transfer of energy from one area to another when there is a difference in temperature between the 2 areas. Heat flows from the higher temperature area to the lower temperature area by one or more of the three following ways: conduction, convection, and radiation.
11. What is meant by k-value, C-value, U-Value and R-value?
All four factors are the measure of an insulation system’s thermal performance. Each factor denotes a different thermal performance characteristic. Here are the definitions:
K-value denotes a material’s effective thermal conductivity, which is a measure of the time rate of steady heat flow through a unit area of a homogenous material induced by a unit temperature gradient perpendicular to that unit area. In simpler terms; how well a material will conduct heat. The lower the k-value of a material, the better its performance as an insulator.
In U.S. units, k = Btu•in/hr•ft2•°F
In SI units, λ= W/m•°K
For most materials, thermal conductivity varies with temperature. Normally, the lower the mean temperature, the lower the k-value – and the better the insulation performance. For building insulation materials, k-values are customarily reported at a mean temperature of 75°F, a compromise between winter and summer conditions. For industrial insulations, k-values are customarily reported over a range of mean temperatures.
C-value denotes a material’s thermal conductance, which is a measure of the time rate of steady heat flow through a unit area of a material or construction induced by a unit temperature difference between the 2 surfaces of the material of specified thickness.
In U.S. units, C = Btu/hr•ft2•°F
In SI units, C = W/m2•°K
The C-value of a material is equal to the k-value divided by the thickness of the insulation. The lower the C-value of a material, the better its performance as an insulator. For example: if the C-value of one inch of fiber glass insulation is 0.24 Btu/hr•ft2•°F, the C-value of 2 inches of the same material will be 0.12.
U-value denotes a construction’s thermal transmittance, or its overall heat transfer coefficient. This is similar to the C-value but is generally used in denoting the thermal conductance of a construction comprised of different materials, such as in a typical building envelope. It also includes the air film resistances on both sides of the construction.
In U.S. units, U = Btu/hr•ft2•°F
In SI units, U = W/m2•°K
The lower the U-value of the construction, the better its thermal insulation performance.
R-value denotes a material’s thermal resistance, or how well it is able to retard heat flow. The higher the R-value, the better its performance as an insulator.
In U.S. units, R = hr•ft2•°F/Btu
In SI units, RSI = m2•°K/W
R-value is useful in determining the total thermal transmittance of a construction such as a building envelope. The R-values of all of the materials comprising the construction, plus the inside and outside air film resistances, are added: the reciprocal of this sum is the construction’s U-value (R = 1/C).