Steel buildings are the most durable structures you can buy, but they are not great when it comes to temperature regulation. In short, metal buildings get seriously hot in the summer and extremely cold in the winter. Also, they are not always great about keeping the moisture out.
Along with your pre-engineered metal building system, you need to purchase the proper insulation. How do you decide which type you need? In fact, how do you measure the efficiency of the insulation you find?
Let’s take a look at what insulation is, how it works, and what it must do to keep your steel building comfortable and moisture free.
How Insulation Works
An understanding of heat flow is necessary to understand how insulation works. The three mechanisms by which heat flows are conduction, convection, and radiation.
- Conduction occurs when heat moves through material. A metal spoon in hot coffee conducts heat into the handle.
- Convection occurs when heat circulates through liquids and gasses. It causes warmer, lighter air to rise, and cooler, denser air to sink.
- Radiant heat moves in a straight line and heats any solid in the pathway that absorbs energy.
Insulation works mainly by slowing conductive heat flow and somewhat by slowing convective heat flow. The material in the insulation blocks heat from moving through it and either into or out of your building.
To mitigate radiant heat, a radiant barrier or reflective insulation is required. A radiant barrier simply reflects the heat away from itself like a mirror.
Types of Insulation
There are several types of insulation. Where is it placed and what it needs to do determines the type you use in each space.
Loose Fill Insulation
Loose fill is exactly as it sounds — it consists of loose fibers or fiber pellets that are blown into structural cavities. It fills corners better than other types and reduces air leakage. Loose fill is also a fair sound barrier compared to other insulation.
Batt and Blanket Insulation
Batt insulation is one of the most inexpensive types of insulation for walls but it can be tricky to install properly. Both batt and blanket insulation are made from mineral fibers made of rock wool or processed fiberglass.
Batt is generally used to insulate floors, walls, and ceilings, and works best for stud spacing at 16 to 24 inches or a standard joist. Some forms have reflective backing to act as a radiant barrier.
Blanket insulation comes in rolls cut to specification. Batt comes in lengths of four to eight feet. Both have a typical R-value of R-3 per inch.
Rigid Board Insulation
Polyurethane, fiberglass, or polystyrene boards cut to the desired thickness make up rigid board insulation. It can have R-values from R-4 to R-8 per inch depending on the type foam or fiberglass used.
Rigid board insulation works best for reproofing flat roofs and on basement walls. It is also installed in cathedral ceilings for perimeter insulation and concrete slab edges. It must be covered with 1/2 inch gypsum board or other flame-retardant material for interior installation, and weatherproof facing is required for exterior installation.
Spray Foam Insulation
Spray foam insulation originates as a liquid with a foaming agent along with polyurethane or other polymer. It is sprayed onto walls, floors and ceilings. As soon as it is applied, the foam insulation expands and become a solid cellular plastic barrier full of air-filled sacs.
It is excellent for filling every space and crevice, and is especially useful for small spaces. It also forms around obstructions to guarantee an airtight fit and eliminating the need for caulking.
Structural Insulated Panels (SIP)
SIPs are made of foam board or a liquid foam insulation core. It is commonly used in unfinished walls, ceilings, floors, and roofs for new construction. SIPs are installed during construction by fitting them them together to form the walls and roof, streamlining construction.
Foam Insulated Metal Panels
Foam Insulated Metal Panels (IMPs) consist of two single-skin metal facings and a factory-foamed-in-place core. IMPs are available for both roof and wall applications. The foam insulation is made of non-chlorofluorocarbon (non-CFC) polyurethane foam. IMPs are sealed to each other at the side laps and to the substructure at all perimeter boundaries, which make them the ideal choice when a continuous air barrier is required.
The R-value of insulation indicates the material’s resistance to heat flow or thermal resistance. The higher the R-value, the better the insulating power.
R-value depends on the material used to make the insulation as well as its thickness and density. However, thickness is not always linear depending on the insulation. For example, as loose fill increases in thickness, the more it compresses from its own weight. Therefore, doubling the thickness may not double the R-value.
The R-value of some types of insulation also depends on the temperature, moisture accumulation, and aging of the material. If you are installing layers of insulation, you can calculate the final R-value by adding the R-values of the separate layers of insulation.
The overall R-value of a wall is determined by the R-value of the wall material, the insulation, and how heat flows through studs, joists, and other materials (an action called thermal bridging), so the R-value of a wall or roof may not match the R-value of the insulation installed.
The Department of Energy has zoned the U.S., including Hawaii, Guam, Puerto Rico, and the Virgin Islands according to temperature, and developed a chart and instructions indicating the recommended R-value of insulation to add to attics, floors, and existing insulation.
The Benefits of Insulation
Insulation conveys multiple benefits for metal buildings.
- Energy conservation — resistance to heat loss or gain and reduced heat transfer result in reduced energy usage, lower utility costs, and reduced emissions from burning fuel.
- Process control — controls temperature fluctuations and allows equipment to run more efficiently.
- Condensation control — moisture is mitigated and reduces the chance for mold growth.
- Freeze protection — mechanical equipment is protected from freezing.
- Fire safety — fire retardant insulation design prevents flame spread and protects people and equipment from fire.
- Noise control — reduces mechanical noise from equipment.
- Personnel protection — keeps occupants comfortable and eliminates unsafe temperature levels.
Insulation isn’t just for cold environments, it also helps your air conditioner to run more efficiently and use less energy in the heat.
If you choose to build with steel, you are getting a durable, versatile, low-maintenance structure that will last for decades. Protect the steel and anything inside the building by installing the right amount and type of insulation to maximize temperature control and minimize heat flow.