A building's wall system must constantly fight the invasion of rain, air, vapor and thermal attacks.The wall's ability to provide a barrier to each of these elements relies upon the use of appropriate materials, installed in the correct sequence. There is no such thing as a perfect wall system; however, a wall system that performs with greater efficiency using new efficient materials is achievable.
07 20 00 Thermal Protection
In this second addition of “ROI-Driven Products," we take a look at insulation, which is a big part of a building’s envelope. When insulation is installed correctly, it provides the necessary R-value to meet the thermal demands of the region and the comfort demands of the building’s occupants. With energy prices on the rise, building envelopes have come under more and more scrutiny. Homeowners and business owners alike are now seeing the need to improve the building envelope and increase its overall efficiency.
Insulation can save you money. Homeowners heat and cool their houses with various types of energy which fluctuate in price on a regular basis due to a variety of variables that are outside of their control. Lowering your thermostat, installing a programmable thermostat, or enrolling in a monthly budget plan could lower your bills; however, you may have overlooked the one thing that can truly lower your energy expenses, insulation. Investing in insulation can save you money, paying you back over time through reduced monthly energy expenses, as well as providing greater year-round comfort and a quieter indoor environment.
According to the U.S. Department of Energy, random air infiltration through gaps and cracks is a leading cause of energy loss in homes, accounting for 25–40% of energy loss in most residential structures. Fortunately, Dow Building Solutions (DBS) has been a leader in building envelope solutions, including air sealing and insulation, for over 60 years. Dow offers the broadest array of solutions for minimizing energy loss and moisture damage caused by air leaks, including FROTH-PAK™ Foam Insulation and Foam Sealant Kits, and GREAT STUFF PRO™ Insulating Foam Sealants and Adhesives. At the International Builders’ Show (IBS) 2011, the DBS booth featured a fun, fascinating, and interactive presentation about GREAT STUFF, which showed how the products work to fill gaps and cracks and how they can help to seal a home, increase energy efficiency, and save money.
Air leaks, or what are commonly known as drafts, occur at penetrable locations along a ceiling, beneath an attic. Common locations where air has the ability to leak into an attic include gaps between sheets of drywall; holes through which wiring runs; and around an attic hatch cover, a chimney, recessed lighting, or plumbing and mechanical vents. During the colder months, as heat rises through your home, these gaps will allow warm, humid air to circulate into the unconditioned attic. Locating and sealing these leaks will prevent a rise in the ambient temperature of your attic. Energy Star has developed a helpful guide, “A Do-it-Yourself Guide to Sealing and Insulating with Energy Star,” that provides information about what materials, precautions, and methods are necessary to seal attic air leaks.
Urea-Formaldehyde (UF) foam was used in homes during the 1970s and early 1980s. However, after many health-related court cases due to improper installation practices, UF foam is no longer available for residential use and has been discredited for its formaldehyde emissions and shrinkage. It is now used primarily for masonry walls in commercial/industrial buildings.
Radiant barriers are installed in homes — most commonly in attics — to reduce summer heat gain and winter heat loss, which helps lower heating and cooling costs. The barriers consist of a highly reflective material that reflects radiant heat rather than absorbing it. They don't, however, reduce heat conduction like thermal insulation materials.
Reflective insulation systems are fabricated from aluminum foils with a variety of backings, such as kraft paper, plastic film, polyethylene bubbles, or cardboard. The resistance to heat flow depends on the heat flow direction. Reflective insulation is most effective at reducing downward heat flow.
Cellulose — a material used as loose-fill insulation — is made from recycled wood fiber, primarily newsprint. The wood fiber is shredded and pulverized into small, fibrous particles that pack tightly into closed building cavities, inhibiting airflow. This provides a thermal resistance of R-3.6 to R-3.8 per inch.
Loose-fill insulation consists of small particles of fiber, foam, or other materials. These small particles form an insulation material that can conform to any space without disturbing any structures or finishes. This ability to conform makes loose-fill insulation well suited for retrofits and for places where it's difficult to install some other types of insulation.
Foam boards—rigid panels of insulation—can be used to insulate almost any part of your home, from the roof down to the foundation. They provide good thermal resistance and often add structural strength to your home. Foam board insulation sheathing reduces heat conduction through structural elements, like wood and steel studs.
Vermiculite and perlite insulation materials are commonly found as attic insulation in homes built before 1950. Vermiculite insulation materials aren't widely used anymore because they sometimes contain asbestos. However, according to the U.S. Environmental Protection Agency, asbestos is not intrinsic to vermiculite. Only a few sources of vermiculite have been found to contain more than tiny trace amounts. Still, if you have vermiculite insulation in your attic, do not disturb it. If you want to add insulation to your attic, use an insulation contractor who is trained and certified in handling asbestos.
Polyurethane is a closed-cell foam insulation material that contains a low-conductivity gas (usually hydrochlorofluorocarbons or HCFC) in its cells. The high thermal resistance of the gas gives polyurethane insulation materials an R-value typically around R-7 to R-8 per inch.
Polyisocyanurate or polyiso is a thermosetting type of plastic, closed-cell foam that contains a low-conductivity gas (usually hydrochlorofluorocarbons or HCFC) in its cells. The high thermal resistance of the gas gives polyisocyanurate insulation materials an R-value typically from R-5.6 to R-8 per inch.
Insulated concrete blocks can accommodate many walls in a home. Their cores are filled with insulation (except for those cells requiring structural steel reinforcing and concrete infill), which raises the average wall R-value. The better concrete masonry units reduce the area of connecting webs as much as possible.
Facings are fastened to insulation materials during the manufacturing process. A facing protects an insulation's surface, holds the insulation together, and facilitates fastening. Some types of facing can also act as an air barrier, radiant barrier, and/or vapor barrier. Some even provide flame resistance.
Blanket insulation — the most common and widely available type of insulation — comes in the form of batts or rolls. It consists of flexible fibers, most commonly fiberglass. You also can find batts and rolls made from mineral (rock and slag) wool, plastic fibers, and natural fibers, such as cotton and sheep's wool.
Properly insulating your slab-on-grade floors not only will help you save on energy bills, but also will improve your home's comfort. Cold concrete slabs can be a source of discomfort in a home. An insulated slab reduces heat loss, making it easier to heat. This reduction in heat loss helps moderate indoor temperatures.
A properly insulated foundation can result in lower heating costs and more comfortable below-grade rooms, if you have any. It can also help prevent moisture problems, insect infestation, and radon infiltration in your home.
Properly insulated exterior walls in your house will not only increase comfort but also help you save on heating and cooling costs. For energy savings, you can add insulation to your walls in an existing house. If you're building a new house, you have many energy-efficient wall insulation options to consider.
Properly insulating your cathedral ceilings will help reduce heat loss in the winter and heat gain in the summer. Insulated ceilings allow ceiling temperatures to remain closer to room temperatures, providing an even temperature distribution throughout the house.
Knee walls — often found in houses with finished attics — are vertical walls with attic space directly behind them. These walls are notoriously leaky and often uninsulated. For energy efficiency, a knee wall and the attic floor in the attic space behind it should be properly insulated and air sealed.
When insulating your home, you can choose from many types of insulation. To choose the best type of insulation, you should first determine the following:
Your state and local building codes probably include minimum insulation requirements, but to build an energy-efficient home, you may need or want to exceed them. For maximum energy efficiency, you should also consider the interaction between the insulation and other building components. This is called the whole-house systems design approach.
Air barriers block random air movement through building cavities. As a result, they help prevent air leakage in your home, which can account for 30% or more of a home's heating and cooling costs. Air barriers also help control moisture in a home. While they stop most air movement, air barriers also allow any water vapor that does enter to diffuse back out again.
Air leakage, or infiltration, occurs when outside air enters a house uncontrollably through cracks and openings. Properly air sealing such cracks and openings in your home can significantly reduce heating and cooling costs, improve building durability, and create a healthier indoor environment.
Board insulation, also referred to as foam-plastic board insulation, can be used in many areas of building construction to provide thermal resistance. It is appropriate for use under concrete floor slabs, at foundation walls, in wall cavities, as a backer material for remodeling with new siding, and in a wide range of roofing applications. Foam plastic boards encompass three types: polystyrene, polyisocyanurate, and polyurethane. All types of foam-plastic board insulation panels need to be protected from the damaging ultraviolet effects of the sun. Additionally, foam-plastic insulation should be protected from fire as it will emit dense smoke containing toxic gases. Unfaced foam-plastic insulation boards used in construction are required by codes to be completely concealed in fire resistant materials. Glass fiber resin mixtures and mineral wool are also manufactured in board products for use in construction applications. Blanket, foamed-in-place, loose-fill, blow-in and sprayed type insulations are summarized in other sections.
This topic includes information related to blanket insulation installed during construction. Blanket insulation is commonly installed along crawl space foundation walls, between studs, joists and rafters. Blanket insulation materials include; fiberglass, mineral wool, plastic fibers and natural fibers.
The purpose of roof and deck insulation is to provide resistance to thermal energy. When insulation can inhibit the flow of thermal energy, the result will be a greater capacity to conserve heating and cooling energy. Heat flows from hot to cold due to conduction, convection and radiation. Heat is measured using the British Thermal Unit (BTU) where a BTU is the energy required to raise the temperature of one pound of water by one degree Fahrenheit. Therefore, a material with a higher R-value will provide greater thermal resistance. The roof of a building can be the structure's largest surface area, and consequently the area in which heat has the greatest opportunity to escape. With the correct type of insulation specified as part of the roof system, it will meet energy performance requirements and codes and provide many years of fundamental performance.
This topic includes information related to thermal insulation installed during construction. Thermal insulation materials are installed in ceiling, attics, crawl spaces, exterior walls, under concrete slabs and around foundation walls, to reduce the rate of heat transfer. Thermal insulation materials are manufactured products that take the form of board, blanket, foam, loose-fill, blown or sprayed materials.
This topic includes information related to blown insulation installed during construction. Blown insulation is commonly installed in between studs, joists and rafters. Blown insulation materials include; cellulose, fiberglass and mineral wool.
This topic includes information related to exterior insulation and finish systems (EIFS) installed during construction. EIFS, commonly referred to as synthetic stucco, is an exterior cladding. They are manufactured, proprietary systems that incorporate polymer based, polymer modified coatings and foam insulation. Additional accessories and material options are available, depending on the manufacturer.