Thermal insulation in buildings is an important factor to achieving thermal comfort for its occupants. Insulation reduces unwanted heat loss or gain and can decrease the energy demands of heating and cooling systems. It does not necessarily deal with issues of adequate ventilation and may or may not affect the level of sound insulation. In a narrow sense insulation can just refer to the insulation materials employed to slow heat loss, such as: cellulose, fiberglass, rock wool, polystyrene, urethane foam, vermiculite. But it can also involve a range of designs and techniques to address the main modes of heat transfer - conduction, radiation and convection materials., and earth or soil.
The effectiveness of insulation is commonly evaluated by its R-value. However, an R-value does not take into account the quality of construction or local environmental factors for each building. Construction quality issues include inadequate vapour barriers, and problems with draft-proofing. In addition, the construction properties and density of the insulation material itself is critical. For example, according to Leah Twings, Quality Compliance Manager of Textrafine Insulation, fiberglass insulation materials made from short strands of glass layered over each other is not as durable as insulation made from long entangled strands of glass.
The Different Types and Their Advantages and Disadvantages
Fiber glass is a soft wool-like material that is usually pink or yellow. It is used as insulation, in weatherproofing, and as textile material. It was originally used as a "safe" substitute for asbestos. Fiber glass was used as a liner inside air supply ducts and air handler compartments of the ventilation system of homes and buildings built from the early 1960s through the late 1980s. It was used in ventilation systems as an insulator to prevent loss of hot or cold air and to reduce the noise from the blower fan. Fiber glass liners inside ducts were a problem because if it got wet it could become a breeding ground for microorganisms.
There are a few more problems with fiber glass. One is there are some health problems associated with it. For example, it can cause a skin allergy and there is debate on whether or not fiber glass may cause cancer. It may also trigger reactions in those people who are chemically sensitive since most fiber glass insulation is produced using a phenol formaldehyde binder to hold the fibers together. These binder materials may release offending amine or "dear-fish" odors in high humidity situations.
Another thing that should be considered when choosing insulation are the ingredients that go into it. The largest fiber glass insulation manufacturers all use at least 20 percent recycled glass in their insulation products to comply with the US Environmental Protection Agency (EPA) recycled-content guidelines. One of the raw materials that is used to make fiber glass more flexible and fire retardant is boron. However, there are only two large deposits of boron in the world: one in the southwest US and one in Turkey. Since the total known US reserves of boron is just 200 years, other renewable alternatives should be considered.3
While mineral wool was at one time the most common type of insulation, its market share was largely lost to fiber glass in the 1960s and 1970s. In the past few years, however, the product appears to have begun a comeback. There are currently several manufacturers of mineral wool in the US and about eight plants that produce it. "Mineral wool" actually refers to two different materials: slag wool and rock wool. Slag wool is produced primarily from iron ore blast furnace slag, an industrial waste product. Rock wool is produced from natural rocks. Slag wool accounts for roughly 80 percent of the mineral wool industry, compared with 20 percent for rock wool. Given the relative use of these two materials, mineral wool has, on average, 75 percent post-industrial recycled content.
Cellulose is perhaps the best example of recycled material use in insulation. Most cellulose insulation is approximately 80 percent post-consumer recycled newspaper by weight; the rest is comprised of fire retardant chemicals and, in some products, acrylic binders. The biggest long-term performance concern with cellulose insulation is possible loss of fire-retardant chemicals. Because borates are water soluble, they can leach out if the insulation gets wet.
This type of insulation uses cotton and polyester mill scraps with plastic fiber added for three-dimensional loft and borates added for pest and combustion resistance. This insulation costs about 15 percent to 20 percent more than comparable fiber glass insulation.
Bales of straw have been used for exterior wall insulation. Of course, precautions need to be taken to prevent insect infestation and well as moisture intrusion.
There are different types of foam insulation materials. These include:
Styrene, like that used in polystyrene insulation, can cause irritation of the eyes, nose, and respiratory system; headache, fatigue, dizziness, confusion, malaise (vague feeling of discomfort), drowsiness, weakness, unsteady gait; possible liver injury; and reproductive effects. Many foam insulations use recycled plastic resin such as that found in some extruded and expanded polystyrene (EPS). Of the foam insulations, polystyrene is easier to recycle than polyisocyanurate or polyurethane since it can easily be melted down and reformed into other products. The simplest recycling involves crumbling the old EPS into small pieces and re-molding them into usable shapes. Polystyrene used to be blown with chlorofluorocarbons, or CFCs, that destroy the earth's protective ozone layer. Now extruded polystyrene (XPS) uses hydrochloro-fluorocarbons (HCFCs) that are not as dangerous but can still be detrimental to the earth's protective ozone layer.
EPS is the only common rigid foam board stock insulation made with neither CFCs nor HCFCs. During manufacture, polystyrene beads are expanded with pentane, which is a type of flammable gas. An advantage of board stock insulation is that if it can be removed without breaking up, it can often be reused.
Two new types of foam insulations that do not use CFCs or HCFCs are:
Other Considerations Regarding Insulation
Exterior Insulation and Finish Systems (EIFS) are a type of building product that provides exterior walls with an insulated finished surface, and waterproofing in an integrated composite material system.
The word "System" should be singular, therefore the acronym EIFS is not plural. It is inaccurate to says "EIFS are", which appears several times in this article.
Although often called "synthetic stucco", EIFS is not stucco. Traditional stucco is often called Portland Cement Plaster, and is a centuries-old non-insulating material. Stucco consists of sand, Portland Cement, and water, and is a hard, dense, thick, non-insulating material. EIFS is a lightweight synthetic wall cladding that includes foam plastic insulation and thin synthetic coatings. There are also specialty stuccos that use synthetic materials but no insulation, and these are also not EIFS either. A common example is what is called one-coat stucco, which is a thick, synthetic stucco applied in a single layer (traditional stucco is applied in 3 layers). There is also an EIFS-like product called a Direct-Applied Finish System (or DAFS), which is essentially an EIFS but without the insulation, and has quite different characteristics.
EIFS are proprietary systems of a particular EIFS producer and consist of specific components. EIFS are not generic products made from common separate materials. To function properly, EIFS needs to be architecturally designed and installed as a system.
There are a number of versions of EIFS. The most basic and common EIFS is called a barrier EIFS (also known as a traditional or conventional EIFS). Another type is called an EIFS with Drainage, which is a barrier EIFS to which a water drainage capability has been added.
A basic EIFS includes only the insulation and EIFS materials (coatings, adhesives, etc.). Other types o resin such as that found in some extruded and expanded polystyrene (EPS). Of the foam insulations, polystyrene is easier to recycle than polyisocyanurate or polyurethane since it can easily be melted down and reformed into other products. The simplest recycling involves crumbling the old EPS into small pieces and re-molding them into usable shapes. Polystyrene used to be . EIFS insulation comes in individual pieces, usually 2' x 4', in large bags. The pieces are trimmed to fit the wall at the construction sitocarbons (HCFCs) that are not as dangerous but can still be detrimental to the earth's protective ozone layer.
does not include flashing or sealants as part of the EIFS.
EIFS can be used on a wide range of buildings, including homes, apartments, condominiums, high-rise buildings, offices, malls, shopping centers, hotels, motels, clinics, government buildings, and so on. It can also be used to create facades and soffits on shopping centers, and for decorative purposes (to look like stone, or to create signage or artwork). EIFS is not a roofing material.
EIFS can be used on new buildings and also can be installed on existing walls, called "retrofitting", to upgrade the appearance and provide insulation, without affecting the activities indoors during the renovation (EIFS is installed completely from the outside of the building).
EIFS has a number of features that contribute to its popularity, including a modern seamless look (although control joints are required at regular intervals to prevent splitting from thermal expansion/contraction), the ability to mimic other materials, reasonable cost, and high energy efficiency. EIFS looks like traditional stucco or concrete, and is very common through North America.
The use of EIFS is regulated by the building codes. However, since EIFS is a relatively new type of wall cladding, many codes do not refer to EIFS by name. EIFS is generally regulated by Evaluation Reports ("ER's") which are technical reports issued by code agencies for a specific product. The ER's go into great detail about how a specific EIFS product can be used. The primary source of ER's in the USA is the Evaluation Services division of the International Code Council.
Known within the UK as "External Wall Insulation Systems" or EWIS.
EIFS is attached to the outside face of exterior walls with an adhesive (cementicious or acrylic based), it should never be attached by using mechanical fasteners such as nails, screws, etc. unless using on a foam shape sometimes called "popouts" or "trim band". Mechanical fasteners can cause virtually unsealable holes in the system, thus making it impossible to be water proof. The supporting wall surface is continuous (not "open framing") and flat, and can be a solid material, or some type of sheathing that is attached to studs. The surface to which an EIFS is applied is called the substrate. Common substrates include concrete, cinder block, brick, cement board sheathing, Dens Glass Gold, USG Securock, exterior grade gypsum sheathing, glass fiber-faced gypsum sheathing, oriented-strand board (OSB), and plywood.
EIFS is usually installed at the construction site by hand by independent professional plastering contractors; EIFS producers do not install EIFS products. EIFS is not a do-it-yourself product - it is not sold through retail stores.
EIFS can also be made as panels. The panels are made in a factory and have a lightweight welded metal subframe. When completed they are trucked to the building site, raised with a crane, and attached to the building frame.
EIFS consists of a number of layers that are installed in the following order. The most basic EIFS (a barrier EIFS) consists of 3 layers:
If an EIFS with Drainage, or water-managed EIFS is installed, a water resistive barrier (aka a WRB) is first installed over the substrate (generally DensGlas Gold, exterior-grade gypsum sheathing, OSB or plywood). The moisture barrier is applied to the entire wall surface with a mesh tape over joints and a liquid-applied membrane or a protective wrap like Tyvek or felt paper. Then a drainage cavity is created (usually by adding some sort of space between the foam and the WRB). Then the other 3 layers, described above, are added. This type of EIFS is required by many building codes areas on wood frame construction, and is intended to provide a path for incidental water that may get behind the EIFS with a safe route back to the outside. The purpose is to preclude water from damaging the supporting wall.
Adhesives and Finishes are water-based, and thus must be installed at temperatures well above freezing. Two types of Adhesives are used with EIFS: those that contain Portland Cement ("cementitious"), or do not have any Portland Cement ("cementless"). Adhesives that contain Portland Cement harden by the chemical reaction of the cement with water. Adhesives and Finishes that are cementless harden by the evaporation of water - like house paint. Adhesives come in two forms. The most common is in a plastic pail as a paste, to which Portland Cement is added. Adhesives are also available as dry powders in sacks, to which water is added. Finishes come in a plastic pail, ready to use, like paint. EIFS insulation comes in individual pieces, usually 2' x 4', in large bags. The pieces are trimmed to fit the wall at the construction site.