Insulation Options in Atlanta

Insulation Options

The most common options for increasing insulation in a home are:

• Fiberglass Insulation – Batt or Blown;
• Open Cell Foam.

Fiberglass Insulation

Fiberglass insulation is the most common type of insulation. Fiberglass insulation works by slowing the transfer of heat. For example, heat that enters the attic in summer is slowed by insulation on the attic floor, reducing the amount of heat that is transferred into the living space below. The ability of insulation to resist heat transfer is measured in R-Value, which stands for “resistance to heat flow”. The higher the R-Value, the better the resistance to heat flow and the greater the insulating value. R-Value is determined primarily by the thickness of the insulation.

Fiberglass insulation is made from 100% melted sand, making it an environmentally friendly product.

Fiberglass insulation

is available in two basic forms: Batt or Blown.

Batt Insulation

Batt Insulation, sometimes referred to as “blanket” insulation, is available in different thicknesses, depending on the desired R-Value (R-30 for crawl spaces or ceilings with 2 x 10 construction, R-19 for ceilings and walls with 2 x 8 construction and R-13 for walls with 2 x 4 construction). Batt Insulation is also available in different widths to fit the spacing between wall studs or floor joists.

Batt Insulation can be used to insulate walls and ceilings, including ceilings and/or walls (i.e., knee walls) of bonus rooms or cubby holes, exterior walls in unfinished basements or renovation projects and ceilings of crawl spaces[3]. Batt Insulation is one of the most economical and practical solutions for these situations. If Batt Insulation is used on the underside of a roof (such as in a cubby hole off a bedroom), baffles must be installed first to maintain proper roof ventilation.

While Batt Insulation can be used to insulate an attic floor, the gaps created when Batt Insulation is cut to fit around pipes and wiring significantly reduce its performance (which is why blown insulation, described below, is a alternative for attic floors).

Batt Insulation is available as Faced or Un-Faced.

Kraft Faced Batt Insulation is the most common form of Batt Insulation. It has a vapor barrier on one side, which should always face toward the living space in order to keep moisture from penetrating the home, thus reducing the opportunity for mold growth. If Kraft Faced Batt Insulation is installed in a:

• Basement ceiling – vapor barrier should face “upwards”, towards the living space above the basement;
• Basement wall (to condition the basement) – vapor barrier would face “inward”, towards the basement;
• Cathedral ceiling – vapor barrier would face “downward”, towards the room.

Un-faced Batt Insulation is used in attic floors, as well as to insulate interior walls in new construction applications.

Batt Insulation is installed in walls by fitting the insulation in the cavity between the studs and stapling it to the face of the studs.

Batt Insulation is installed in crawl spaces and ceilings using wire supports (called Tiger Teeth) between the joists to hold the insulation in place.

While Batt Insulation is available in standard widths designed to fit inside most floor joists and wall studs, it still needs to be cut to fit into floor and wall cavities and around obstacles (such as ducts and/or plumbing), leaving gaps for air leakage and resulting in non-optimal performance. In addition, you have to be careful not to squeeze Batt Insulation into the cavity, because compressing the insulation can reduce its performance.

The Department of Energy estimates that installing Batt Insulation in a wall or ceiling in a sufficient amount to raise R-Value to the level recommended for maximum energy efficiency[4] can reduce total utility bills by up to 10%.

Note: The estimate from the Department of Energy is based on tests of thousands of homes, of varying sizes and in varying conditions. The actual cost savings will depend on a number of factors, including the size of the home, the size of the attic, existing levels of insulation, air leakage in the home, etc.

Fiberglass Blown Insulation

Fiberglass Blown Insulation, or “loose fill”, is made up of small pieces of fiberglass insulation that is blown into a wall or floor cavity using special pneumatic equipment.

Like Batt Insulation, the insulating performance of Blown Insulation is measured in R-Value, which is determined primarily by the depth blown (measured in inches). The deeper the insulation is blown, the higher the R-Value.

In retrofit applications, Blown Insulation is primarily used to insulate an attic floor. With Batt Insulation, gaps between the insulation and the construction materials forming the cavity (such as the gaps caused when Batt Insulation is cut to fit around pipes and wires) can reduce the effective R-Value by as much as 50%. Blown Insulation creates a seamless blanket of insulation, filling irregularly shaped areas and around obstructions, minimizing air leakage. That’s why blown insulation is more efficient for an attic floor application (even though the estimated savings, as described below, are the same).

If not blown in properly, however, the thickness can vary across the floor, resulting in non-uniform R-Values across the attic.

Blown Insulation can be applied over existing insulation for increased energy efficiency. For example, the Department of Energy recommends an R-Value of 49 for proper attic insulation, which translates to 19″ of insulation. The average attic only has about 6″ of insulation, representing an R-Value of R-11. To bring the attic up to recommended levels (R-49), you would need to add about 13″ of insulation (bringing the total to 19″).

The US Department of Energy estimates that blowing fiberglass insulation in an attic to R-49 (19″) can reduce total utility bills by up to 10%.

When installing Blown Insulation in an attic, you have to be careful not to block the soffit vents, which are critical to maintaining proper attic ventilation. Proper attic ventilation, provided through soffit vents, gable vents, ridge vents and attic fans, prevents premature deterioration of roof shingles. Consequently, maintaining proper ventilation is critical to maintaining the roof warranty.

Baffles can be used to keep Blown Insulation from blocking airflow through soffit vents. The baffles are stapled to the bottom side of the roof decking, between the rafters and above the soffit vents, creating an unobstructed pathway for air to enter the attic. Many contractors cut costs by not using baffles. Instead, as they get closer to the soffit vents, they reduce the amount of insulation blown onto the floor. The result is uneven levels of insulation and reduced performance. Even worse, the customer paid for insulation they did not get.

When installing Blown Insulation, it is important to keep the insulation away from recessed lighting, unless the fixtures are rated for insulation contact (i.e., IC-rated). Surrounding a non-rated fixture with fiberglass insulation can cause the fixture to overheat, reducing the life of the light bulb and, more importantly, increasing the risk that surrounding building materials could catch fire. Metal can covers can be used to protect recessed lights from new insulation, reducing risk of fire.

As described above, insulation slows the transfer of heat, but it doesn’t stop air flow. Consequently, air will continue to flow between the attic and the conditioned living space below via leaks. Two common areas for air leakage from an attic are the Attic Door or Hatch and Attic Fans. Pull down doors or hatches are typically made of plywood and are not insulated. In addition, air leaks around the edges. Attic fans are a significant source of air leakage into and out of the attic.

Attic doors or hatches can be insulated with weather stripping, which protects against leaks through the edges of the door, or with custom covers. However, a custom cover provides better protection because it insulates the door or hatch, which is typically made of plywood and is not insulated. Attic fans can also be insulated with custom covers.

Blown Insulation is used in new construction to insulate walls. While it can be used to insulate walls in an existing home, it is a messy proposition. You would have to drill holes in the walls to gain access and then patch the walls afterwards. Consequently, most retrofit applications for Blown Insulation focus on the attic floor.

Blown Insulation can be made from fiberglass or cellulose. Cellulose is typically made from recycled newspapers, which is why it is considered environmentally friendly. However, cellulose insulation has a number of disadvantages relative to fiberglass. Cellulose is very dusty, which can cause problems for homeowners with allergies, is flammable, raising safety issues, and it tends to compact over time, reducing its effectiveness.

By contrast, fiberglass blown Insulation is not dusty, is not flammable and does not compact over time. In addition, it is made from 100% melted sand, so it is arguably just as environmentally friendly.

Fiberglass insulation does not reduce attic temperature; it simply slows the rate at which the heat moves through the attic and into the home. Radiant barrier actually reduces the amount of radiant heat that enters the attic, thereby reducing the heat that transfers through the insulation into the home.

During the summer, solar energy is absorbed by the roof, heating the roof and radiating heat downward, toward the attic floor. In the winter, radiant heat leaves the home through the attic. Radiant barrier, when applied to the underside of the roof, works by reflecting radiant heat away from the attic in summer, and back into the attic in winter, reducing the amount of heat transfer into and out of the home. Radiant Barrier blocks 75% of the radiant heat from entering and leaving the home through the attic. In winter, radiant barrier reflects radiant heat back into the house. In summer, it works like a space suit, reflecting the sun’s heat before it can warm up your attic.

The result is a significant reduction in attic temperatures, which in turn reduces the load on HVAC equipment and ducts, significantly increasing the efficiency of the HVAC system. Tests have shown that installing radiant barrier in the attic will reduce heat gain and loss through the ceiling by up to 40%.

While radiant barrier significantly reduces the radiant heat that enters the attic, some amount of radiant heat still passes through the roof. In addition, hot air still enters and leaves the attic through soffit and gable vents.

Consequently, insulation is still needed on the attic floor to slow the transfer of any remaining heat into the conditioned space below. In addition, air leakage through an attic door or hatch or attic fan should be blocked with covers.

Open Cell Foam

Open Cell Foam is a state-of-the-art insulation system that protects a home equally against both heat and cold. It also acts as an air barrier, eliminating air leakage that can account for significant heat loss or gain in the average home.

Open Cell Foam offers the most significant energy savings of any insulation alternative. Although it is more expensive upfront, it provides significantly greater ongoing energy savings (because, in addition to blocking the transfer of heat, it acts as an air barrier). It is primarily applied to the underside of the roof decking (and offers maximum savings if the HVAC unit is located in the attic) or to the ceiling of a crawl space. In new construction or renovations, Open Cell Foam is also used in wall applications.

Open Cell Foam is applied to the surface as a liquid which then expands to 100 times its volume in seconds to fill every crack and crevice. It delivers a perfect fit for cavities of any shape, providing a continuous, protective barrier that blocks heat transfer and virtually eliminates air leakage.

A 3 ½” application of Open Cell Foam can block 92% of heat transfer AND create an air barrier, producing a thermal envelope for increased energy efficiency. By keeping more conditioned air inside the home (the building envelope), the HVAC system doesn’t have to work as long or as hard to keep the home at a consistent, comfortable temperature. This allows for HVAC equipment to operate at optimal efficiency.

With Open Cell Foam, air flow from outside is virtually blocked, so the attic temperature approaches the temperature of the home’s interior (rather than the outside temperature). Thus, there is no need for additional insulation on the attic floor. By comparison, radiant barrier blocks 75% of radiant heat (versus 92%), and hot air still enters and leaves the attic through existing ventilation. Consequently, radiant barrier will reduce attic temperatures, but only to the level of the outside temperature, so additional insulation is needed on the attic floor to achieve maximum efficiency.

The US Department of Energy estimates that the use of foam in an attic can reduce the heat gain or loss by 50%, which translates into total savings on utility bills of up to 25%.

Other benefits of Open Cell Foam include:

• It seals the attic, so it is not necessary to cover attic pull down doors or fans;
• It is water permeable; it lets water pass through, so roof leaks can be located;
• It is flame retardant (but some brands of foam still require an ignition barrier);
• It is NOT a food source for mold or pests;
• It is a green product, comprised of 99% air (and contains no formaldehyde); and
• It is 100% water-blown and does not contribute to global warming.

Open Cell Foam can void shingle warranties if it is applied directly to the underside of the roof decking (which is exactly how most contractors apply it). This voids the shingle warranty because it eliminates air flow under the decking. In order to maintain proper air flow under the roof decking, it is necessary to install some form of baffle or sheathing to the rafters, leaving at least 2″ of air flow beneath the roof decking, and then apply the foam to the baffle or sheathing[5].

Open Cell Foam can be an effective tool for reducing energy costs and moisture management when applied to the ceiling of a Crawl Space. Crawl spaces are breeding grounds for moisture, which can lead to mold. Mold requires air, water and a food source to develop. Open cell foam blocks air, is not a food source and reduces moisture, reducing the potential for mold growth.

Foam can be applied directly to a wall or ceiling if it does not form the under-decking of a roof because there would be no requirement to maintain proper ventilation. This makes foam even more attractive for ceiling and wall applications in a bonus room or crawl space where roof ventilation is not an issue.

The US Department of Energy estimates that the use of foam in a crawl space can reduce total utility costs up to 12%.

Many open cell foam products used in residential applications require that an ignition barrier be applied to the foam AFTER it has been applied to the ceiling or wall. The ignition barrier is required in order to minimize the risk of fire. A limited number of open cell foam products have been certified such that they do NOT require an ignition barrier (and thus can be applied to the ceiling or wall without the additional cost of applying an ignition barrier). Unfortunately, many contractors are not aware of this requirement, or simply choose to ignore it in order to reduce costs.

Closed Cell Foam is another form of foam insulation that has historically been used in commercial applications. Closed Cell Foam dries very hard, as opposed to Open Cell Foam which remains flexible. The result is that Closed Cell Foam does not expand and contract along with the building materials it is attached to. This causes the foam to delaminate, resulting in leaks.[6] Consequently, Open Cell Foam is a better option for residential retrofit applications.

[3] When installing Batt Insulation in a crawl space, a vapor barrier should be installed on the ground to prevent moisture from rising through the insulation and into the sub-floor or flooring above.

[4] R-30 for 2×10 construction, R-19 for 2×8 construction and R-13 for 2×4 construction.

[5] Open Cell Foam is “water” permeable, but not “vapor” permeable like radiant barrier coating. When applied directly to the underside of the roof, it eliminates ventilation, thus voiding the shingle warranty.

[6] This is not typically an issue in commercial construction because the foam is applied to steel or concrete instead of lumber, thus there is no expansion or contraction of the building materials with changes in temperature.

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