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4. Cold-space floors, such as unheated garages and vented crawl spaces. Also, insulate (4A) any floor area in a room that projects beyond the external wall below; (4B) slab floors constructed directly on the ground; and (4C) foundation walls of unvented crawl spaces as an alternative to floor insulation. To decrease air flows, (4D) extend insulation into the joist space.

5. Joists in a band.

6. Install replacement or storm windows and caulk and seal all windows and entrances.
Consider moisture and air leakage control in each section of your home in addition to insulation. If radon is a problem in your area, you'll need to consider radon and radon-resistant construction techniques as you look into foundation insulation choices. Furthermore, if you reside in a termite-infested area, you must consider how termite protection will affect the type and placement of insulation in your home.

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Attic Insulation

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Typically, loose-fill or batt insulation is installed in attics. When done correctly, loose-fill insulation typically costs less to install than batt insulation and offers better coverage. Learn more about the various forms of insulation. 

Measure the thickness of the attic insulation to determine if it is sufficient. If it is less than the equivalent of R-30, it may be beneficial to add more. Before installing insulation, seal any air leakage and make any necessary roof repairs. Remember to insulate and air-seal your attic access if it is in a conditioned area of the home. 

Knee walls, which are vertical walls with attic space directly behind them, should also be insulated and air sealed. In addition, if you are constructing a new home or remodelling an existing one, ensure that any attic decking that provides additional storage space or a platform for a heating and/or cooling unit or hot water tank is elevated above the ceiling joists to allow for adequate insulation. Insulating the timbers will enclose the system if the air distribution system is in the attic rather than the conditioned space. Consider installing a radiant barrier in your attic if you live in a hot or warm climate to reduce summer heat absorption.

 

Duct Insulation

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Seal and insulate your home's ducts if they are in unconditioned space. Place ducts in the conditioned space when building a new home to prevent the energy losses that come with conventional duct systems.

 

Insulation of the Cathedral Ceiling 

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When cathedral ceilings are adequately insulated, ceiling temperatures will remain closer to room temperatures, resulting in an even temperature distribution throughout the home. Cathedral ceilings must provide ample insulation and ventilation by separating the roof deck from the home's ceiling. This can be accomplished by using truss joists, scissor truss framework, or rafters of sufficient size. Cathedral ceilings constructed with 2x12 rafters, for instance, have the capacity for standard 10-inch batts (R-30) and ventilation. Cathedral ceilings with no ventilation (heated roof design) are also an option. As the need for a vent space is eliminated by the heated roof design, more insulation can be installed within the roof cavity. To prevent moisture intrusion and roof deterioration, the roof cavity must be wholly air-sealed from the conditioned space below.

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Due to its permeability rating, foil-faced batt insulation is frequently used in cathedral ceilings. This rating is frequently required for ceilings without attics. A baffle should be installed between the insulation and roof decking to preserve the ventilation channel.

Consider utilizing high-density R-30 batts, which are as substantial as R-25 batts but can be installed in 2x10 framing. Under the rafters, you can also install rigid foam insulation, which increases the R-value and eliminates thermal bridging through the wood rafters. When used inside a building, rigid foam insulation must be covered with a fire-resistant material. Typically, half-inch plasterboard is adequate, but verify with local building officials before installation.

 

Exterior Wall Insulation

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If your attic has adequate insulation and good air sealing, but your home still seems drafty and cold in the winter or overly warm in the summer, you may need to add insulation to the outer walls. This is more expensive and typically necessitates the services of a contractor, but it may be worthwhile, especially if you live in an extremely cold climate. Consider adding insulation to your home if you replace the exterior siding.

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Consider using blow-in insulation in an existing home, which will provide effective air sealing using the dense pack technique. It may be added to exterior walls without causing too much disruption to your home's completed areas. Consider two-part spray foam or wet spray cellulose insulation if remodelling with open wall cavities. If your wall cavities are not open, try injectable spray foam insulation. If you want to conduct the work yourself, blanket (batt and roll) insulation is a cost-effective alternative to thick pack and two-part spray foam insulation.

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In a new home, first review our material on insulating a new home, which will help you choose from the various types of insulation available. Consider structural insulated panels, insulating concrete forms, and insulated concrete blocks during the design process of your new home. The term "responsibility" refers to determining whether or not a person is responsible for the actions of another person.

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Consider adopting advanced wall framing techniques if you're building a typical framed house. These methods increase the whole-wall R-value by eliminating thermal bridging and increasing the insulated wall area.

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Consider employing insulating wall sheathing instead of wood sheathing products, which provide a higher R-value. Foam insulation:
•    Provides a continuous layer of insulation that decreases thermal bridging through wood studs, thereby conserving energy and         

      enhancing comfort.
•    Less challenging to trim and install than heavier products.
•    Warming the interior of the wall prevents condensation from forming on the interior wall.
•    Typically, more affordable than plywood or oriented strand board (OSB).

If you replace foam sheathing for plywood or OSB, your walls will require bracing or other structural reinforcement.

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Insulating Garage Floors Without Heat

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When insulating floors above unconditioned garages, first seal all possible sources of air leakage. This strategy has the added benefit of minimizing the danger of contaminants (from car exhaust, paint, solvents, gardening supplies, etc.) in the garage migrating into the conditioned space. Also install an air barrier to prevent cold air in the garage from "short circuiting" the insulation underneath the subfloor.

 

Insulating the Foundation

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A properly insulated foundation will keep below-grade rooms comfortable, avoid moisture problems, insect infestation, and radon infiltration, and lower heating expenses. Consider using insulating concrete forms and insulating concrete blocks in new construction to provide both base structure and insulation.

Many builders insulate the outside foundation walls before backfilling them during construction. This method is feasible, although it is inconvenient for existing homes. Because the best foundation insulation materials and installation differ depending on the climate, consult a local insulation professional.

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 If you’re planning a new home.

 

Basement Insulation

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An adequately insulated basement can save money on heating costs and provide a dry, comfortable living space. A basement with exterior wall insulation should be deemed a conditioned space in most instances. Even in a home with an unconditioned basement, the basement is more connected to other living areas than the exterior, so wall insulation is preferable to ceiling insulation.

Adding insulation to the exterior of the cellar walls in new construction will accomplish the following:

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• Reduce thermal bridges and heat loss through the foundation.

• During backfilling, safeguard the waterproof coating from harm.

• Provide some protection against moisture intrusion.

• Make the foundation a part of the thermal bulk of the conditioned space, thereby reducing temperature fluctuations within the space.

• Reduce the possibility of basement surface condensation.

• Save space by implementing insulation on the interior of the room    Reduce thermal bridges and heat loss through the foundation.

 

Adding insulation to the exterior basement walls of an existing residence is impractical. Basement wall insulation offers the following benefits:

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• It is significantly less expensive to install than exterior building insulation.

• Practically any type of insulation can be used.

• It eradicates the possibility of an insect infestation

 

Consider the following factors when installing interior basement wall insulation:

•    Many varieties of insulation require a fire-resistant covering because, when ignited, they release toxic gases.
•    A few inches of interior insulation reduce usable interior volume.
•    It does not protect the damp-proof coating as effectively as exterior insulation.
•    If perimeter drainage is inadequate, the insulation may become drenched due to seepage through the foundation walls.
•   For adequate performance, superior air-sealing details and vapor diffusion retarders are essential.

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Use these R-value recommendations to determine what R-values are appropriate for basement walls in your region. Then select an insulation type: 

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• Blanket (batt and roll) insulation

• Insulating concrete blocks (new construction)

• Foam board insulation

• Insulating concrete forms (new construction)

• Loose-fill insulation

• Sprayed foam insulation (good choice for finished basements).

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​Basements are notorious for having water intrusion, humidity, and mold issues, so moisture control is essential.

 

Crawlspace Insulation

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How you insulate a crawlspace depends on whether it's ventilated or unventilated. Most building codes require vents to aid in removing moisture from the crawlspace. However, many building professionals now recognize that building an unventilated crawlspace (or closing vents after the crawlspace dries out following construction) is the best option in homes using proper moisture control and exterior drainage techniques.

If you have or will have an unventilated crawlspace, the best approach is to seal and insulate the foundation walls rather than the floor between the crawlspace and the house. This strategy has the advantage of keeping piping and ductwork within the conditioned volume of the house so these building components don't require insulation for energy efficiency or protection against freezing. The downside of this strategy is that rodents, pests, or water can damage the insulation and the crawlspace must be built airtight and the air barrier maintained. It’s best to locate the access door to the crawlspace inside the home through the subfloor unless you build and maintain an airtight, insulated access door in the perimeter wall.

 

Slab-on-Grade Insulation

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Cold concrete slabs can be a source of discomfort in a home. An insulated slab is easier to heat, and placing the mass of the slab within your home’s thermal envelope helps moderate indoor temperatures.

Insulating a slab in an existing home can be expensive and disruptive, but if the slab in your home is cold it is possible to dig around the perimeter of the house and install insulation, usually foam board. In most parts of the United States, insulating the exterior edge of a slab can reduce heating bills by 10% to 20%.

Installing slab insulation during the construction process is more straightforward. Slab insulation, typically foam board, is installed either directly against the exterior of the slab and footing before backfilling or under the slab and along the inside of the stem wall of the foundation. Construction details vary widely, so it’s best to consult a building professional in your area. Building America’s climate-specific publications also have useful construction details for different climate zones.

Termites can tunnel undetected through exterior slab insulation to gain access to the wood framing in a home's walls. As a result, some insurance companies won't guarantee homes with slab insulation against termites. Building codes in several southern U.S. states prohibit installing foam insulation in contact with the ground. Slab foundations with interior insulation provide more termite resistance, but some builders in the southeastern United States have even reported termite infestations through foam insulation on contained slabs.

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