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Right - the vapor barrier is extended up the sides of the piers in this crawlspace, which is sealed and insulated to house the HVAC ducts.

Right - the vapor barrier is extended up the sides of the piers in this crawlspace, which is sealed and insulated to house the HVAC ducts.

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When wrapping metal ducts with insulation allow two inches of overlap and staple along the seam with outward clinching staples

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The main trunk line of the ducts runs within an insulated duct chase installed in a notch designed into the roof trusses that runs the length of the home to provide supply air directly to most of the home’s ceiling registers.

The main trunk line of the ducts runs within an insulated duct chase installed in a notch designed into the roof trusses that runs the length of the home to provide supply air directly to most of the home’s ceiling registers.

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Insulation for rigid ducts comes in large rolls like this 4-ft x 50-ft roll consisting of a Foil-Scrim-Kraft (FSK) vapor barrier attached to the fiberglass insulation.

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Right - Spray foam insulation has been sprayed onto the underside of the sloped roof and the gable end wall to provide a sealed, insulated attic for housing the HVAC ducts

Right - Spray foam insulation has been sprayed onto the underside of the sloped roof and the gable end wall to provide a sealed, insulated attic for housing the HVAC ducts

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Right – Spray foam insulation is sprayed on the underside of the roof deck to provide a conditioned space in this low attic for the HVAC ducts.

Right – Spray foam insulation is sprayed on the underside of the roof deck to provide a conditioned space in this low attic for the HVAC ducts.

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The sealed, insulated crawlspace is a clean, dry location to house the main floor heating ducts and also provides bonus storage space.

The sealed, insulated crawlspace is a clean, dry location to house the main floor heating ducts and also provides bonus storage space.

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This is an example of an insulation pattern for rigid metal ducts that has been measured and cut in a comfortable location before being carried into the attic.

This is an example of an insulation pattern for rigid metal ducts that has been measured and cut in a comfortable location before being carried into the attic.

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Wrong - HVAC duct and flue are too close to wall and will be difficult to properly air seal and insulate around when ceiling is installed.

Wrong - HVAC duct and flue are too close to wall and will be difficult to properly air seal and insulate around when ceiling is installed.

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HVAC ducts, cavities used as ducts, and combustion inlets and outlets may pass perpendicularly through exterior walls but shall not be run within exterior walls unless at least R-6 continuous insulation is provided on exterior side of the cavity

HVAC ducts, cavities used as ducts, and combustion inlets and outlets may pass perpendicularly through exterior walls but shall not be run within exterior walls unless at least R-6 continuous insulation is provided on exterior side of the cavity

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The spray foam-insulated attic provides a temperate place for the ERV ducts, which provide filtered fresh air to every room in the house.

The spray foam-insulated attic provides a temperate place for the ERV ducts, which provide filtered fresh air to every room in the house.

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Step 4. Install insulating sheathing and vertical furring strips on the retrofitted exterior wall; seal around pipe or duct with urethane sealant.

Step 4. Install insulating sheathing and vertical furring strips on the retrofitted exterior wall; seal around pipe or duct with urethane sealant.

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Right – Spray foam air seals and insulates the walls including the walls behind the fireplace and covers the underside of the roof deck of this mixed-dry climate home to provide an insulated attic space for HVAC ducts.

Right – Spray foam air seals and insulates the walls including the walls behind the fireplace and covers the underside of the roof deck of this mixed-dry climate home to provide an insulated attic space for HVAC ducts.

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This Habitat for Humanity builder ordered roof trusses with a 2-foot by 2-foot notch next to the center post then lined the cutout with rigid foam to form an insulated central duct chase to bring the heating and cooling ducts within the conditioned space.

This Habitat for Humanity builder ordered roof trusses with a 2-foot by 2-foot notch next to the center post then lined the cutout with rigid foam to form an insulated central duct chase to bring the heating and cooling ducts within the conditioned space.

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Tuck any extra vapor barrier around and under the insulation and pull it tight to the connecting duct or boot to create a firmer surface to apply tape.

Tuck any extra vapor barrier around and under the insulation and pull it tight to the connecting duct or boot to create a firmer surface to apply tape.

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Spray foam insulation is applied along the underside of the roof deck to provide a conditioned and non-vented attic space for ducts and air handlers.

Spray foam insulation is applied along the underside of the roof deck to provide a conditioned and non-vented attic space for ducts and air handlers.

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This whole house fan is suspended from rafters and connected to the intake grille by a curved insulated duct, greatly reducing vibration and noise in the occupied space

This whole house fan is suspended from rafters and connected to the intake grille by a curved insulated duct, greatly reducing vibration and noise in the occupied space

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HVAC ducts can be encapsulated in 3 inches of closed-cell spray foam, then buried in R-49 of blown fiberglass insulation after the ceiling drywall is installed in the vented attic.

HVAC ducts can be encapsulated in 3 inches of closed-cell spray foam, then buried in R-49 of blown fiberglass insulation after the ceiling drywall is installed in the vented attic.

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Right: This heat pump water heater is installed in a small space so the, intake air is ducted from an adjacent room; the water heater since on a pad of foam insulation and has a good drain line configuration but the waterpipes lack insulation

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The unvented attic is insulated along the underside of the roof deck with 7 inches (R-49) of closed-cell spray foam, providing vaulted ceilings and a conditioned knee wall space for ducting.

The unvented attic is insulated along the underside of the roof deck with 7 inches (R-49) of closed-cell spray foam, providing vaulted ceilings and a conditioned knee wall space for ducting.

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Right - This new sealed attic has 5.5 inches (R-20) of spray foam insulation along the underside of the roof deck providing a conditioned attic space for the heating and cooling ducts.

Right - This new sealed attic has 5.5 inches (R-20) of spray foam insulation along the underside of the roof deck providing a conditioned attic space for the heating and cooling ducts.

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Wrong – These flex ducts are pulled taut, which is correct but they are inadequately supported with straps that are spaced too far apart and are too tight causing pinching of the insulation and turns are sharp rather than gradual.

Wrong – These flex ducts are pulled taut, which is correct but they are inadequately supported with straps that are spaced too far apart and are too tight causing pinching of the insulation and turns are sharp rather than gradual.

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A floor cavity between the first and second floor can provide a conditioned space for HVAC ducts if the rim joists are insulated and air sealed, if sufficient space is available, and if open-web floor joists are used

A floor cavity between the first and second floor can provide a conditioned space for HVAC ducts if the rim joists are insulated and air sealed, if sufficient space is available, and if open-web floor joists are used

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Specially designed roof trusses come with a two-foot by two-foot notch cut next to the center post providing space to install an insulated duct chase inside the home’s conditioned space but above the normal ceiling height.

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The fiberglass insulation stuffed into the large hole around this HVAC duct will not prevent air leakage from the unconditioned basement to the conditioned space above; the large gap should be sealed with a rigid air barrier and caulked or spray foamed.

Fiberglass insulation stuffed into the large hole around this HVAC duct won't prevent air leakage from the unconditioned basement to the conditioned space above; the large gap should be sealed with a rigid air barrier and caulked or spray foamed.

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Side view of an exhaust fan duct installed through an exterior wall showing flashing and air sealing details (the yellow layers are rigid insulation that was installed over the home’s original sheathing before installing new siding).

Side view of an exhaust fan duct installed through an exterior wall showing flashing and air sealing details (the yellow layers are rigid insulation that was installed over the home’s original sheathing before installing new siding).

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Advanced framing techniques including 2x6 walls spaced at 24 inches on center and ladder blocking at wall intersections allow more space for insulation in the wall cavities while open-web floor joists provide space between floors for ducting.

Advanced framing techniques including 2x6 walls spaced at 24 inches on center and ladder blocking at wall intersections allow more space for insulation in the wall cavities while open-web floor joists provide space between floors for ducting.

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Encapsulated Ducts

Video

Video describing air sealing and insulation for encapsulated ducts.

Encapsulated Ducts

Guide

Guide that illustrates how and when to encapsulate ductwork in unconditioned attics, increasing the R-value of duct insulation, mitigating condensation issues, and reducing air leakage.

Diagram of buried ducts

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