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Duct insulated with a minimum of R-8 insulation

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Ducts Buried in Attic Insulation and Encapsulated

Guide

Guide describing approaches to burying and encapsulating ducts in unconditioned attics to increase the overall R-value of duct insulation.

Second layer of rigid insulation is adhered with foam

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Ducts Encapsulated in Spray Foam and Buried in Attic Insulation

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Video describing various ways to bring HVAC ducts installed in an attic within the thermal envelope of the home by insulating the attic or by covering the ducts with spray foam and burying them in fibrous insulation.

Spray foam insulation used for raised ceiling duct chase

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Spray foam insulation used for raised ceiling duct chase.

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The attic duct chase insulated and sealed to the attic floor with spray foam

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Right: Ducts are completely buried beneath insulation to the depth specified in the plans

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The duct for this exhaust fan is properly routed through the roof and the duct is insulated

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Wrong: Ducts are held above the ceiling plane with strapping to provide a good angle into top-entry boots. Once the ceiling insulation is added, this duct will protrude from the ceiling insulation and will not be buried

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Right- This flue pipe has been air sealed with sheet metal and fire-rated caulk and an insulation dam has been constructed to keep insulation from touching the hot flue pipe

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Form an insulation dam of heat-resistant insulation with at least 3 inches of clearance around a flue pipe in the attic after air sealing around the pipe with sheet metal and fire-rated caulk or canned foam

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Standard 2 in. by 4 in. stud secures duct chase - made of rigid insulation in this example

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Wrong: Ductwork is not fully encapsulated with ccSPF insulation. The duct jacket is still fully visible at sections of the duct

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Buried ducts are laid on the floor of a vented attic then covered with spray foam and blown attic floor insulation

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Wrong: open wall cavity connected to this return air plenum is allowing cellulose attic insulation to be pulled into the furnace

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Form an insulation dam of sheet metal around a flue pipe in the attic after air sealing around the pipe with sheet metal and fire-rated caulk or canned foam

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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

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Encapsulated Ducts

Video

Video describing air sealing and insulation for encapsulated ducts.

Compact Buried Ducts in a Hot-Humid Climate House

Reference

Report on heating and cooling air-distribution ducts that are insulated, installed close to the ceiling in a vented attic and covered with attic insulation to minimize energy loss.

Ducts in Raised Ceiling Sections

Guide

Guide describing method for designing and installing ducts in a raised ceiling chase.

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.