BASC Search | Building America Solution Center

Collars that are specifically made for flexible duct have a raised bead to prevent the duct from slipping off

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Form sheet metal shield around pipe keeping 3-inch clearance

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Fiberglass duct board typically comes in sheets 4 foot wide by 10 foot long

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Wrong: Ducts are not laid across the lower truss cords or ceiling, but are hung from the rafters by straps. As a result, ductwork is not buried

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Wrong: Ducts are held from the rafters with strapping and a large beam prevents ducts from properly lying on the ceiling plane

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Install wood framing cross pieces in the attic rafter bays on each side of the duct chase

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Two pieces of flex duct are spliced together with a metal sleeve, nylon draw bands, mastic, metal tape, and more mastic

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Seal seams in fiber board ducts with out-clinching staples, UL-181A-approved tape, and mastic

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Wrong: This exhaust fan duct is too long and terminates in the attic instead of going through the roof and it is improperly supported; it needs straps all along its length to prevent sagging.

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Hand tools for cutting fiber board sheets include a knife, straight edge, and color-coded edge-cutting tools

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Right - The rigid metal HVAC ducting is installed between the floor joists rather than in an unconditioned attic or crawl space to minimize heat loss.

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Right – R-25 of open-cell spray foam lines this new home’s attic ceiling, to protect HVAC ducts from heat and cold.

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Right - Open-cell polyurethane spray foam to R-28 on underside of roof turns new attic into conditioned space for HVAC.

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Cut fiber board with a red V-groove tool and a gray shiplap tool to create mitered corners and a shiplapped edge for duct sections

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New Whole-House Solutions Case Study: Pine Mountain Builders, Pine Mountain, Georgia

Case Study

Case study describing a builder in Georgia that designs energy-efficient homes for a green community, yielding homes with HERS scores as lowas 59 and electric bills as low as $50 a month.

The inner liner of the flex duct is fastened to the collar with a tension tie, the connection is sealed with mastic, then the outer layer is pulled over and sealed with mastic or foil tape (Steven Winter Associates 2013).

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No Ducts or Air Handlers Located in Garage

Guide

Guide describing how to design HVAC systems to be located within the conditioned space of the home, either in a utility closet or in an attic, basement, or crawl space.

Right: Ductwork is installed in direct contact with lower truss cords. In this picture the main trunk is laying on the truss cords and branch ducts are temporarily held with strapping across truss cords. Ducts are well sealed with mastic

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Transfer Grilles (1)

Video

Video describing how to install transfer grilles.

New Whole-House Solutions Case Study: Insight Homes: Deep Creek, Seaford, Delaware

Case Study

Case study describing a home builder that has refined its home designs to achieve HERS scores of 49 to 56 on 40 to 70 homes per year.

No Sweat, BSI-094

Reference

Guide providing information on controlling attic ductwork sweating.

Energy Code - Module 7: Ducts, HVAC, Hot Water, and Lighting

Presentation

Webinar that will explain mandatory and prescriptive requirements related to duct installation, insulation, sealing, and testing, as well as requirements for heating, cooling, and hot water systems and controls.

Venting Vapor, BSI-088

Reference

Guide providing information on controlling attic ductwork sweating.

Small Commercial Building Fact Sheet - Building Envelope

Reference

Fact sheet describing building envelope performance measures applicable to residential and small commercial construction.

Still Placing Ducts in the Attic? Consider Burying Them

Reference

Information sheet about buried ducts.

Ducts in Interstitial Floor Framing

Guide

Guide for designing and installing interior ducts in an interstitial floor cavity in new and existing homes.

Design Options for Locating Ducts within Conditioned Space

Presentation

Presentation with technical training covering several possible approaches to locating ducts within the home’s air and thermal barriers, and then dig into design considerations and details for the spray foam encapsulation approach.

Evaluation of Retrofit Delivery Packages

Reference

Report evaluating opportunities to improve and streamline delivery of residential retrofit measures.

Buried and Encapsulated Ducts, Jacksonville Florida

Reference

Reference investigating the strategy of using buried and/or encapsulated ducts to reduce duct thermal losses in residential buildings.

Sealing Duct Boots to Floor or Drywall

Guide

Guide describing how to air seal around duct shafts and flues installed through ceilings, walls, and flooring in new and existing homes.