Comprehensive Attic Package - Vented to Unvented Attic
Description
Installed correctly, comprehensive vented-to-unvented attic upgrades can significantly reduce utility costs while improving comfort, indoor air quality, and durability of the attic structure.
Checklist
This U.S. Department of Energy checklist includes important specifications that can contribute to a complete and quality installation. All work shall comply with these specifications, all relevant codes and standards, and all manufacturer installation instructions. The contractor shall check each box on the checklist below and sign and date at the bottom to certify the work is completed.
| ▢ | P.1: The attic shall be inspected for water leaks and moisture, structural, or pest damage. A list of all needed repairs shall be provided to the homeowner before attic work begins so remediation can be fully addressed as necessary. |
| ▢ | P.2: If there is active knob and tube wiring present in the attic, the homeowner shall be directed to hire a licensed electrician to inspect the wiring and provide a list of any necessary repairs to the homeowner. The work shall not begin until the homeowner provides written notice that all necessary repairs in the attic are completed. |
| ▢ | P.3: The attic shall be inspected for the presence of any existing HVAC duct or vermiculite attic insulation that may contain asbestos. If asbestos is present, work will stop and the material will be safely removed according to EPA requirements and guidelines. |
| ▢ | P.4: A combustion safety test is recommended to be performed if any natural draft combustion equipment exists in the home to ensure there is no backdrafting or spillage. If performed, any combustion safety issues not addressed by installation measures included in this checklist shall be addressed before proceeding with the installation. |
| ▢ | P.5: All exhaust fan ductwork in the attic shall be inspected for proper installation including no excessive length and sagging, no kinks, and termination to outdoors (i.e., exhaust fans shall not vent directly into the attic). Required modifications shall be identified and included in this scope of work. |
| ▢ | P.6: The contractor shall remove existing attic insulation (insulation at the attic floor) to minimize wintertime condensation risks in the attic. |
| ▢ | P.7: If there is a vapor retarder on the attic floor, it shall be removed to allow proper drying of the insulated assembly. |
| ▢ | P.8: All existing attic ventilation openings including ridge vents, gable vents, and soffit vents shall be closed off with solid sheathing or other weather-resistance material and sealed and patched to match existing exterior finishes (e.g., roofing, siding, or soffit). |
| ▢ | P.9: All wood-to-wood framing joints and penetrations exposed to exterior conditions shall be sealed with caulking or foam. Maximum gap dimensions to be sealed shall be consistent with sealant manufacturer’s specifications. Alternately, if polyurethane spray foam is used, covering or “encasing” these wood-to-wood joints with the spray foam is acceptable. |
| ▢ | P.10: Any existing whole-house fan shall be removed or disconnected from the switch and electric power. The whole-house fan ceiling opening shall be fully patched and refinished to match the existing ceiling (e.g., drywall). |
| ▢ | P.11: Care shall be taken not to block, remove, or disable kitchen or bathroom fan exhaust vents, water heater or furnace flues, radon vent pipes, and plumbing vent pipes. |
| ▢ | P.12: Any heating and cooling and exhaust ducts located in the attic shall be inspected. Any separated or disconnected ductwork other than dryer ducts shall be secured with mechanical fasteners (e.g., screws and clamps). Damaged ducts “compressed duct” restricting air flow or with visual leaks shall be repaired or replaced. Flexible ducts with excessive length shall be cut to proper length to ensure maximum sag is ½ inch per foot. Sharp bends shall be corrected so bends are greater than or equal to one duct diameter radius. All accessible unsealed seams in ductwork shall be sealed with UL-approved mastic, UL 181 tape, or equivalent. |
| ▢ | P.13: All unsupported horizontal heating and cooling duct runs shall be supported with hanger strap or saddle supports that are at least 1.5 inches wide and spaced no more than 4 feet apart, in accordance with the Air Conditioning Contractors of America (ACCA) Manual D and manufacturer’s recommendations. Additional supports shall be provided before and after sharp bends in the ductwork. The maximum permissible sag between supports shall be ½ inch per foot. |
| ▢ | I.1: Exhaust fan ductwork shall be modified as required for the most direct route to the outdoors, with as few bends as possible. To reduce noise, no bends should occur in the first three feet from the fan housing. |
| ▢ | I.2: The exhaust duct outlet vent shall be located on the exterior of the home at least 10 feet from any air inlet and where it does not direct air flow onto a walkway. If the exhaust duct outlet needs to be relocated to meet these requirements, the existing opening shall be closed off with solid sheathing or other weather-resistant materials and be sealed and patched to match existing finishes (e.g., exterior roofing, siding, or soffit). |
| ▢ | I.3: All unsealed exhaust duct seams and connections shall be sealed with UL-approved mastic, UL 181 tape, or equivalent. |
| ▢ | I.4: Where the exhaust fan terminates with a wall cap, verify the presence of a damper that closes when the fan is not operating. If there is none, a damper shall be installed per local building code requirements. |
| ▢ | I.5: All sealants used shall be compatible with their intended surfaces. Maximum gap dimensions shall be consistent with sealant manufacturer’s specifications. |
| ▢ | I.6: Gaps around masonry chimneys, flues, or combustion appliance vents shall be sealed with sheet metal and high-temperature rated caulk or foam. Insulation dams shall be constructed around chimneys, flues, and combustion appliance vents as needed with combustion clearances using heat-safe materials in accordance with local building code requirements. A masonry chimney typically requires a 2-inch clearance to combustibles; a Type-B (double wall) gas vent pipe typically requires 1-inch clearance to combustibles. The air barrier may be metal that is air sealed using high-temperature rated caulk. Cellulose and fiberglass insulation are considered combustible. Local building code may allow mineral wool to contact a masonry chimney but not a metal gas vent. |
| ▢ | I.7: A continuous airtight seal consisting of caulk, liquid membrane coating, mastic, spray foam, and/or equivalent shall be applied at seams, cracks, joints, and edges, and around all penetrations and vents at all sheathing at roof and vertical gable walls to the exterior. |
| ▢ | I.8: If the existing attic extends over unconditioned spaces (garages, exterior porches), this area must be separated from the conditioned attic with insulation and an air barrier. Typical practice is to build a stud wall with sheathing at this conditioned attic boundary, insulate the wall, and provide air barrier detailing at the perimeter and penetrations. |
| ▢ | I.9: Insulation that meets or exceeds prescriptive R-values specified for roof/ceiling insulation by local building code requirements for new construction shall be installed at all roof surfaces with less than 2% gaps, voids, and compression. |
| ▢ | I.10: Insulation that meets or exceeds prescriptive R-values specified for above-grade walls by local building code requirements for new construction shall be installed at all gable and other wall surfaces adjoining the exterior with less than 2% gaps, voids, and compression. |
| ▢ | I.11: All local building code requirements for air-permeable and air-impermeable insulation at the roof sheathing shall be fully met (IRC §R806.5 or equivalent). |
| ▢ | I.12: If plastic foam insulation (e.g., spray foam) is used at the roofline, all local building code requirements for a fi re ignition barrier at the insulation surface exposed to the attic shall be fully met. |
| ▢ | R.1: In Hurricane-Prone Regions, two-part closed-cell polyurethane spray foam is recommended at all points where roof decking meets rafters and at seams in the roof deck. This upgrade can increase roof resistance to uplift by up to 300%. |
| ▢ | R.2: In Hurricane-Prone Regions, it is recommended that gable walls be reinforced and two-part closed-cell polyurethane spray foam be applied to help increase structural resistance to collapse in high-wind events. Additional guidance on reinforcement can be found in FEMA documentation (see Wind Retrofit Guide for Residential Buildings FEMA P-804). |
| ▢ | I.13: All accessible duct leaks, connections, and plenums shall be sealed with UL-approved mastic, UL 181 tape, or equivalent (e.g., aerosol sealant) used in strict accordance with manufacturer’s instructions. |
| ▢ | I.14: Duct boots located at the attic-ceiling interface shall be sealed to finished surfaces with caulk, spray foam, or other approved sealants consistent with sealant manufacturer specifications. |
| ▢ | I.15: If the air filter is installed in a filter box attached to an air handler located in the attic, the filter access panel should be fitted with an air-tight gasket, and a MERV 8 or higher filter shall be installed in the filter rack. |
| ▢ | C.1: Unvented attics shall be supplied with air for space conditioning per local building code requirements. If not addressed by local building codes, for unvented attics with only air-permeable insulation in IECC Climate Zones 1, 2, and 3, HVAC supply and return grilles shall be added to the attic that provide a minimum air flow rate of 1 CFM/20 ft2 of attic floor area where ducts are accessible to the attic. Where HVAC supply or return ducts are not accessible to the attic, a supply fan shall be provided between the attic and living space below that provides an air flow rate of 1 CFM/20 ft2 attic floor area when the HVAC system is operating. |
| ▢ | C.2: The owner shall be informed that, at next replacement of HVAC system, increased system capacity may be needed to maintain comfort, especially if new conditioned attic volume is converted to living space. Alternatively, if no new living space is created a HVAC load calculation should be performed to resize equipment accordingly. |
| ▢ | C.3: The home shall be inspected for the presence of a whole-house ventilation system. If one is present, the actual air flow shall be tested and verified to meet a target ventilation rate based on house size as follows: 50 cfm for up to 1,500 ft2, 70 cfm for 1,501 to 2,500 ft2, and 100 cfm for over 2,500 ft2. If the home has no whole-house ventilation system, or if the existing system does not meet the target ventilation rate, recommendations shall be made to the homeowner to either install a new system or repair the existing system to meet the target ventilation rate. |
| ▢ | C.4: If an exhaust vent was installed in a wall, the wall cap damper shall be checked to ensure it is operating correctly. |
| ▢ | C.5: In EPA Radon Zone 1, a radon test kit shall be provided to the homeowner at the completion of the work with a recommendation to initiate a radon remediation strategy if post-retrofit radon measurements exceed EPA acceptable levels (see https://www.epa.gov/radon). |
| ▢ | C.6: After completion, a combustion safety test shall be performed if any natural draft combustion equipment exists in the home, to ensure there is no backdrafting or spillage. After attic air sealing, a natural draft furnace or water heater located in the home may no longer have sufficient combustion air. Recommendations shall be made to the homeowner to install direct-vent equipment at the time of replacement for any natural draft combustion equipment. |
Comprehensive Attic Package - Vented to Unvented Attic Background
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Trust Matters: Inform homeowners how your work conforms to this world-class expert guidance. Recommend they visit the DOE website as evidence these are indeed official best practices.
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Experiences Matter: Provide visual evidence contrasting the difference between poor and high quality work such as infrared images; pre- and post-energy bills; short and long warranties; and simple charts and graphics depicting performance advantages.