Know Your Air Barrier Insulation Installation and Whole-House Ventilation Best Practices

Evil Knievel once said “I love the feeling of the fresh air on my face and the wind blowing through my hair.” Of course, he might not have felt that way if he were sitting in the living room of his house! Residential air barrier insulation is key in stopping those interior breezes and leaks.

Robert de Sousa, Energy Codes & Standards Specialist, from Performance Systems Development and working in cooperation with the Mass Save Energy Code Technical Support Program, presented the Residential Air Barrier & Insulation Installation and Whole-House Mechanical Ventilation: Options for Code Compliance Seminar on December 5th before the EM NARI dinner meeting.

6E9C3125rt FBWhile the general requirements for code compliance refer to new construction, Mr. de Sousa recommends these as best practices for remodelers whenever possible:

  • A continuous air barrier shall be installed in the building envelope;
  • The exterior thermal envelope contains a continuous air barrier;
  • Breaks or joins in the air barrier shall be sealed;
  • Air-permeable insultation shall not be used as a sealing material.

The seminar covered energy code compliance for the framing inspection and insulation inspection for ceilings and attics, walls, windows, skylights and doors, rim joists, floors (including above garage and cantilevered floors), crawl space walls, garage separation, shower or tubs on exterior walls, electrical and phone boxes on exterior walls, and concealed sprinklers.

Mr. de Sousa recommended batt insulation should be cut neatly to fit around wiring and plumbing in exterior walls, with special care not to compress insulation. Additional areas of concern for mechanical rough-in inspections include shafts, penetrations and HVAC register boots. Final inspections would include that recessed light fixtures installed in the building thermal envelope should be sealed to the drywall. Access openings, drop down stairs or knee wall doors to unconditioned attic spaces should all be sealed as well.

“Use what is recommended by the manufacturer,” said Mr. de Sousa. “Code enforces the manufacturer’s directions on products.” Mr. de Sousa is a big proponent of spray foam as an air and vapor barrier. However, he also recommends products that allow the house to dry when moisture does get in.


As our homes are being built tighter, contractors must balance the air flow in and out of houses with mechanical ventilation. Remember “built tight and ventilate right.” Why?

  • To supply fresh air without relying on occupants opening windows
  • To dilute pollutants
  • To control moisture
  • To prevent inadequate airflow and create healthier indoor environments

Basically whole-house ventilation systems control the quantity and in some cases the quality of the air in the house. To comply, there must be continuously operating ventilation by:

An exhaust only system (can include bath and kitchen fans)

  • A supply only system
  • A balanced exhaust and supply system

Mr. de Sousa believes a balanced HRV/ERV system is the best practice, although it can be costlier to install and more advanced planning is involved. Abenefit of having an air supply source for ventilation – sometimes tied into the HVAC system – is knowing the air is coming from a clean, outside source. Another benefit of tying into the HVAC system is that the incoming air is filtered and heated or cooled. Leaving Evil Knievel to get the wind in his hair by jumping his motorcycle over cars rather than through his leaky house.

BALANCED MECHANICAL VENTILATION WITH HRV ERVMECHANICAL VENTILATION WHOLE HOUSE BALANCEDFor more information on Mass Save Energy Code Technical Support in MA call 855-757-9717 or email Information and forms for downloading is also available on the Mass Save website:

Thank you to Robert de Sousa, Energy Codes & Standards Specialist, from Performance Systems Development for presenting the Residential Air Barrier & Insulation Installation and Whole-House Mechanical Ventilation Seminar.

Also, thank you to Marvin Windows for sponsoring our seminar.

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