1) General Air‑Barrier & Insulation Preparation

• Provide a continuous, sealed air barrier wherever a conditioned surface adjoins an unconditioned space (exterior walls, walls between garage and home, raised floors, ceilings below attic, etc.).
• Demonstrate compliance by one of the following:
  • Material path (ASTM E2178): air permeance ≤ 0.004 cfm/ft² @ 0.3 in. w.g.
    Examples: fully‑adhered air/water‑barrier membranes; liquid‑applied air barriers; closed‑cell SPF ≥ 2 in. or open‑cell SPF ≥ 5.5 in. when used as the air barrier; taped/sealed rigid foam boards (XPS, polyiso, foil‑faced urethane).
  • Assembly path (ASTM E2357/E1677/E1680/E283): leakage ≤ 0.04 cfm/ft² @ 0.3 in. w.g.
    Examples: taped sheathing systems (OSB/plywood/gypsum) with sealed joints & penetrations; integrated WRB sheathing systems; housewrap with taped seams & flashings; SIPs/ICFs with sealed joints.
  • Whole‑building test (ASTM E779): envelope leakage ≤ 0.40 cfm/ft² @ 0.3 in. w.g. (blower‑door pass at or below threshold).
• Seal all penetrations through walls/roof/floor (pipes, wires, ducts, vents, boxes, fans).
• Meet CF1R R‑values for every insulated assembly; install strictly per manufacturer instructions and retain labels/data sheets/coverage charts for the HERS rater.
• Avoid Thermal bridges in structural members (tie‑downs, steel studs, straps, shear/bracing): insulate between the exterior air barrier and metal to reduce bridging and document details on plans where applicable.

2) Raised Floors Over Unconditioned Spaces (or Separate Dwelling Units)

• Seal floor gaps/penetrations and seal chases at floor level with rigid, sealed covers.
• Glue/seal subfloor panel edges to form a continuous airtight subfloor air barrier.
• Install insulation in full contact with the subfloor. Use hangers ≤ 18 in. apart; do not compress batts. Netting/mesh is acceptable if cavities are fully filled and in contact with the subfloor.
• If crawlspace access is from conditioned space, install an airtight, insulated access hatch (exterior access preferred).

3) Exterior Walls Adjacent to Unconditioned Space

• Seal top & bottom plates, rim/band joists, around doors/windows, and all penetrations to outdoors/attic/garage/crawlspace.
• Electrical boxes (including knockouts) that penetrate the air barrier are sealed.
• Six‑sided contact: insulation touches top, bottom, back, left, right, and the future interior finish plane—with no gaps, voids, or compression.
• Deep cavities (double walls, bump‑outs): install a secondary air barrier in contact with the insulation so the insulation fully fills the framed volume.
• Snug fit around wiring/plumbing; insulate between exterior air barrier and metal tie‑downs/shear panels.
• Hard‑to‑access cavities (corners/intersections) insulated before exterior sheathing or stucco lath.
• Behind tubs/showers/fireplaces/stairwells on exterior walls: install insulation to CF1R R‑value plus an interior air barrier.
• Single‑member window and door headers: insulate to R‑3 (2×4) or R‑5 (others) unless exempt (header flush with wall thickness and wall has ≥ R‑2 overall).
• After insulating: all insulated walls (including kneewalls & skylight‑well walls) have interior & exterior air barriers; seal gypsum to top plate (rim joists excepted).
• Seal exterior bottom plates to the floor.
• Seal rim/band‑joist gaps and openings.
• Seal the exterior wall air barrier to the top & bottom plate in each stud bay.
• Seal fan‑exhaust outlets/dampers to the exterior wall air barrier.

4) Ceilings Adjacent to Unconditioned Spaces

• Provide a continuous ceiling air barrier; seal openings into walls/drops/chases/double walls.
• Seal top‑plate penetrations (interior & exterior walls).
• Seal fire‑sprinkler penetrations per manufacturer instructions.
• Seal all fixtures (registers, lights, fans, alarms, boxes) to drywall; if direct sealing isn’t possible, build a secondary air‑barrier box.
• Recessed fixtures that penetrate to unconditioned space are IC/AT‑rated and covered with insulation to meet the ceiling R‑value.
• Dropped ceilings: install sealed hard covers or insulate the bottoms & sides per CF1R.
• Seal vertical chases & soffits at the ceiling level.
• Chimneys/flues: provide sheet‑metal collar at ceiling; seal to flue and surrounding framing with fire‑rated sealant; keep clearances ≥ 1 in. (double‑wall) and ≥ 6 in. (single‑wall); collar height ≥ insulation depth; insulation in contact with collar.
• Attic access: airtight with mechanical compression (latches/screws); insulate to ceiling R‑value; build a dam around the opening to full insulation depth.
• Extend ceiling insulation to the outside face of the exterior wall and maintain direct contact with the ceiling air barrier.
• Insulate external surfaces of steel studs, steel‑framed kneewalls, skylight shafts, and gable ends.

5) Roof Deck & Attic Insulation

Unvented Attics

• The roof sheathing is the air barrier; seal penetrations in the roof deck and gable ends.
• Insulation is in full contact with the roof sheathing.
• If using air‑permeable insulation, seal & insulate gable ends like exterior walls (including an interior air barrier).

Vented Attics

• Maintain required eave ventilation; do not obstruct vents.
• Install eave baffles & dams to prevent air movement under or into the ceiling insulation.
• Attic access is insulated to the ceiling R‑value and permanently attached; provide an insulation dam around the access.
• Loose‑fill verification: install depth rulers (match brand/type), evenly distributed at 1 per 250 ft², legible with inches & corresponding R‑value.

High‑Performance Vented Attics

• Insulation in full contact with roof sheathing and supported to prevent sagging.
• Batts between trusses are acceptable with minimal gaps/voids from truss members.
• Gable end walls need not be insulated in this configuration.
• Provide roof‑deck insulation over any conditioned space or HVAC ducts across the entire roof deck, including over unconditioned areas (e.g., garage/porch) unless those attics are duct‑free and isolated from other attics by a sealed air barrier.

6) Cantilevered Floors

• Install sealed blocking between joists where a rim joist would normally be.
• Install exterior sheathing to the bottom of the cantilever to create a continuous air & weather barrier.
• Insulate both sides of the blocking and fill joist cavities to the required R‑value before closing.
• Seal gaps/penetrations; any recessed lights in the cantilever are IC/AT‑rated and sealed to the sheathing.

7) Floors Above / Adjacent to Garages

• All penetrations in the subfloor above the garage follow raised‑floor air‑barrier requirements.
• Option A — Air barrier at garage ceiling: seal perimeter edges of the garage ceiling (typically drywall); seal all plumbing/electrical/mechanical penetrations; for open‑web trusses, add airtight blocking on all four sides of the garage perimeter; insulation may be placed on the garage ceiling; insulate the subfloor perimeter above.
• Option B — Air barrier at subfloor: seal the band‑joist at the garage‑to‑conditioned transition; seal subfloor seams & penetrations; place insulation in direct contact with the subfloor under the conditioned space.

8) Skylight Shafts & Attic Knee Walls

• Completely enclose skylight shafts & kneewalls with vertical and horizontal framing, including top & bottom plates.
• Insulate all six sides; insulation in full contact with the air barrier; unless SPF is used, also in full contact with the interior finish.
• Trim batts to fit tightly around flat 2× members and other obstructions.
• Provide solid, sealed blocking at the bottom, top, left, and right of kneewalls.

9) Attached Porches & Special Framing

• Fully insulate the exterior wall at the porch‑roof intersection above, below, and behind the roof line.
• Where truss framing is used, install airtight blocking at the top & bottom of each wall/roof section and insulate the blocking.
• Provide a continuous exterior wall air barrier where the attic/porch framing interfaces with conditioned space.

10) Spray Polyurethane Foam (SPF)

• Confirm the certified R‑value per inch; total R = (tested R/in.) × (installed thickness).
• Verify installed thickness meets CF1R in ≥ 6 random locations for each surface type (floors, walls, ceilings).
• Fully adhere foam to framing/sheathing; where multiple lifts are applied, ensure each lift bonds to the substrate and prior lift.
• Minimum thickness in air‑barrier zones: closed‑cell ≥ 2 in., open‑cell ≥ 5.5 in.
• Open‑cell SPF: surface depressions ≤ ½ in. and ≤ 10% of the insulated area; 2×4 cavities fully filled.
• Recessed fixtures: do not spray SPF directly unless permitted by the fixture manufacturer. Otherwise, cover with ≥ 1.5 in. mineral‑fiber insulation or enclose in a manufacturer‑approved box (e.g., 18‑ga sheet metal or ½‑in. gypsum).
• Observe manufacturer restrictions near flues, vents, and recessed fixtures.