How To Seal Air Leaks During Construction Section 2

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How To Seal Air Leaks During Construction -
Section 2
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Pre-insulation Building Envelope Sealing

• Inspect for readiness
• Are windows and doors installed?
• Electrical, plumbing, etc. installed?
• Check for trouble spots
• Soffits, chases, needed blockers, cantilevers
• Sheathing, party walls, bathtubs

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The procedure

• Install blocking and seal in place
• Foam
• Outer walls first, then as needed on interior
  walls
• Windows (if gap is tight, use caulk)
• Basement
• Band joist
• Caulk
• Top and bottom plates, trimmers, multiple studs,
  corners
• Windows and headers
• Post-inspection

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This stage of sealing should be completed after
all mechanical rough-ins are completed and prior
to exterior insulation
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Knee and high (pony) walls

• Typical Installation - exposed/hanging batts
• Treat like exterior wall - enclose all sides

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Sheathing

• Vertical cavities should be sealed on all six
  sides
• (Attics side of knee wall)
• Garages should be sealed prior to air sealing

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Install blocking to stop movement of outside air
Seal

• From attic side, rigid foam board sealed at edges
• Plumbing and duct chases, sealed at attic and in
  basement
• Fireplace chases - using fire rated material -
  typically builders responsibility
• Behind bathtubs on exterior walls

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Blocking and draft stops

• Stops air movement, encloses insulation

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Attic bypasses

• Connection from attic to house via various
  pathways

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Framed floors

• Floor joists
• - TJI, BCI, etc
• - Wood I beam
• Floor Trusses
• - Engineered truss used
• for floor support
• Rim/Band Joist

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Cantilevers, overhangs, bays

• Framed floors that overhang the foundation or
  lower floors

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Problems createdBy cantilevers

• Improper blocking of rim
• - use I joists - gaps, air leaks
• No insulation
• Lack of any air sealing - cold floor system

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Sheathing Seams

• Top and bottom of the sheathing sealed to plates
  with foam
• All vertical seams sealed on both sides of stud
  where seam is.
• All vertical corners sealed with foam or caulk.
• Around doors and windows

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Electrical and Plumbing Penetrations

• Between conditioned and unconditioned-typically
  with foam
• Through top and bottom plate
• Through return duct work
• Horizontal penetrations on exterior walls
• Outlet, switch boxes, cable boxes, etc. on
  outside walls.

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Sealing Rim and Band Joist

• Sealed to wooden plate
• Wood plate to masonry wall may require sealing
  (should have adhesive)
• Band joists between floors where wood meets
• Make sure band is continuous install blocking
  as needed
• Horizontal penetrations

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Windows

• Minimize air movements between rough frame and
  window frame
• Foam to sheathing use gun or wand (do not
  overfill)
• Seal areas less than ¼ with caulk
• Closed cell foam rod around window if needed

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Framing

• King studs to jack studsat windows and doors
• Bottom or base plate to sub floor
• Between double top plates
• Corners - wood to wood with foam or caulk

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Method - continued

• Go to interior walls
• Seal where air will move between conditioned and
  unconditioned areas
• Pipe, wire, duct work - Horizontal and Vertical

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Attic Sealing

• Interior top plates and nailers to drywall
• Exterior top plates to drywall where accessible
• Penetrations - wires, plumbing, etc.

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Light Fixtures

• Electric boxes to attic
• Base of recess lights to drywall
• Recommended to builder that vented recessed
  lights be modified to make air tight

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Other Items

• Whole house fans - make tight seal with cover
• Attic hatches, pull down stairs