Figure 1: Raised Top Plate

Figure 2: T-Wall Options that Allow Insulation

Advanced framing details provide a much more continuous insulation system than traditional framing techniques and prevent insulation voids that can result in moisture problems.

Attic insulation should extend over the top of exterior walls without blocking air flow from the soffit vents. This can be done with a raised top plate or raised heel truss to increase the roof height at the eave. (See Figure 1)

Exterior walls with headers over door and window openings should be framed to include insulation in the headers; double header lumber can be placed on the exterior side to leave space for rigid insulation on the interior side. Various methods have been developed to provide continuous insulation in exterior wall corners and at T-walls (where an interior wall intersects an exterior wall), which are normally blocked by framing lumber. (See Figure 2)

The biggest insulation gaps in the thermal envelope are windows and doors. Choose Energy Star-labeled units.

Insulating and sealing attic access doors over conditioned space is particularly important. If possible, locate the attic access in an unconditioned space and include a lock on it for security. Various types of attic access door covers are now commercially available to cut air leakage and provide some insulation.

Insulated doors have a skin and insulating foam core, creating a much higher R-value than a solid wood door (about R-4). Steel-skin doors are economical, durable and efficient. Fiberglass-skin insulated doors can be stained and have the look of genuine wood with many beautiful styles suitable for front entry doors.

Glass in both windows and doors should be insulated (two layers with an air space) and low-e with framing of wood, vinyl, composite material or metal with a thermal break.

Related article:
Insulation Systems with Good 'Whole Wall' R-values