ASHRAE Journal - July 2020 - 59

FIGURE 14 Wood frame assembly with exterior insulation and interior cavity insulation with brick or stone veneer and an interior vapor control layer.

Applicability
OK Cold and very cold regions.
NO Hot-dry, hot-humid, mixed-dry, mixed-humid, marine and subarctic/arctic regions.
NO Interior climate Class III buildings such as hospitals, museums and swimming pool enclosures.
Description This wall is a variation of Figure 12, but with an interior vapor control layer. This wall
has a combined air/vapor/water control layer at the exterior sheathing, inboard of continuous exterior
insulation. The sheathing can be non-paper-faced exterior gypsum, plywood, fiberboard or oriented
strand board. This wall assembly will dry from the vapor control layer inward and will dry from the vapor
control layer outward.
Drainage Cavity Hydrostatic pressure is controlled by providing a drainage space behind the cladding. The
ideal solution is to decouple the exterior brick veneer (a "reservoir" cladding) from the wall assembly with a
ventilated and drained cavity. The cavity behind the brick veneer should be at least 1 in. (25 mm) wide and
free from mortar droppings. It must also have air inlets ("weep holes") at its base and air outlets ("weep
holes") at its top to provide back ventilation of the brick veneer.
Exterior Insulation Vapor impermeable (foil-face polyisocyanurate) or vapor semi-impermeable
(extruded polystyrene) acceptable.
Water Control Layer Combined air/vapor/water control layer at the exterior sheathing. Can be fully
adhered sheet membrane, trowel-on or spray-applied coating, mechanically attached sheet or integral
water control layer within the sheathing.
Air Control Layer Combined air/vapor/water control layer at the exterior sheathing.
Vapor Control Layer (Exterior) Combined air/vapor/water control layer at the exterior sheathing;
vapor-impermeable layer at exterior of wall.
Vapor Control Layer (Interior) and Condensation Control This wall assembly has an interior vapor
control layer; therefore, the wall assembly cannot dry to the interior. Nor can this wall assembly dry to the
exterior. Therefore, this wall assembly is limited to interior climate Class I and II buildings, and is limited
to cold, very cold and colder hygrothermal regions.
Thermal Control Layer Stud bay cavity insulation and exterior rigid insulation.
FIGURE 15 Wood frame assembly with exterior insulation and interior cavity insulation with brick or stone veneer and a smart interior vapor control layer or kraft-faced cavity insulation.

Applicability
OK Marine, cold, very cold and colder hygrothermal regions.
OK All rain exposure zones and interior climate Classes I and II.
NO Interior climate Class III buildings such as hospitals, museums and swimming pool enclosures.
Description This wall is a variation of Figure 14, but with a variable permeance ("smart") vapor control
layer or kraft-faced batt insulation (also a "smart" vapor control layer). This wall is designed to dry to the
interior. The sheathing can be non-paper-faced exterior gypsum, plywood, fiberboard or oriented strand
board.
Drainage Cavity Hydrostatic pressure is controlled by providing a drainage space behind the
cladding. The ideal solution is to decouple the exterior brick veneer (a "reservoir" cladding) from the wall
assembly with a ventilated and drained cavity. The cavity behind the brick veneer should be at least 1 in.
(25 mm) wide and free from mortar droppings. It must also have air inlets ("weep holes") at its base and
air outlets ("weep holes") at its top to provide back ventilation of the brick veneer.
Exterior Insulation Vapor impermeable (foil-face polyisocyanurate) or vapor semi-impermeable
(extruded polystyrene) acceptable.
Water Control Layer Combined air/vapor/water control layer at the exterior sheathing. Can be fully
adhered sheet membrane, trowel-on or spray-applied coating, mechanically attached sheet or integral
water control layer within the sheathing.
Air Control Layer Combined air/vapor/water control layer at the exterior sheathing.
Vapor Control Layer (Exterior) Combined air/vapor/water control layer at the exterior sheathing;
vapor-impermeable layer at exterior of wall.
Vapor Control Layer (Interior) and Condensation Control This wall assembly has a variable
permeance ("smart") vapor control layer or kraft-faced batt insulation (also a "smart" vapor control
layer). This layer changes its vapor transmission based on interior relative humidity. It, therefore, allows
inward drying during the summer or if the wall cavity becomes wet from exterior sources. Even with
inward drying, this wall assembly should be limited to interior climate Class I and II buildings. Despite
the effectiveness of the variable permeance interior vapor control layer, this wall assembly should still be

limited to marine, cold, very cold and colder hygrothermal regions.
Thermal Control Layer Stud bay cavity insulation and exterior rigid insulation.
J U LY 2 0 2 0

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