Chapter 6 CM&M
Which of the following materials has the lowest perm rating?
1/16 in thick aluminum sheet
Although leakage and diffusion are two separate mechanisms, their impact on the performance of the envelope is the same.
True
In warm climates, such as Climates zones 1 to 3, the vapor retarder may be omitted in wood or cold-formed steel (CFS) framed assemblies if the interior wall finish is a latex painted gypsum board
True
Soffit vents alone are not adequate to provide attic ventilation
True
The use of membrane or liquid air barriers is required in the envelope of all heated or cooled buildings.
True
A wrap-type, membrane air barrier is available in many varieties, but in all of them, it is made from
a perforated plastic sheet
Ventilation of an attic space is generally considered important in
all climates
An ice dam is likely to occur
at the eave of a sloping roof
A material whose perm rating in the U.S. system of units is 0.5 perm is a
class II vapor retarder
Per the international building code, class I vapor retarder should only be used in wood or cold-formed steel (CFS) frame assemblies in
climate zone 5,6,7,8 and marine 4.
Liquid-applied air barriers and membrane air barriers can be used interchangeably
false
The greater is the thickness of a given material, the greater is its perm rating.
false
A membrane air barrier is
fastened to sheathing on site, adhered to sheathing on site, factory-adhered to sheathing panels.
During the heating season, the vapor pressure of the inside air in a typical dwelling in the northern United States is
greater than the outside
Perm rating is a property that measures
how effectively water vapor diffuses through the material.
Leakage and diffusion of a gas (such as air or water vapor) through a building envelope are two different mechanisms because?
leakage occurs through holes, cracks, and openings in the envelope, while diffusion occurs through the body of envelope component or its material.
The dew point of air is always
less than or equal to the air temperature
Breathability of an air barrier refers to its
none of the above
a vapor retarder is perforated so that
none of the above
an air barrier is generally placed
on the exterior face of an exterior sheathing
in addition to being a barrier to the passage of air, an air barrier must also unction as a barrier to the passage of
rainwater
The primary purpose of sealants and weatherstripping is to
reduce air leakage through the envelope
When gable vents are provided to ventilate an attic space,
soffit vents are also necessary
Air leakage through a building envelope is a function of
the area of holes, cracks, and openings in the envelope, wind speed, and the inside-outside air temperature difference.
During the heating season, the vapor flow in conditioned buildings is generally from
the inside to the outside of the envelope
Concealed condensation occurs inside an envelope assembly during a heating season if
the interior vapor can permeate into the assembly but cannot exit it, the value of the assembly is high.
In hot humid climates, the vapor flow in conditioned building is generally from
the outside to the inside of the envelope
an air barrier is generally used on
the walls
Building assemblies are generally more vapor permeable than air permeable because
vapor pressure differential between the inside and the outside air is much greater than the corresponding air pressure differential.
