Specification

4
6
7
6
4
5
5
3
2
2
2
1
3
4
Zone 4 - Marine
4
Determining your climate zone and building code requirements.
In the northern states and Canada, chances are that building
code mandates a vapor control layer be installed on the
warm side of the insulation. A vapor control layer in northern
climates helps to reduce the moisture diffusion through the
wall assembly and through to the drywall.
Vapor control layers and barriers have different permeance
levels measured in perms and depending on your building
code you may need to install a vapor control layer with
a specic perm rating. In Canada and some northern US
states, a 6 mil polyethylene sheet is commonly used, but
always check with your local building code for guidance.
ASHRAE – history of R-value requirements
The American Society of Heating, Refrigerating and Air
Conditioning Engineers (ASHRAE) is an international society
of technical individuals who provide knowledge to the
building industry on heating, ventilation, air conditioning,
and refrigeration (HVAC&R). The Society developed ASHRAE
90.1, an energy conservation standard that provides the
minimum requirements for energy-efcient buildings.
This standard, or an equivalent, is applied today
in many states for commercial, government and
high-rise building applications. In Canada, look to
the National Building Code and refer to section A-5.3.1.2
for information on condensation and energy conservation
standards.
ASHRAE map of climate zones (above)
Every rating agency has its own maps that divide regions
into thermal or climate zones to tailor codes and standards
to what is appropriate for that particular region.
In Zone 1, Zone 2, Zone 3 and Zone 4 (except Zone 4
Marine), no vapor retarder is required on the interior surface
of insulated wall and oor assemblies while in the northern
states, some form of vapor retarder is likely code mandatory.