As home energy readers know venting attics in hot humid climates brings a great deal of moisture into the structure see conditioned attics save energy in hot climates he may june 97 p.
Attic insulation problems in cold climates.
In the winter it reduces heat loss from convective looping and wind washing.
However in cases where a vapor drive is consistently moving in one direction such as cold storage applications or swimming pools it is prudent to conduct hygrothermal modeling or calculations to determine if the proposed design is right for the application.
Though the loose fill version does lose some effectiveness at very cold temperatures this not a problem for much of california.
In the summer it reduces heat gain by reducing attic insulation top surface temperature.
In typical construction and climates building code tables can be followed when using spf as an insulation and air seal.
Find the fiberglass roll insulation with the best r value for your particular climate and attic.
R value is a measure of insulation s ability to resist heat traveling through it.
Standard fiberglass batts and blankets are the best attic insulation because they effectively slow the spread of heat and cold.
What is less well understood is that venting causes many problems in cold dry climates as well.
In this case there were two problems.
To repeat the laws of physics tell us that condensation can not occur if the water vapor is prevented from coming in contact with a surface that is cold enough for the water to condense.
For cold climates loose fill fiberglass insulation is the best as it has an r value of 60.
Loose fill fiberglass is also a great solution because it s lightweight.
Installing a perforated radiant barrier directly on top of attic insulation increases winter and summer efficiencies in mixed and cold climates.
Also in very cold climates it is better to allow soffit to ridge venting between the insulation and roof deck in order to reduce the chance of ice dams.
It will put less stress on your attic floor does not require any additional fire retardant material it will not rot or decay it s eco friendly and will not support mold insects or.
In cold climates the primary purpose of attic or roof ventilation is to maintain a cold roof temperature to control ice dams created by melting snow and to vent moisture that moves from the conditioned space to the attic ventilation acts to bypass the vapour barrier created by most roof.
Also it will not lose its energy saving capabilities over time.
Throughout the balance of this digest the terms attic and roof will and can be used interchangeably.
Not venting the attic avoids this problem.
The table below shows what levels of insulation are cost effective for different climates and locations in the home.
Insulation level are specified by r value.
The higher the r value the more effective the insulation will be.
The higher the r value the better the thermal performance of the insulation.
Avoiding flash and batt condensation problems.
Step 2 measuring.
