There is more to attic insulation
than just picking the cheapest material
to achieve a given R-value. Almost
every common attic insulation has
some peculiarity that must be considered.
Also we are still learning new
things about insulation performance
in different climates.
This column is an update of
important attic insulation issues
that are commonly overlooked or
Heat Doesn't Rise
The most common misconception
about attic insulation is that attics
need higher R-value than walls
because heat rises. This is not true.
Heat does not rise; it travels
equally in all directions — up,
down, and sideways. Warm air does
tend to rise. However in rooms with
high solar gain, the air temperature
near the ceiling of a well-insulated
house is typically