Wall
insulation | Drywall
| Finish carpentry
| Paint | >>Attic
and crawlspace insulation | Hard
floor coverings
After the ceiling drywall is in place, the attic insulation
can be installed. The crawlspace insulation is installed
after the electrical, plumbing and HVAC are inspected,
often called the 4-way inspection. 
Attic insulation is typically blown into the attic
space with an insulation blower. Most insulation installers
have a truck mounted blower. The insulation is fed
into a hopper in the truck and blown into the attic
via a 4" hose. Fiberglass and cellulose are probably
the most popular insulation materials. Cellulose and
fiberglass equal approximately 3 R value per inch
of material. If an attic R-value of 36 is required,
you would install the insulation to a depth of approximately
12". Most insulations contain fire retardant
to inhibit combustion.
Insulation batts can
be used in the attic space. However they are more
labor intensive than blown in insulation. Blown in
insulation is also able to fill in cracks and gaps
that batts can't.
Care must be taken when installing attic insulation.
The worker must walk on the ceiling rafters. The drywall
will not support his weight and will be damaged if
stepped on.
The attic space needs to be well vented. Otherwise
in winter moisture has no way to escape. As warm air
rises past the ceiling and insulation, it meets with
cool air and causes condensation. The moisture condenses
on the underside of the roof decking and drips back
into the insulation. This leads to mold and mildew
and rotting in the attic space.
Click on the image below
to view enlarged attic diagram
In the summer attics get very hot, sometimes over
140°. If heat isn't allowed to escape the effectiveness
of the insulation is reduced, and the life expectancy
of the roof components is reduced. Attic fans are
an effective method of cooling attic spaces.
Roof, eaves and gable vents are installed to alleviate
this problem. It is important that the eaves vents
have baffles properly installed so that insulation
blown-in insulation doesn't block the air flow from
the eaves vents to the roof and gable vents. Insulation
installers are responsible to install these baffles
before blowing in insulation.
Attic insulation is not a critical path task. There
is ample room in the schedule to complete it. It usually
takes less than a day to complete an average attic
space. However it is recommended that it is installed
as soon as possible after the Drywall lid (ceiling)
is complete thus saving on heating and energy cost
and making the work space more comfortable for subcontractors.
Insulation is priced by the square foot of and R value
of the material. An insulation blower can be rented
from rental centers and some home centers. Installing
attic insulation is not a highly skilled trade, however,
care must be taken when walking through the attic
space.
