When it comes to building insula- tion, the options can be over- whelming. Luckily, the vast number of insulation types means that there are
plenty of alternatives out there, from natural
materials to recycled options.
Cellulose makes up the cell walls and
fibers in plants. Cellulose fiber insulation is
also the oldest form of insulation, and can
be added to enclosed walls and unfinished
attic floors as loose-fill, dense-packed or
Inexpensive and containing the highest
amount of recycled material of any commercial insulation, the cons of cellulose fiber
include the fact that it settles up to 20 percent, which can cause gaps, must be kept
dry and is heavier than fiberglass. However,
for a majority of building projects, these
conditions aren’t problematic.
Unlike malleable insulation types, cork is
a semi-rigid material usually made of 100
percent cork. Made of the outer bark of oak
trees that have reached a minimum age of
18 years, cork is a completely natural and
renewable resource, as removing the bark
doesn’t harm the tree and regenerates over
time. Harvesting can occur every nine years
throughout the tree’s approximately 200-
Using the same geothermal properties as
double-glazed windows, the air which fills
the space between the cork’s cells makes it
an excellent insulator — typically an R-value
of 3-4 per inch depending on thickness.
A form of cellulose fiber (cotton), denim
insulation contains the same advantages
of recycled paper. Made of the scraps and
clippings from denim manufacturing facilities, recycled denim insulation can be used
in place of fiberglass or mineral wool batts
between open roof rafters, ceiling joists and
This eco-friendly insulation has higher-than-average — about 30 percent higher —
acoustic ratings compared to other materials,
decreasing sound transmission and increasing sound absorption qualities, while also
providing a high rate of thermal performance,
between R- 13 and R- 30.
Fiberglass is well-known in the building
industry for its durability and lightweight
properties. Made up of thin fibers of glass,
it traps pockets of air, keeping spaces
thermally regulated and insulating against
sound transmission between floors or walls.
According to some estimates, fiberglass can
reduce energy costs by up to 40 percent.
However, because the material is made up
of very fine slivers of glass, beware of several hazards of using fiberglass insulation,
including particles coming into contact with
skin and airborne particles being inhaled. It’s
suggested that the insulation be dampened
before attempting to remove old batting.
Offering superior fire resistance and
acoustical performance, mineral wool insulation doesn’t contain organic compounds
such as wool.
It’s created by spinning or drawing molten
mineral, glass, industrial slag and rock until it
becomes fibrous materials.
Suitable for both wood- and steel-framed
buildings, mineral wool is typically made of
more than 90 percent mineral fibers and
bonded together with binders such as phe-
nolic formaldehyde, which can be problem-
atic to those wishing to decrease their use
of formaldehyde and VOCs.
Similar to cork, mycelium insulation is
a natural material — fungus — bonded
together and providing an R-value of about
3 per inch.
The rigid blocks are made by intertwining the rootlike filaments of a fungus in
controlled conditions. The material has only
been used for a short time, but new uses are
being invented constantly.
Unlike polystyrene insulation, mycelium
insulation can withstand heat without additives. Along with the fact that it’s relatively
low-cost to create, manufacturers of mycelium, including Ecovative Design, see it fitting
into a number of building projects.
The catch? It’s promising, but not quite
ready to be used as insulation.
With wool insulation, the natural, renewable resource is not only VOC-free, but the
amino acids in the wool can irreversibly bond
with formaldehyde and other pollutants to
filter air and improve the indoor air quality.
Installed like other malleable materials
without the need for protection, wool batts
are rated at R- 3. 6 per inch and loose-fill performs at R- 4. 3 per inch.
Both batt and blow-in wool insulation
provides sound absorption and transmission.
While it doesn’t support mold growth
and minimizes condensation, maintaining
R-value when wet, wool does absorb and
release moisture from ambient air, so the
location of the building should be discussed
when purchasing wool insulation.
Kadie Yale ( firstname.lastname@example.org)
is architecture and design expert for
Green Ways to Insulate Your Building
LOOKING AT SEVEN DIFFERENT TYPES OF INSULATION TO CONSIDER
FOR YOUR NEXT PROJECT
FIBERGLASS is fire-resistant, low-weight
and malleable. The spongy material has
been used for decades.
WOOL is a natural and renewable resource
that is VOC-free. It provides sound
absorption and transmission.