|Autoclaved Aerated Concrete Projects
The benefits of using autoclaved
aerated concrete (AAC) are numerous. Perhaps in testament to
the versatility of AAC, the 3 residential projects described here
are quite different—but share a common theme of safety. A
large single family home in a forest, whose construction is being
managed by the owner himself; a modest single family home on a wooded
site, designed by an architect seeking environmentally sound and
healthy living; and a large development along the Louisiana Gulf
Coast requiring superior weather resistance.
Home, Maryland: Simplicity and Safety
Set in a southern Maryland forest, this large residence (6800 sq
ft) posed several construction challenges. So the owner, who is
managing the construction himself, wanted a simple system. That
turned out to be 12-in. AAC blocks. He needed their thermal insulating
and noncombustible properties to stand up to the home’s forest
setting, which included cold temperatures and, potentially, fire
hazards. The simplicity of AAC, he says, allows him, in one step,
to construct a structural wall that is insulated, resistant to termites,
and ready for finishing. He didn’t want to attach a siding
product, preferring instead direct-applied finishes: gypsum plaster
for the interior and stucco for the exterior.
Home: Healthy and Serene
More than 9 years ago, when architect Alice Dodson selected AAC
to build her own home, it was partly for health and environmental
reasons. A long-time sustainability advocate, she was also already
following Bau-biologie. Relatively unknown in the U.S., but well
established in Europe among architects and health professionals,
Bau-biologie is building biology or building for life. It resulted
after rapid construction in post-war Germany led to what we now
think of as sick building syndrome. So then, as now, she sought
healthy building solutions. To that end, she selected AAC blocks
and panels to achieve breathable masonry walls that emit no VOCs.
This creates an eco-friendly building, with a calming, quiet interior.
And with her firefighter husband involved in the building process,
having a noncombustible material was essential.
The AAC envelope also provides good thermal mass and insulation.
Thanks to an energy efficient envelope complemented by solar panels
and a wood stove, gas bills during the first year were only $100
for the 4000-sq ft home. The home can stay warm for 2 to 3 days
even after a disruption in power. Dodson likes how the material
can be sculpted with woodworking tools into various shapes and elements,
like columns and fireplaces, and continues to be a proponent of
AAC with clients, who appreciate its versatility and aesthetical
Grove at Inlet Beach: Safety and Weather Resistance
This success story occurred as a result of destruction caused by
Hurricane Katrina. As the Florida Panhandle’s first all-AAC
high-density residential development, The Grove at Inlet Beach is
intended to withstand future weather and safety challenges in its
Gulf Coast environment. All walls, floors, and ceilings of these
single family residences are made with AAC panels and blocks. The
excellent fire rating (4 hr for 4 in.) was key to local zoning approval,
and there are no structural fire concerns as a result. When hurricanes
arrive, these structures are prepared to meet 150 mph winds (Category
4), and with proper reinforcement, can be engineered to withstand
winds of 200 mph or more (Category 5). AAC homes are not destroyed
by floods, either: they resist rising waters, rot, mold, and mildew
and can be cleaned, repainted, and reopened to residents—no
As if the security and weather resistance weren’t enough reason
to select AAC for his own home, the developer anticipates saving
35% on his utility bills and 65% on his insurance premiums.
The “Suite” Comfort of Concrete
guests in a Georgia hotel are sleeping better tonight thanks to
autoclaved aerated concrete (AAC). About an hour outside of Atlanta,
the site for the Forsyth, Georgia Comfort Suites, a slim lot adjacent
to an interstate, posed a few challenges. And high land costs are
making it increasingly common to build on sites that have inherent
challenges such as noise, unlevel terrain, or minimal set-backs.
So developers turned to a concrete system to help meet their needs
for delivering a quality project—in this case, a strong, quiet,
4-story structure near a heavily traveled highway.
The all-concrete building, including a stucco exterior, incorporates
roofs, floors, and interior and exterior walls made from AAC panels
and blocks. AAC is a lightweight, cement-based material that has
been popular in Europe for more than 60 years. Its success in the
U.S. over the past few decades has been more limited, but material
producers once again see opportunity for growing the market with
today’s focus on sustainable development. The product is energy
efficient and can contain recycled material, both of which are appealing
from a green perspective.
Designers like AAC for a number of reasons: it is strong and dimensionally
stable, reduces sound transmission, insulates against temperature
changes, and stands up to fire, high winds, and moisture. Builders
favor its ease of construction, which includes the ability to be
sawed, drilled, and worked with hand tools, and that it only requires
thin joints (1/8 in.) to bond the system together.
In spite of all these excellent benefits , using AAC in today’s
economy would have been harder to justify if the bottom line didn’t
make sense. But the CEO of the hotel’s builder-developer-owner
noted that initial costs of AAC were close to other more traditional
products, and its operating costs provided savings for energy (12%)
and insurance (7%). AAC saves heating and cooling costs because
it is thermally efficient, and saves insurance costs (through reduced
premiums) in recognition that this is a safe property, both in terms
of fire and high wind resistance, protecting against damage in winds
up to 150 mph.
The builder credits a knowledgeable architect as key to working
with AAC. And when investing for the long term, he recommends choosing
AAC. The value–blocking out unwanted noise, withstanding high
winds, resisting fire, and saving operating costs—helps everyone
sleep better at night.
|Placing AAC floor panels
||Setting an AAC floor panel with tongue and