Residential 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.

Handal 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.

Dodson 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 potential.

The 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 rebuilding necessary.

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.

Low-Rise Buildings

The “Suite” Comfort of Concrete

Some 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 groove joint

 
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