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Autoclaved Aerated Concrete (AAC)


What is Autoclaved Aerated Concrete (AAC)?

AAC is type of concrete material made from many different aggregates, such as a cement mixed with an expansion agent. Typically AAC will be made into blocks that are mostly air. These blocks start out being produced in a factory where the mixture will ride and harden similarly to bread dough.

These blocks are then used to create structures of all shapes and sizes. The blocks and sometimes panels are stacked and joined using some sort of motor, same with traditional brick. As you see in the picture above, the blocks will need to have some sort of finish, such as stucco, or traditional siding.

Due to the types of materials used in the process of manufacturing AAC, you will find that these blocks or panels provide excellent thermal insulation on top of being extremely fire resistant.

Physical properties of Autoclaved Aerated Concrete (AAC) (Can vary from manufacturers):

Density: 20 -50 pounds per cubic foot – AAC is actually light enough to float in water.

Compressive Strength: 300 to 900 psi

Shear Stress Allowance: 8 to 22 psi

Thermal Resistance: 0.5 to 1.5/inch of thickness

Sound Transmission: 45 for a typical 8 inch block


What are the Pros and Cons of AAC?


Composite material – AAC combines the structural component as well as the insulation for the walls, floors, and even roofs. Making this composite material a must, when wanting to build quickly and efficiently.

Flexibility during construction – Autoclaved Aerated Concrete (AAC), unlike traditional concrete, you are able to make adjustments to the shape of the material on the fly. Being able to shave or cut out portions of the walls for plumbing or electrical can ensure easy field adjustments. Due to its cellular properties and strength, AAC can take all types of nails and screws for added flexibility.

Overall Strength and Durability – AAC is an excellent material for overall durability and stability. Being a cement based material, AAC will resist, water, mold and mildew, as well as insects. The cement base also creates a structurally safe home when completed.

Fire Resistance – Autoclaved Aerated Concrete (AAC) is typically 8“ – 10” thick which can surpass far beyond a four hour fire rating. If you live in a wildfire danger zone, this is a must have material in current times.  AAC is also noncombustible, meaning if the structure does find itself in a fire, it will not burn or give off toxic fumes.

Typical Connections – Roof, wall, and floor connections are standard. Conventional top plates for roof, standard ledges for floor framing, or AAC floor systems can dear on top of AAC walls.

Cons or Limitations –

Low availability – AAC is not as available as most concrete materials. More manufacturers are popping up around the country however, and most are willing to ship.

Reinforcement – Lightweight it great and Autoclaved Aerated Concrete is strong however, it does require a good amount of reinforcement to be applicable in higher loadbearing situations.

Exterior Finish – AAC is a very porous material which will require an extra material for the finish. This is required for the health of the material as well as look and feel of the home.


PSE Consulting Engineers and Autoclaved Aerated Concrete (AAC)

As many of the other sustainable materials that we work, our professionals have the knowledge and experience to complete your structural analysis and design for the next home builder or manufacturer.

AAC along with all other fire resistant materials hold a special place in our company. PSE is located in Southern Oregon and we have watched our neighboring buildings and cities fall victim to forest fires in the last 5-10 years. We highly recommend this product to our clients in the local area as well as any other client impacted by fires.

Where do i start with PSE Consulting Engineers?

If you are wanting to start a project as a home owner, contractor, or manufacturer. Feel free to reach out to us via website, phone, or email us directly at We always offer a free initial consultation and would love to team up on your next project. PSE offers competitive pricing and great turnaround times.

PSE offers the following services for anyone looking to build a home:

  • Custom Home Design (Completely custom home design services at the most affordable prices. This service is a full architectural plan set with floorplans, elevations, and renderings of your new home.)
  • Structural Analysis and Design (Required for permitting, we carry P.E. stamps in all 50 US States and 4 Canadian Provinces)
  • Consulting – Our professionals at PSE are always on standby for additional consulting, or questions for any building type or material.