Concrete is then poured into the space and allowed to set.Jewson is a brick supplier to trade and self-build customers, giving you access to the house bricks, cement and other building materials you need. After the blocks are stacked, rebar is placed in the hollow gap between the foam panels. Consisting of two sheets of high performance insulation held together with a proprietary tie system, ICF blocks are lightweight foam blocks that can be stacked on site to build almost any type of building. Insulated concrete forms (ICF) are a good alternative to traditional and autoclaved aerated concrete block construction. Insulated Concrete Forms: A Better Alternative Autoclaved aerated concrete blocks must be protected from aggressive environments and are typically not a good candidate for below grade construction. Water absorption also weakens the strength of the wall, even if cracking does not occur. If water trapped in these pores freezes and expands, cracking can occur which will damage the structure. Water can be retained inside these pores so any finishes applied to the wall must be able to breathe. The aeration process creates millions of tiny holes or pores inside the concrete block. One of the biggest disadvantages of autoclaved aerated concrete blocks is the ability of the block to stand up to water over time. With transportation costs increasing, the cost of building with these blocks goes up too. While lightweight, the blocks must also be transported from the manufacturing site to the construction site. AAC blocks also typically have half the compressive strength of traditional concrete blocks so it is critical that the blocks are used in the correct applications.ĭue to the aerating agents used, autoclaved aerated concrete blocks are more expensive than traditional concrete blocks. Proper mortar techniques must be used to ensure the blocks are combined together to form a stable structure. Installers must be knowledgeable on working with these panels to ensure that installation is done correctly. The Disadvantages of Autoclaved Aerated ConcreteĪutoclaved aerated concrete blocks have some attractive advantages, they also have three big disadvantages that should be considered before using them in a building project.Įven with more than 80% of the panel being air, large autoclaved aerated concrete panels can be quite heavy and require a crane for installation. Many autoclaved aerated concrete buildings are eligible for LEED credits. This thermal mass helps to slow down the effects of temperature swings outside from affecting the change of indoor temperatures, which reduces energy usage. The R-values of these blocks are comparable to conventional frame walls but have the added benefit of thermal mass. The tight dimensional stability of AAC blocks also allows for a tighter building envelope, to keep air from leaking in or out of the building. Fire resistance of these blocks is also excellent with many eight-inch thick blocks capable of a four-hour or longer fire rating. Screws and nails can be used in these blocks easily, as well.Ĭoncrete naturally resists water, insects, mold, and mildew giving it an advantage over other traditional building materials. The lightweight properties of these blocks also make them easy to cut and shape as needed. The heat and pressure that the AAC blocks are exposed to during construction gives them a great deal of inherent strength. These advantages are important to weigh against costs and downsides but make this type of concrete an important option for any new construction.Īutoclaved aerated concrete combines a wall’s structural elements and insulation into one easy-to-construct material. The Advantages of Autoclaved Aerated ConcreteĪutoclaved aerated concrete (AAC) blocks bring many unique advantages to buildings including durability, energy efficiency, and safety. After the concrete sets, the blocks are molded into perfectly dimensioned units for use on construction sites. The autoclave applies heat and pressure to the blocks for at least 12 hours to strengthen the block for use in construction.Ī finished autoclaved aerated block contains more than 80% air. Once the blocks are shaped, the forms are removed and the block is sliced before being placed in an autoclave. The expansion agent causes the “mix” to expand and rise just like baking bread in the oven. Made from fine aggregates, cement, and an expansion agent, autoclaved aerated concrete blocks are lightweight versions of concrete blocks. What Are Autoclaved Aerated Concrete Blocks?