Building the AAC Walls

To build the walls of the house we used AAC blocks, or Autoclaved Aerated Concrete.  They are made out of a mixture of sand, lime, cement and water.  Aluminum powder is added for a chemical reaction that gives the block its properties.  AAC is highly thermally lightweight, and easy to install, provied structure, insulation, and fire- and mold-resistance.  In addition, the material is workable and forgiving.  Although it is derived from natural elements, it is not naturally existing because it involves processing.  However, the benefits of using the material balance out the production.  It has a lower environmental impact than standard materials (drywall, etc) because of its improved thermal efficiency reduces the heating and cooling load in buildings.  AAC block walls do not need seperate insulation and many layers like used in conventional building of walls, because it is all in one.  However, there needs to be an exterior and interior coat of plaster to protect it from the elements.

mortar bed and leveling

mortar bed and leveling

thinset

thinset

To make sure that the bond beam was completely level, we mixed mortar in a 3:1 ratio of sand and mason’s cement.  This gave us enough of a bed to lay the blocks and adjust the level on all sides if necessary.  After the first course, there is no need for a thick bed of mortar, instead thinset was applied using a notch trowel.  Before continuing with the rest of the courses, blocks needed to be cored for the corners and the sides of large windows and doors.  This is for structural support.  Once the walls are built with cores in necessary places, the holes will have a long piece of rebar and filled with concrete.  The side cores will have rebar with thread welded on the top that will bolt down the top plate.  The method we used was building up the corners so that we could set a string for plumb and core/cut as we go.  Lintels, long pieces of AAC with rebar inside are placed over window and door openings.

building up

building up

structural column

structural column

block finished on main house

block finished on main house

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