Last week workers set the insulated concrete forms (ICF’s) for the foundation walls on the new house we are building. This system uses blocks make of expanded polystyrene insulation with the walls connected with plastic reinforcing. The white blocks go together like giant Lego building blocks. Foam adhesive is used to bond the blocks together. As the blocks are put in place we install lengths of reinforcing steel. Once the blocks are all set they are straightened and held in position with braces. We install small sloped shelves on the walls where concrete slabs will meet the foundation. These support the concrete slab and make sure the concrete slab will not settle.
We have one area where a window is needed in the wall. Here we form out the opening using framing lumber. The area over the window gets extra reinforcing steel. The framing lumber stays in position and creates a rough opening for the window itself.
After the ICF’s are set and straightened, we then pump concrete into the cores of the insulated forms. We do this using a large truck mounted concrete pump. The concrete trucks back up to the pump and discharge their concrete into the hopper. The pump then pumps the concrete up into a boom mounted hose and the workers guide it into the ICF’s. This takes careful work. The consistency of the concrete is critical and the flow rate from the pump truck is critical. If either of these is wrong, the ICF’s can ‘blow out’ from the pressure of the concrete. In this case everything went just fine. The workers went around the foundation several times adding the right amount of concrete each time. The result is a very strong reinforced concrete foundation wall that is very energy tight.
For the rest of this week we will let the foundation walls cure. We don’t want to risk pushing over a wall by placing soils against it when it is still ‘green’. When we do start to backfill the foundation we will install special braces to help support the wall. Once the wood floor system is in place the tops of the wall are permanently tied together.
It was another beautiful day today and we made use of it by installing the walk-out draintile and connecting the draintile to the footing Form-A-Drains. We use perforated draintile that has a filter ‘sock’ on it. The filter keeps out silt so the draintile will work for many, many years. The draintile is joined using tees, elbows and splicers. This drainage system will all drain out the rear of the house to daylight by way of a solid sewer pipe.
We also started work on the private on-site sewer system. The 1500 gallon concrete septic tank was delivered and lowered into the prepared hole. It was good to have dry weather to navigate this tank into the hole with the truck crane.