Poured Foundation

It’s been a few weeks, and we’ve made quite a lot of progress on the house. We had evaluated a number of manufacturers, but ultimately decided upon Nudura for our ICF foundation. Paul Stevens and his crew from Stevens Construction handled the formation and pour of the foundation, and by all accounts they did a smashing job.

The Nudura product comes shipped in a collapsed state, which I believe reduces shipping costs and makes it easier to handle by the workers. The ‘blocks’ look to be about 7’-8’ long, and they basically just snap together. For the odd sizes, the blocks are simply cut with a handsaw. A crew of 3 guys assembled the wall, and the process looked to be pretty straightforward:

1. First, the footings are formed and poured. The footings are basically a short concrete wall that the ICF blocks will sit on, and their main purpose is to displace the weight of the structure above.
2. Once the footings have cured, the forms are removed and 2 metal strips are attached. The strips were used to keep the bottom row of the ICF blocks straight and true.
3. The ICF blocks were then assembled and wood planks are added (in certain areas) for additional support. Permanent wood forms are also built to create the window wells.
4. The blocks themselves have a “mesh web” built into them, but additional horizontally and vertically rebar is also placed inside.
5. Large metal braces are temporarily installed to support the wall during the pour. These braces acted as a walkway for the crew during the pour, plus they were also used to fine tune the straightness of the walls once the concrete is poured.

1. Additional wood bracing was also added throughout to ensure the structure is maintained during the pour.

   This isn’t exactly on par with the demolition video, but here’s a little video that illustrates how the foundation walls came together.

   Once everything was formed, supported and ready for concrete, I made a point of calling our architect and setting up an inspection before the pour. Nothing too major was out of place, but there were a few things that needed to be adjusted to ensure we maintained the aesthetic we were trying to achieve (one wall was jutting out about 6 inches further than it should have and would have resulted in an unsightly ‘hump’ in front of the stairs). We also decided to abandon the window in the study under the garage. I had raised concerns about this earlier on in the design process, but we made the decision on-side because it quickly became clear that the window well would have been too large for the space along the house. Once these oversights were corrected, it was time for concrete.

   A relatively liquid concrete was poured into the hollows of the ICF walls, which allowed it to easily slide through the webbing and rebar. The crew would walk around the walls and fill it up a few feet, and then continue around to fill it another few feet. Every so often they’d stop and use a large vibrator to ensure all air bubbles were worked out, and the concrete made its way into every crevasse. I definitely have to give some credit to Paul and his team – lugging around the pumping house didn’t look like much fun.

   The walls stayed untouched for a few days to allow the concrete to cure, after which the the weeping tile, crushed gravel, sand, and backfill were added. Sand was used because it allows for better drainage, and the weeping tile is basically a plastic, sock-covered tube that wraps around the perimeter of the house. It’s sole purpose is to capture any water that seeps into the ground, and move it away from your foundation. In our case, we have a “soak away” pit in the backyard which will capture most of the rainwater runoff and allow it to dissipate naturally into the ground.

   I’m definitely glad we’ve moved past this phase, as there were a few hiccups we encountered along the way which increased the foundation budget by about $2000. In particular, we had a little turbulence between the trades and the structural engineer, but I’ll explain this in another post soon.

   Post Tags: concrete, foundation, ICF, Nudura, Wall

   Posted by Jeremy Bell in: Construction + Eco / Green

    
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