Basement ICF Poured

Yesterday afternoon saw the pour of the basement ICF walls.  At this point of the build these pours are the piece I'm most nervous of - I've seen an ICF build that had a noticeable wave in the wall due to movement of the ICF blocks during the pour (and failure to correct after).  This has knock on problems later with internal and external plaster costs increasing.

There was only about 13m3 of concrete to go in and with the use of a concrete pump this is a quick process.  With 2 cement trucks lined up to go we set up the pump on the top level of the cleared area, and the swing arm has plenty of reach left when we were pouring.

The pump itself is quite an impressive machine.  While pouring, the pump nozzle is constantly being moved around to keep the levels from building too far in a section of the wall.  After the first cement truck was empty the concrete was vibrated to remove some of the air trapped in the concrete.  The second load is added and concrete poured into the window cill openings.  The whole lot is floated off at the top and cills and the trucks head offsite, after an interesting display of "hide the sponge" while the pump is getting cleaned.

The next part is truing up the walls.  The jacks that are holding up the ICF are adjustable and there is a race against time to get the walls inline before the concrete hardens too much.  There is a builders line at the top of the wall that is used to check its horizontally aligned, and a level against each section to get it vertical.  After a number of adjustments things look good, and we leave the wall to cure.

Into the wall we've set a number of ducts - 400x200mm areas for dual HRV ducts, 4" pipe for electrical cables - both of these are set into the ceiling area.  For the vacuum there is a set of 55mm pipes in the subfloor area.  Hopefully these are all correctly set and we won't be breaking through the walls later.

So next week we're back on groundworks and a few other bits and pieces.  We need to tank and backfill against the retaining wall, install a drain at the back of the wall and raise up some of the level that the top section of the house will sit on.  Foundations for load-bearing walls on the ground floor also need to go in, floor slabs on top of the basement and for the ground floor and then we're ready to raise up again.

All going well, ideally we'll be looking to get the roofer onsite in about 4 weeks.