Planning Ducting

The HRV Installer called over to the site on Saturday morning, mostly to nose around and say hello (and get some money) and to see what we're about.  From my perspective it was good to discuss exactly how he wants us to prepare the walls for allowing his ducts to pass through.  With ICF, getting a hole in the wall after the fact is not easy - you need reasonably expensive drilling bits, and they get destroyed. So planning anything in advance saves a vast effort later.  The same for the central vacuum, and we'll also put in smaller ducts for routing electrical cables around during the 1st fix.

Rather than placing the ducts in first and pouring concrete around them we'll put in a frame that allows 25mm around the duct.  There are 2 good reasons to do this - 1) the ducts have an insulation jacket around them that might not play nice with the concrete and 2) it allows a little wiggle room for the installer to move the pipes and generally adjust the length etc with less cutting.  So after 10 mins of agreeing the installation followed by an hour talking about rugby another piece of the overall jigsaw has been specified.

Also we're trying to determine the best way to tank the retaining wall.  Initially we were not going to backfill to the wall with earth and just have the drain at the back of the wall.  But the tanking system was concerning me.  The system is to use a bitumen membrane that is waterproof and is stuck to the ICF wall.  This is also taped to the radon barrier to provide a watertight layer wrapping the house.  The membrane is reasonably delicate, so on top of that is hung what is effectively industrial bubble wrap.  Its the same system used across the road.  The problem is that without backfill, the only thing holding it up is sticky pads, and I didn't think they'd last 30+ years.    So - on going back to the supplier the only solution is to backfill the cavity to hold the membrane against the wall - or go with a spray on plastic coating at twice the price.  Backfilling is a messy job but worth it in the end.

Hopefully we'll get the walls poured this week - it seems slow going again but the formwork is largely completed (we now have a doorway) with the delay being detail on how the stairs will sit (we'll be casting the stairs in place with concrete) and need to plan where starter bars that protrude from the wall will have to go.  Its a tricky piece of detail and the architect needs to get his measurements right here.  But - by the end of the week we may finally have an enclosed structure on the site, and getting the next foundations sorted out.