You will need to hot knife channels for the electrical and plumbing which takes more time then just drilling holes in the 2x studs...not a huge amount of time mind you, but a consideration.

Since other people do it this way I can understand why you say this. However, in my case I'm running electrical conduit inside the concrete walls and installing boxes as I lay the blocks. I'll pull the wire later.

For plumbing, some will be under the slab, and most of the rest will be in the interior walls and above the drop ceiling. For situations where I need plumbing in an outside wall, such as my shower, I'll build a 2x wall as you suggested.

I have considered all these issues and designed the house to eliminate as many of them as possible, thus minimizing the extra labor involved.

I would think placing horizontal and vertical conduit inside the ICF concrete core section would be way more work than just cutting channels on the interior EPS insulation side. The conduit would also hinder the flow of concrete during the pour and possibly create voids. Yes, we always place the PEX plumbing above the ceiling and in the interior walls to the extent possible. You still need to have penetrations for exterior hose bibs and electrical outlets. And don’t forget the penetrations required for electrical/water/sewer entry, dryer, HVAC, and stove hood.

I would think placing horizontal and vertical conduit inside the ICF concrete core section would be way more work than just cutting channels on the interior EPS insulation side.

It might be, but I already have the conduit, and I would rather not cut the EPS if I can avoid it. Besides, with conduit in the walls the wiring is better protected, and I can pull more wire later if I choose to -- without any remodeling or repair work.

The conduit would also hinder the flow of concrete during the pour and possibly create voids.

This won't be an issue if the concrete subcontractor understands the situation and knows how to deal with it. A vibrator and the proper slump can eliminate practically all voids, especially when lifts are only 3-4 feet each.

You still need to have penetrations for exterior hose bibs and electrical outlets.

My hose bibs will not be connected to plumbing inside the house (a zoning requirement based on my desire to have two separate sources of water on the property). Instead the hose bibs will be connected to vertical pipes that T-up from a one-inch water pipe that's buried around the perimeter.

And don’t forget the penetrations required for electrical/water/sewer entry, dryer, HVAC, and stove hood.

I may be old but I'm not so brain-dead that I will forget these things -- not yet anyways!

Electric, gas, water and sewer come in from beneath the slab. The washer and dryer will be located on the covered porch outside the back door so their supplies will come from beneath the porch floor. I will bury 6" galvanized steel ducting beneath the porch floor for the dryer vent.

Yes, there will be penetrations for the stove hood and mini-split, but I think that's all.

All good points and it sounds like you have thought it all through. We put the conduit in the interior EPS insulation...and place other provisional conduit there too. My concern with the conduit in the concrete core section is getting the pencil vibrator past the conduit and not having it hang up such that it can’t get to where it needs to go. Sort of the same reason why the window bucks are open on the bottom so you can vibrate under the windows and properly consolidate the concrete. You can’t go too wet with the concrete either or the hydro pressure will cause blowouts for sure. Maybe penetrations for inlet/outlet of ERV/HRV too?

1: The supposition that blowouts are the concrete guy's problem. No. Because, in the end it always comes back to being YOUR problem.

In short, take the time and care to make sure you have the blocks properly adhered together. And make sure you use blocking to reinforce areas where blowouts might be likely.

Belt AND suspenders.

2: You're down in termite country too. See if you can snag blocks that're termite resistant. At least for anything below ground and for 2 feet or so above. Also, look into termi-mesh on any slab penetrations (though you're probably already familiar).


3: Focus on your waterproofing. Yeah, the concrete is generally going to shrug off flooding. But any nasties carried into the wall assemblies can cause problems and leave you with a house that's uninhabitable. Take a look some of the latest at the Matt Risinger channel on YouTube. Ignore the host's Dopey Bro schtick. He's delivering good info on various methods of waterproofing homes. Will vary slightly as he's building out in Austin, TX. Warning. He is a "fine home builder" (builds giant E-Peen Mansions and charges crazy markup). But his basic build ethic is fairly good.

4: Even installing the conduit integral to the wall, you're still going to have to cut the EPS for the boxes. But you can use small squares of plywood to prevent blowouts. Seal the box. Screw the plywood to the box. Affix the box to the conduit. Screw the plywood into the screw/nailing strips in the ICF. Once the wall dries in, pop the plywood off and break the seal on the box. Make sure to take special care tie-wiring the conduit inside the wall. Don't let it just free-float on you could get it pushed out on a wall surface.

Dana may come along and make some suggestions about your insulation for dew point control. He's talking WAY above my pay grad, so I won't presume to speak for him.

It sounds like you're reasonably on top of things.

Oh, one more thing comes to mind before I call it a day... Having the conduit sticking up from the ICF concrete is going to make more work fitting the gasket and sill plate. It is bad enough that you have to drill holes in the right place for the cast in place concrete anchors (unless you go the drill and epoxy route), but having to deal with conduit too would be another hassle that is avoided by placing the conduit in the EPS after the wall is poured and the sill plate is bolted down. Anyhow, whatever rocks your boat...

Thanks for all the suggestions, it's great to hear them ... and I am definitely considering the possibility of using some of them rather than my original plans.