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Trades GuideWiring and Plumbing in ICF Walls:
Wiring and Plumbing in ICF Walls:
Where the Boxes, Wires and Pipes Go
Electricians who have never seen ICF tend to stare at the wall for a while. It is easier than it looks. The wires live in the foam, the concrete stays solid, and anything that passes through the wall gets planned before the pour.
The Short Answer
In an ICF wall, cables run in channels cut into the foam with a hot knife or router, and electrical boxes fasten to the webs or use boxes made for ICF. Anything that goes through the wall, like dryer vents, hose bibs, service entrances and plumbing stacks, needs a sleeve set before the pour. Plumbing mostly stays in interior walls. The electrical inspector still checks depth, protection and box fastening, so your electrician should follow ESA requirements and the box manufacturer’s instructions.
Running Wires in the Foam
The electrician cuts a channel in the foam with a hot knife or a router, presses the cable in, and holds it with foam adhesive or clips. The channel should be deep enough that the drywall screws cannot reach the cable. Where a cable runs close to the surface, it gets a steel protection plate, the same idea as in a wood stud.
Keep horizontal runs to a minimum and plan them at a consistent height, so the drywall crew knows where not to screw. A photo of every wall before drywall is the cheapest insurance you will ever buy.
Electrical Boxes
- Boxes made for ICF screw to the webs and sit at the right depth for drywall.
- Standard boxes can be fastened to a web or to a wood block glued into the foam.
- Panels mount on a plywood backboard fastened to the concrete.
- Exterior lights and receptacles need a box or block placed before the siding goes on.
ESA
In Ontario the Electrical Safety Authority inspects the rough-in. Your electrician is responsible for meeting the Ontario Electrical Safety Code for cable protection and box support. If they have never done ICF, ask them to call their inspector before they start.
Anything That Goes Through the Wall
This is the part that bites people. Every hole through the concrete should be sleeved before the pour with a PVC or ABS pipe a size bigger than what will pass through it.
Electrical
Service entrance, generator inlet, heat pump line set, exterior outlets.
Mechanical
Dryer vent, HRV intake and exhaust, range hood, furnace intake and exhaust, gas line.
Plumbing
Hose bibs, water service, sewer or septic outlet, sump discharge.
Forgot one? It can be core-drilled afterwards, but that costs money, makes dust and needs care around the steel. Our pour day guide has a sleeve checklist.
Get a Real Number for Your Project
Send us your plans or a rough sketch. We price the ICF work from real wall areas, not guesses, and tell you straight if ICF is not the right fit.
Plumbing
Keep supply and drain lines in interior walls. Exterior walls in Ontario are a poor place for water pipes anyway. Where a pipe must run in an exterior wall, it sits in the foam on the warm side with the concrete behind it, and it gets the same protection plates as wiring.
Plan It Before the Pour
- Mark every penetration on the drawings: what it is, size, height and location.
- Walk the layout with the ICF crew, the electrician and the HVAC installer.
- Set sleeves and blocking as the walls go up.
- Check them all one last time before the pump truck arrives.
Get a Real Number for Your Project
Send us your plans or a rough sketch. We price the ICF work from real wall areas, not guesses, and tell you straight if ICF is not the right fit.
Questions We Get
How do electricians wire an ICF house?+
They cut channels in the foam with a hot knife or router, press the cable in, and fasten boxes to the plastic webs or use ICF boxes. Cables that run close to the surface get protection plates.
Can you run plumbing in ICF walls?+
You can, in the foam on the warm side, but it is better to keep plumbing in interior walls. Pipes that pass through the wall need sleeves set before the pour.
What happens if you forget a sleeve before the pour?+
The hole can be core-drilled afterwards, but it costs more, needs care around the rebar and may need the engineer to look at it near openings.
Is ICF wiring more expensive?+
Slightly, mostly in the electrician’s learning curve. Experienced electricians often say it is no slower than wood frame.