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Plumbing an ICF House: Sleeves Before the Pour, Drains and Radiant Tubing Before the Slab, the Sump Pit, and a Basement Bathroom Roughed In for Later
Plumbing & Water
Plumbing an ICF House: Everything That Goes Through Concrete Gets Decided Before the Concrete
The plumbing inside an ICF house is ordinary plumbing. The interior walls are wood frame and the plumber runs them the way he runs any house. The difference is the outside walls and the basement floor. The walls are concrete inside foam, the slab is concrete with radiant tubing in it, and both get poured once. Every pipe that has to pass through either one has to be there first. This page is the list and the order.
Two Pours, Two Deadlines
An ICF exterior wall is two layers of foam held apart by webs, filled with concrete. Once it is poured you have a reinforced concrete wall, which is the point, and it does not care that you forgot the hose bib. If you have never seen the forms, the what are ICFs page shows them, and ICFPro.ca covers the walls and foundations from the contractor’s side.
The basement slab is the second deadline. In our houses the hydronic radiant tubing is tied down before the slab is poured, so the drains under the floor, the sump pit and any bathroom you might finish later all have to be placed, inspected and protected before the tubing goes down on top of them. After the pour, a forgotten drain is a jackhammer, and a jackhammer in a heated slab is a jackhammer near the heating pipes.
So there are two moments in an ICF build where the plumber has to be finished thinking: before the wall pour and before the slab pour. Neither one waits for anybody.
The Penetration List: Every Pipe Through the Wall
A frame wall forgives you. The plumber drills a hole through the rim joist in five minutes. A poured wall does not. Forget a sleeve and it is a core drill: an allowance of $150 to $400 a hole, plus the patch and the seal so it does not leak, plus the trip.
Before every pour we walk the house with the trades with a list of every penetration. For the plumber that list looks like this:
- The water service from the street, or the well line from the pitless adapter, coming in below frost.
- The building sewer going out to the street, or the line to the septic tank.
- Every hose bib: front, back, garage side, and the one by the garden you have not planted yet.
- The dryer vent.
- The boiler or water heater vent, if the appliance vents through the wall. Where that is a gas appliance, the gas contractor decides the vent; ask them before the pour, not after.
- The sump discharge line, and the radon pipe if it leaves through the wall.
- A spare sleeve or two where a future outdoor shower, hot tub or pool line might go.
Say the list comes to 10 plumbing sleeves and two get missed. At $275, the middle of our allowance, that is 2 x $275 = $550 in core drilling, before anybody paints the patch. A spare sleeve costs a piece of pipe. Capping one you never use is cheaper than renting the drill.
Rule of thumb: if water goes through it, air goes out through it, or a pipe might ever need to reach the outside through it, it gets a sleeve before the pour.
What It Costs
An ICF house is plumbed and priced like any other new house, by the fixture, and the new house plumbing cost page has those numbers. No plumber we found publishes an ICF premium, so we do not show one. What changes the bill is getting the order wrong.
| Item | When | Cost |
|---|---|---|
| Rough-in per fixture, new construction | before insulation | $800 to $1,200 |
| Setting the fixture (trim) | finish | $250 to $350 |
| Sleeve set in the form | before the wall pour | a piece of pipe and a few minutes |
| Core drill through a poured wall, patch and seal | after the pour | $150 to $400 a hole, allowance |
| Basement 3-piece roughed in later, stubs in place | years later | about $4,500 |
| Breaking the slab to add drains | years later | adds $1,500 to $8,000 |
| Sewage ejector, if the drains sit below the sewer | either | adds $1,500 to $3,500 |
October 2026, before HST, from published Ontario plumber and renovation contractor pages. The slab figures are for an ordinary slab; nobody publishes a price for cutting a slab with radiant tubing in it, and a careful plumber will want the tubing layout first.
Why Ontario prices are all over the map: the plumbers and guides we checked quoted very different prices for a basement bathroom rough-in, which is the one an ICF slab decides for you. A GTA renovation contractor said $3,000 to $6,000 for a 3-piece. A Toronto plumber said $3,500 to $14,000. A renovation cost guide said $4,000 to $8,000 for a half-bath. The gap is whether drain stubs are already in the slab, whether the floor gets broken, and whether an ejector is needed. Budget $4,500 with stubs in place, and get two or three quotes on the same written scope.
Rough In the Basement Bathroom Now
If there is any chance of a bathroom in the basement, the drain stubs and vent go in with the underground, before the radiant tubing and the slab. In a new house that is three more fixtures on the rough-in, about 3 x $1,000 = $3,000 at our default, capped and buried in the right spots.
Do it later instead and the same 3-piece is about $4,500 with stubs in place, plus about $4,000 at our default to break and patch the slab if they are not there: $8,500, and now somebody is cutting a heated floor. That is $5,500 more than the $3,000, for a bathroom you might have finished anyway. The bathroom rough-in cost page has the later cases worked out.
The sump pit goes in at the same stage. A sump that takes weeping tile water needs a water- and air-tight cover under Article 7.4.6.3 of the Code, and its discharge goes outside through its own sleeve, never into the sanitary sewer, a floor drain or a laundry tub. The weeping tile and sump page covers the drainage side.
Who Does What, and What the Inspector Sees
I am a builder, not a plumber. On our ICF builds the plumbing is done by licensed plumbers we hire. My job is the order: the plumber marks sleeves before the wall pour, finishes the underground before the slab, and the inspector sees it before anybody covers it.
- Groundwork inspection before the slab. Municipal guidance puts the under-slab plumbing inspection before backfill and before the concrete floor is poured. Book it about 2 business days ahead, and do not let the radiant crew tie tubing over pipe nobody has inspected.
- Water service and sewer before backfill. The inspector sees them in the trench where they come through the wall.
- Rough-in before the walls close. The drain, waste and vent piping is water-tested to the roof line before walls and ceilings are covered.
- Supply pipes stay out of the exterior walls where you can manage it. That is the usual rule in any Ontario house. ICF walls are warm, but a plumber who runs the supply in the interior walls will never have to cut foam to fix a leak.
Plumbing in a house this tight pays you back. Our ICFhome.ca showhome in Tiny Township is ICF with radiant floors and costs about $100 a month to heat in the coldest part of winter, and every pipe through its walls was planned before the concrete truck showed up.
Questions people ask
Can you run plumbing in ICF walls?
You can, but the usual rule in any Ontario house is to keep supply pipes out of exterior walls where you can. In an ICF house the interior walls are ordinary frame and carry most of the plumbing. The exterior walls mostly see sleeves passing straight through.
What has to be sleeved before an ICF pour?
The water service or well line, the sewer or septic outlet, hose bibs, the dryer vent, any boiler or water heater vent through the wall, the sump discharge, the radon pipe if it exits through the wall, plus a spare or two.
What does it cost to drill through an ICF wall later?
We carry an allowance of $150 to $400 a hole for a core drill with the patch and seal. Nobody publishes an Ontario price for it; it depends on the wall thickness, the rebar and how far the driller drives.
Should I rough in a basement bathroom in a new house?
If there is any chance you will want one, yes. About $3,000 at our default in the new build against about $8,500 later if the slab has to be broken, and more if the slab has radiant tubing in it.
Is plumbing an ICF house more expensive?
No plumber we found publishes a premium. The fixtures are priced like any new house. The money goes on forgotten sleeves and drains missed before the slab.
Price the plumbing, then check the list
The plumbing cost estimator prices an ICF house the same as any other, with a basement or slab and town water or a well. If you have a plumbing quote for an ICF build, the $99 review reads it, up to three quotes, and tells you whether the underground, the sleeves and the rough-in for later are in it.
Sources and further reading
- ICFhome.ca: where I build the ICF houses with radiant floors these plumbing notes come from.
- ICFPro.ca: ICF walls and foundations, including the sleeves and penetrations planned before the pour.
- The 2024 Ontario Building Code: Ontario on the 2024 Code: in force January 1, 2025, the grace period to March 31, 2025, and the harmonization with the national codes.
