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Heating · Our Favourite CombinationICF and Radiant Floor Heating:
ICF and Radiant Floor Heating:
Why the Two Belong Together
We have been building with radiant floors since the early 1990s and with ICF since 1995. Put them together and you get a house that is quiet, even, draft-free and cheap to heat. Here is why the combination works and how to design it properly.
The Short Answer
ICF walls cut the heat loss and keep the house airtight. Radiant floors deliver that smaller amount of heat gently, at low water temperatures, with no drafts and no ducts. In our own builds, ICF combined with radiant floor heating has cut heating costs by roughly 40 to 60% compared with a typical forced-air wood-frame house. The keys are a proper room-by-room heat loss, insulation under the slab, the right tube spacing and a boiler or heat pump sized to the real load, not to the old rule of thumb.
Why They Work Together
Small, steady load
ICF walls lose much less heat, so the floor only needs to run warm, not hot. Low water temperatures mean high efficiency from condensing boilers and heat pumps.
No drafts
Warm floors and warm walls. No blowing air, no cold spots under the windows, no dust pushed through ducts.
Thermal mass on both sides
Concrete slab plus concrete walls. The house holds its temperature through cold nights and power blips.
Quiet
No furnace roaring and no ducts carrying noise between rooms. Combine that with ICF walls and the house is genuinely quiet.
From our own builds
The 40 to 60% savings figure is what we see with ICF and radiant together, against a typical forced-air wood-frame house. ICF on its own, with ordinary forced air, is more like 25 to 40%. Your result depends on the house, the fuel and how you live in it.
Designing It Right
- Room-by-room heat loss. A CSA F280 calculation using the real ICF wall values. Our sister site OntarioHeatLoss.ca does these, including radiant design.
- Insulate under the slab. R-10 is a sensible minimum; more in a heated basement slab. Heating the ground is a waste of money.
- Tube spacing and loop length. Set by the heat loss of each room, not one spacing for the whole house.
- Zones. Separate zones for areas that behave differently: basement, main floor, sunrooms, garage.
- Controls. Outdoor reset so the water temperature follows the weather. Set it and leave it.
Planning ICF With Radiant?
This is what we build most. Send your plans and we will talk walls and floors together, so the heating is designed around the house you are actually building.
Boiler or Heat Pump?
Condensing gas or propane boiler: simple, reliable, efficient at low water temperatures. Air-to-water heat pump: increasingly popular, works best with the low temperatures an ICF house needs; plan for backup in the coldest weeks. Electric boiler: simple and cheap to install, more expensive to run, sometimes sensible for small loads like a garage or a shop.
What About Cooling and Fresh Air?
Radiant floors do not cool. An ICF house stays cool longer in summer, but most families still want some air conditioning. A small ducted heat pump or a couple of ductless heads usually does it. Fresh air comes from an HRV or ERV, which the 2024 OBC requires and which a tight ICF house needs.
What It Costs
In-floor radiant typically adds $12 to $20 per square foot of heated floor over a basic forced-air system once tubing, manifolds, boiler or heat pump and controls are counted, less if you also skip most of the ductwork. In a garage or shop slab, radiant adds roughly $8,000 to $15,000 for a two-car garage. See ICF garage costs for that version.
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
Is radiant floor heating good with ICF?+
It is one of the best combinations available. ICF cuts the heat loss, and radiant floors deliver the smaller load at low water temperatures with no drafts or ducts.
How much can ICF and radiant floors save?+
In our own builds, ICF combined with radiant floor heating has cut heating costs by roughly 40 to 60% against a typical forced-air wood-frame house. ICF alone with forced air is more like 25 to 40%.
Do I need insulation under a radiant slab?+
Yes. R-10 rigid foam is a sensible minimum and more is better in a heated basement. Without it, a large share of the heat goes into the ground.
Can a heat pump run radiant floors?+
Yes. Air-to-water and ground-source heat pumps work well with the low water temperatures an ICF house needs. Plan for backup heat in the coldest weather.
Does radiant floor heating provide air conditioning?+
No. Most ICF homes with radiant floors add a small ducted heat pump or ductless units for cooling.