Radiant & Hydronic Heating Design for Ontario Homes — Built on Real Heat Loss Numbers
Radiant floor heating is the most comfortable heating system you can install — and the most unforgiving when designed by guesswork. We design your system using your certified CSA F280 room-by-room heat loss, so every loop, every manifold, and every supply temperature is calculated for your specific home and Ontario's coldest days. For ICF homes in Simcoe County and Georgian Bay, radiant and ICF are a natural pairing — our partner icfhome.ca builds complete custom ICF homes with all HVAC engineering included.
- Room-by-room heat loss foundation (CSA F280)
- PEX loop layout over your floor plans
- Loop lengths & spacing calculations
- Manifold locations & zone mapping
- Supply water temperature targets
- Boiler or heat pump sizing
- CAN/CSA-B214 compliant design
- BCIN designer stamp & signature
Radiant floor heating works by warming the floor surface to a temperature slightly above room temperature — typically 26–29°C — and allowing heat to radiate upward. Unlike forced air that delivers heat in bursts from registers, radiant maintains steady, even warmth throughout the room at lower air temperatures. The result is genuine comfort: warm feet, no cold drafts, no dust movement, no noise.
But this comfort depends entirely on correct design. The amount of heat a floor can deliver per square foot is physically limited by the maximum safe floor surface temperature — 29°C in occupied areas per CAN/CSA-B214. If your home's heat loss is higher than what the floor can deliver at that temperature, no amount of boiler adjustment will fix it. The system will run continuously and still fail to heat the room on cold days. This failure mode is well-documented — for the Ontario cost context, read the real cost of hydronic radiant in Ontario.
This is why radiant design must start with your certified CSA F280 room-by-room heat loss calculation. Only when you know exactly how many BTUs each room loses per hour can you calculate the required floor surface temperature, confirm the floor can physically deliver that output, determine your PEX loop spacing, and select the right supply water temperature and boiler capacity. See our permit rejection guide for what happens when this foundation is missing from a permit submission.
Installing radiant without this calculation — based on rules of thumb, manufacturer recommendations, or square footage estimates — is the single most common reason radiant systems underperform in Ontario homes. The floor feels warm but the room never gets to temperature. Design first. Install second.
The right radiant system depends on your construction type, floor finish, and whether radiant is your primary heat source or a comfort supplement. We design for all three approaches.
Slab-on-Grade Radiant
PEX tubing embedded in a concrete slab — the most efficient radiant installation. Excellent thermal mass stores heat and releases it evenly. Requires insulation below the slab and at the perimeter. Ideal for ICF homes and new construction with concrete floors.
Suspended Slab / Gypcrete Overpour
Tubing installed between floor joists with a thin concrete or gypcrete overpour above. Lower thermal mass than a full slab but provides excellent heat distribution over wood subfloor construction. Common in multi-storey custom homes.
Staple-Up with Heat Transfer Plates
Tubing stapled between joists with aluminum heat transfer plates to distribute heat upward. Lower output capacity than slab systems — suitable only where heat loss is low and floor finish is tile or hardwood. Not recommended as sole heat source in Ontario Zone 6–7.
CAN/CSA-B214 sets the maximum floor surface temperature at 29°C (84°F) in occupied areas — the threshold above which prolonged foot contact becomes uncomfortable. In bathrooms, pool surrounds, and within 0.8m of outside walls, the limit rises to 33°C (91°F).
These limits directly constrain how much heat a radiant floor can deliver. At 29°C floor temperature with a 22°C room target, the floor delivers approximately 27–32 BTU per square foot of floor area. If your room's heat loss exceeds this output, the radiant floor physically cannot heat the room on its own — and a supplemental heat source is required. This is why your CSA F280 room-by-room report must come first — not as a guess, but as a verified calculation for your specific home in your specific Ontario climate zone. Use our free design temperature tool to confirm your municipality's design day.
This is exactly why ICF construction pairs so well with radiant heating. The dramatically lower heat loss of an ICF wall assembly — typically R-25 effective versus R-20 for conventional framing — means room-by-room heat loss falls well within what a radiant floor can deliver at comfortable temperatures, using lower supply water temperatures that maximize boiler or heat pump efficiency.
| Zone / Area | Max Floor Temp | Approx. Output |
|---|---|---|
| Occupied living areas | 29°C (84°F) | 27–32 BTU/ft² |
| Bathrooms & wet areas | 33°C (91°F) | 35–42 BTU/ft² |
| Perimeter zones (0.8m from walls) | 33°C (91°F) | 35–42 BTU/ft² |
| Foyers & entryways | 33°C (91°F) | 35–42 BTU/ft² |
| Garages (unoccupied) | 35°C (95°F) | 40–48 BTU/ft² |
| Max allowed — any zone | 35°C (95°F) | Design limit |
Source: CAN/CSA-B214, Clause 14.2.1. Approximate output values assume 22°C room temperature and standard concrete slab with tile finish. Actual output varies by floor construction and finish.
A complete hydronic radiant design — from heat loss numbers to loop layout, manifold specification, and boiler sizing. Everything your installer needs to build the system correctly the first time.
Room-by-Room Heat Loss Foundation
Every radiant design starts with a certified CSA F280 heat loss calculation. We calculate how many BTUs each room loses per hour — the only accurate basis for determining loop spacing, supply temperature, and whether the floor can physically heat the room.
PEX Loop Layout Drawings
Full loop layout drawn over your floor plans showing tubing pattern, spacing, loop boundaries, and transitions between zones. Includes separation between loops, expansion joint locations, and perimeter details.
Loop Lengths & Circuit Sizing
Individual loop lengths calculated to maintain balanced flow and pressure — no loop exceeds 100m to prevent pressure drop and temperature variation. Each circuit is sized to deliver the required BTU output for its zone.
Manifold Locations & Zone Map
Manifold placement optimized for balanced loop lengths and accessible installation. Zone boundaries defined by room groupings, floor area, and thermostat control strategy.
Supply Water Temperature Targets
Design supply and return water temperatures calculated for each zone based on heat loss, tube spacing, and floor finish. Lower supply temperatures mean higher boiler efficiency — good design keeps supply temperatures as low as possible.
Boiler or Heat Pump Sizing
Heat source sized to the calculated system load — not oversized. Includes specification of mixing valve requirements, expansion tank, and integration with cold-climate heat pump systems where applicable. BCIN stamp included.
ICF Construction + Radiant Floor Heat — Why They Belong Together
ICF homes have dramatically lower heat loss than conventionally framed homes — typically 40–60% less. This lower heat loss per square foot means the floor can heat every room at comfortable surface temperatures using lower supply water temperatures, maximizing system efficiency. For the full heating system comparison in an ICF home, read icfhome.ca on the best heating systems for ICF homes.
- Lower room heat loss means radiant floor operates within comfortable temperature limits
- Lower supply temperatures (40–50°C vs 60–70°C) dramatically increase boiler efficiency
- ICF's thermal mass works with radiant's thermal mass for exceptional temperature stability
- No forced air means no dust, no noise, no uneven temperatures — maximum comfort
- Compatible with cold-climate heat pumps as the primary heat source
Questions specific to radiant design — for permit documentation questions see our Full HVAC Design and Ventilation Design pages. For what documents your municipality requires see our permit rejection guide.
Does radiant floor heating require a building permit in Ontario?
Yes — any new hydronic heating system requires a building permit in Ontario. The design must comply with CAN/CSA-B214 and must be documented in your permit application. If radiant is your primary heating system, you also need a CSA F280 heat loss calculation, a boiler sizing document, and depending on your municipality, a full mechanical drawing set. We produce all of these as part of your radiant design package. For municipality-specific requirements, see our areas we serve page.
Can radiant floor heating be the only heat source in an Ontario home?
Yes, but only if the design confirms the floor can deliver sufficient heat output at safe surface temperatures on your coldest design day. In a well-insulated home — especially ICF construction — this is typically achievable. In conventionally framed homes with high window area or in extreme climate zones like Muskoka (-28°C) or Northern Ontario, supplemental heat may be needed for perimeter zones. Our design confirms this before your installer commits to a system.
What floor finishes work with hydronic radiant heat?
Tile and polished concrete are ideal — they conduct heat readily and tolerate the floor surface temperatures well. Engineered hardwood works well when designed with appropriate temperature controls (most manufacturers specify a maximum surface temperature of 27°C). LVP and vinyl plank are generally compatible. Solid hardwood requires more careful design and temperature management. Carpet significantly reduces output and is not recommended over radiant — its insulation value can reduce floor heat output by up to 40%.
What is the difference between a combi boiler and a dedicated boiler for radiant?
A combi (combination) boiler provides both domestic hot water and space heating from a single unit — popular for smaller homes because it eliminates a separate hot water tank. A dedicated boiler serves space heating only and requires a separate hot water heater. For radiant systems in larger homes or those with high hot water demand, a dedicated boiler often provides more consistent heating performance. We specify the right heat source for your system load, hot water demand, and budget during the design process.
Can I use a heat pump as the heat source for my radiant system?
Yes — cold-climate heat pumps pair well with radiant floor heating, especially in well-insulated homes. The key requirement is that the heat pump must be able to deliver water at the supply temperature your radiant system needs — typically 40–55°C for a well-designed system in an efficient home. This is why heat pump sizing and radiant design work best when done together. Our design keeps supply temperatures as low as possible to maximize heat pump efficiency.
Do I need separate design for a snow melt system in my driveway or garage apron?
Yes — exterior snow melt systems have different design parameters than interior radiant. Supply water temperatures are higher, loop spacing is typically tighter, and the system must account for heat loss to the ground and atmosphere rather than to a conditioned space. Snow melt systems are governed by the same CAN/CSA-B214 standard and require their own calculations. Contact us if your project includes exterior snow melt and we'll confirm the scope and pricing.
A properly designed radiant system delivers decades of comfortable, efficient heat. A poorly designed one disappoints from the first cold snap. Get the design right before the tubing goes in.
- CSA F280 room-by-room heat loss foundation
- PEX loop layout drawn over your floor plans
- Loop lengths, spacing & circuit sizing
- Manifold locations & zone map
- Supply water temperature targets
- Boiler or heat pump sizing included
- CAN/CSA-B214 compliant · BCIN stamped
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Radiant floor heating is one part of a complete mechanical system. These services complete the picture.