Duct Design Services Ontario: Calculated CFM at Every Outlet — Not a Contractor's Sketch
A duct design is not the same thing as a duct layout. Every HVAC contractor can sketch where ducts will run. Only a BCIN-registered designer can calculate how much air — in CFM — needs to be delivered to each room at design conditions, size every branch and trunk to deliver that CFM at the correct velocity, and document the return air system to prevent negative pressure. That calculated, documented layout is what a professional duct design produces. It is what makes the difference between a custom home that maintains setpoint temperature in every room on the coldest night of the year, and one that has a perpetually cold master bedroom and a whistling gap under the door.
Our duct design is produced from the room-by-room heat loss at your municipality's confirmed design temperature — not from rules of thumb. Every supply outlet gets a CFM target. Every branch gets a calculated diameter. Every return grille is sized to balance the system. The result is a BCIN-stamped mechanical drawing your permit reviewer accepts and your HVAC contractor can install from with precision. For the complete background on why duct design matters, see our benefits of professional duct design guide.
Our duct design service produces every document your Ontario building permit requires and every drawing your HVAC contractor needs to install a correctly balanced system.
CSA F280 Room-by-Room Heat Loss
Every duct design starts from the confirmed load at your municipality's OBC design temperature — not from square footage or rules of thumb. The room-by-room heat loss is what determines the CFM required at each supply outlet. Without the calculated load, every downstream duct sizing decision is an approximation. With it, every decision is derived from data. See our heat loss calculation service.
Mechanical Drawings With CFM Targets
Supply outlet locations drawn over your floor plans, with the CFM target at each outlet shown on the drawing. Trunk and branch duct sizes calculated to deliver the required CFM at velocities in the residential comfort range (500–700 FPM for supply branches). Equipment location, supply plenum, and all transitions and fittings documented. BCIN-stamped on every page. Ready for both permit submission and contractor installation.
Return Air System Design
Return air grille locations and sizes calculated to balance the total system CFM. Dedicated returns for closed rooms where door-gap return air is insufficient. Central return sizing to prevent the furnace or air handler from starving for air. The return air system is what most contractor sketches shortchange — and the source of most of the negative pressure, door-slamming, and comfort complaints in residential HVAC systems that were never properly designed.
Equipment Schedule
Furnace, heat pump, or air handler model and capacity confirmed at the local design temperature — not nominal capacity. For cold climate heat pumps, the confirmed output at your municipality's design temperature is documented. For multi-stage or modulating equipment, the staging strategy relative to the zone loads. For the full heat pump design picture, see our cold climate heat pump guide.
MVDS — Mechanical Ventilation Design Summary
Mandatory under OBC 2024 since January 1, 2025. The HRV or ERV selection, ventilation capacity, SRE at -25°C, and SB-12 compliance path. Included as standard in every complete package — the permit application will be returned without it regardless of how complete the duct design is. See our HRV/ERV design service.
Schedule 1 · BCIN Stamp Every Page
Signed Schedule 1 designer declaration included as standard. BCIN credentials — name, registration number, qualification ID — on every page of every document, not just the cover. The OBC requirement is explicit on both points. Applications with BCIN credentials on the cover page only are returned before technical review begins. See our HVAC permit requirements guide.
Upload Your Plans
Floor plans for all levels, wall assembly details, window schedule, your municipality, and preferred system type. Upload here — we review and send a firm flat-rate price within 24 hours.
We Confirm and Calculate
We confirm your municipality's OBC design temperature from climatic data — not regional defaults. We run the CSA F280 room-by-room heat loss. Every CFM target flows from this calculation.
We Design and Stamp
Supply outlet layout, branch sizing, trunk sizing, return air design, equipment schedule, MVDS — all drawn over your floor plans. BCIN-stamped on every page. Equipment confirmed at your design temperature.
48h — Permit-Ready
Complete package delivered by email in 48 hours. Ready for your Ontario building permit application. Ready for your HVAC contractor to install from. Ready to commission against.
While every forced-air system benefits from a calculated design, four project types make the difference between a calculated design and a contractor sketch most stark.
Custom Homes With Large Glazing
West-facing great rooms, two-storey entries, and significant south glazing produce room loads that vary dramatically from room to room. A whole-house average CFM leaves these rooms undersupplied in winter and overwhelmed in summer. The room-by-room load drives room-by-room CFM targets — which only a calculated design provides. See our AC sizing guide.
Cold Climate Heat Pump Systems
A modulating CCASHP responds to the actual CFM distribution in the duct system. Zone imbalances cause the heat pump to hunt between stages and short-cycle. A calculated duct design that matches each zone's CFM to its load gives the heat pump the balanced distribution it needs to modulate efficiently. See our heat pump guide.
Multi-Zone Systems
Multi-zone forced-air systems require each zone's duct design to be sized independently from that zone's load. An under-designed multi-zone system has zones that fight each other — one zone satisfying while another remains unsatisfied, causing the system to run longer than necessary and wear equipment faster. Calculated zone-by-zone duct design is the foundation of a functional multi-zone system.
Simcoe County & Muskoka Custom Homes
At -22°C to -28°C, a room undersupplied by 25% of its design CFM will fall several degrees short of setpoint on the coldest nights of the year. In Zone 6 and Zone 7, the consequences of an unbalanced duct system are more acute than in Zone 5 — the loads are higher, the design-day temperature is colder, and the margin for error is smaller. See our local guides for Barrie, Collingwood, and Muskoka.
What is included in your duct design service?
Our duct design service is part of our complete HVAC package — it is not sold as a standalone duct layout without the underlying heat loss calculation. The complete package includes: CSA F280 room-by-room heat loss at your local design temperature, mechanical drawings with supply outlet locations and CFM targets for each room, branch and trunk duct sizing, return air design, equipment schedule with capacity confirmed at your design temperature, MVDS, and Schedule 1. All documents are BCIN-stamped on every page and delivered within 48 hours. See our HVAC design and mechanical drawings service for the full package description.
Is a duct design required for an Ontario building permit?
For many Ontario municipalities — particularly for custom homes, heat pump systems, and complex multi-zone designs — BCIN-stamped mechanical drawings showing the duct layout are required as part of the building permit application. The specific requirements vary by municipality. Confirm with your local building department what mechanical documentation is required for your project. Our HVAC permit requirements guide covers the standard OBC 2024 requirements across Ontario.
Can my HVAC contractor do the duct design?
A contractor can do the duct layout — deciding where ducts will physically run. For a permit-required BCIN-stamped duct design with calculated CFM at each outlet, the contractor must also hold an active BCIN registration in the HVAC-House category, or engage a separate BCIN-registered designer. Most HVAC contractors do not hold a BCIN registration. Ask your contractor directly for their BCIN number before assuming they can produce compliant permit documentation. See our BCIN guide.
How long does a duct design take?
48 hours from payment confirmation for standard residential projects. You upload floor plans, wall assembly details, and window schedule — we review and send a firm flat-rate price within 24 hours. Upon payment, the complete BCIN-stamped package is delivered within 48 hours. No additional charges after the quote is confirmed. See our heat loss cost guide for Ontario duct design pricing context.
Do you provide duct design for radiant floor heating systems?
For pure radiant-only systems, duct design does not apply — the distribution system is hydronic, not ducted. We produce hydronic circuit plans, manifold layouts, and supply temperature targets for radiant systems under our radiant heating design service. Many Ontario homes with radiant primary heating also have a forced-air ventilation distribution system for the HRV — in that case, the ventilation duct layout is included in the MVDS documentation. See our radiant heating design service.
Upload your floor plans and we'll produce the complete calculated duct design — room-by-room heat loss at your confirmed design temperature, supply outlet layout with CFM targets, branch and trunk sizing, return air design, equipment schedule, MVDS, and Schedule 1 — BCIN-stamped on every page and delivered in 48 hours. For the full HVAC design service context, see our HVAC design and mechanical drawings service. For the background on why duct design quality matters, see our professional duct design guide. For ICF custom builds, our partner icfhome.ca serves all of Ontario.
- CSA F280 heat loss — every CFM target derived from confirmed loads
- Supply layout with CFM at each outlet — over your floor plans
- Branch and trunk sizing — correct velocities, no guesswork
- Return air design — balanced system, no negative pressure
- MVDS · Schedule 1 · BCIN stamp every page · 48h delivery