Mechanical Drawings Ontario: What Building Departments Want to See Before They Stamp the Permit
A heat loss number is the foundation. Mechanical drawings are everything built on top of it. They show the reviewer where the air goes, how the house breathes, and whether the system was actually designed or just assembled from habit. This page explains what goes on a complete Ontario mechanical drawing set, who needs one, and how all the pieces connect.
If you just need the short answer: start with our CSA F280 heat loss calculation, then see our full HVAC design package for the complete permit-ready drawing set. If you want to understand why, keep reading.
Ontario building reviewers aren't just checking that you have a furnace. They're checking that the system was designed — that someone looked at the house, understood how it works, and made deliberate decisions about how air and heat move through it. Each layer of the drawing package answers a specific question the reviewer will have. For the full explanation of what Ontario municipalities require and why, read our guide on permit rejection causes.
The Load Calculation (CSA F280)
The foundation layer. Before anything gets drawn, the CSA F280 heat loss calculation establishes how many BTUs each room loses on the design day. This number determines equipment size, duct sizing, room-by-room airflow, and whether the system can actually keep the house comfortable on the coldest night of the year in your municipality. Every other drawing in the package flows from this number. Without it, the drawings are decoration.
The Duct Layout Plan
The most visual layer — and the one reviewers spend the most time on. The duct layout shows supply register locations drawn over the floor plan, return air strategy, trunk and branch duct routing concept, and room-by-room CFM assignments. A reviewer looking at this should be able to trace the air path from equipment to register and confirm that every conditioned space is served. Missing registers, undersized returns, and unserved rooms are all visible on a good drawing and invisible on a bad one.
The Ventilation Design (MVDS)
Mandatory since OBC 2024 took effect on January 1, 2025. The Mechanical Ventilation Design Summary documents your HRV or ERV system — Total Ventilation Capacity calculation per CAN/CSA-F326, room-by-room supply and exhaust assignments, SRE confirmation at operating airflow, and the SB-12 energy compliance path. This is the layer most often missing from packages prepared by designers who haven't updated their templates since 2012. Building departments across Ontario are actively enforcing it.
The Equipment Schedule
A table identifying the main mechanical equipment — furnace or air handler, cold-climate heat pump if applicable, HRV or ERV, supplemental heating if required — with each piece sized from the load calculation. The schedule shows capacity, model or specification, and the design data it's matched to. It's the layer that confirms equipment selection was an engineering decision, not a supplier recommendation chosen before anyone did the math.
The Schedule 1 Declaration
The legal layer. The Schedule 1 is a form — separate from the drawings — in which the BCIN-registered designer declares they have taken professional responsibility for the HVAC design. It must include the designer's name, BCIN registration number, qualification ID, and original signature. It must be submitted alongside every other document. A package missing the Schedule 1 is returned before a reviewer reads anything else. It is the most preventable rejection on the list.
Radiant or Hydronic Drawings (Where Applicable)
Projects using radiant floor heating require additional layers — PEX loop layout drawings, manifold locations, zone mapping, and supply water temperature targets. These coordinate with the rest of the mechanical package rather than replacing it. Radiant doesn't remove the need for the first five layers — it adds to them. For ICF homes specifically, the load characteristics change the radiant design significantly; see our partner icfhome.ca on radiant floor heating for the ICF-specific context.
A complete mechanical drawing package tells a single coherent story: here is the load, here is the equipment, here is where the air goes, here is how the house breathes, and here is the designer who is professionally responsible for all of it. When every layer is present and consistent, the permit moves. When any layer is missing or inconsistent, it doesn't. That's the entire logic of the package.
The most common question we get is some version of "do I need the drawings or just the heat loss calculation?" The honest answer depends on your project and your municipality.
A standalone heat loss report may be sufficient for: simple renovations with no major mechanical changes, small additions where the existing system serves the addition, and some straightforward new homes in municipalities with minimal documentation requirements. The right way to find out is to ask your building department — or use our areas we serve guides for your municipality's specific expectations.
A full mechanical drawing package is typically required for: new custom homes in most Ontario municipalities, projects using heat pumps or hybrid systems where the reviewer wants to see equipment sizing logic, homes with complex mechanical systems (radiant + forced air + HRV), and any project where the building department has asked for "mechanical drawings" or "HVAC layout."
The practical reality is that most new custom homes in the Simcoe County, Georgian Bay, and Muskoka area need a full package. The municipalities we work with most — Barrie, Collingwood, Oro-Medonte, Midland, Wasaga Beach, Tiny Township, and the six Muskoka area municipalities — all expect to see more than a heat loss number. For how to get a building permit in Ontario generally, the Ontario building permit guide at buildersontario.com is the best plain-English resource.
Projects that consistently need the full package
- New custom homes — anywhere in Ontario
- Homes using cold-climate heat pumps as primary heat
- Hybrid heating systems (heat pump + gas backup)
- Homes with radiant floor heating as primary system
- Mixed systems: radiant + ducted air + HRV
- Permit files where the municipality asked for HVAC drawings
- ICF homes — lower loads need correct equipment matching
- Any home where the permit office bounced a previous submission
"The installer will figure it out on site." Sometimes they do. Sometimes they don't. And sometimes "figure it out on site" means a system that costs twice as much to operate, struggles on cold nights, and fails its permit inspection. Mechanical drawings cost a fraction of a day's labour. The conversation about why the system doesn't perform correctly costs considerably more.
This is the part most people don't see until a permit reviewer flags an inconsistency: the layers of a mechanical package have to agree with each other. A load calculation that shows 28,000 BTU/h total heating load should produce an equipment schedule with a furnace or heat pump in a coherent capacity range. A duct layout showing four bedrooms should produce a ventilation design with supply air to four bedrooms. These are not independent documents — they're a single design expressed in multiple layers.
| Layer | What Inconsistency Looks Like | What Consistency Looks Like |
|---|---|---|
| Load calc vs equipment schedule | 70,000 BTU furnace on a 28,000 BTU load | Equipment capacity matched to calculated load with appropriate design margin |
| Duct layout vs room loads | High-load bonus room with one small register | CFM assignments proportional to room-by-room heat loss |
| Ventilation vs bedroom count | TVC calculated for 3 bedrooms on a 5-bedroom home | TVC reflects actual bedroom count and habitable spaces |
| Equipment schedule vs MVDS | HRV specified at 40% SRE on an SB-12 Tier 2 path | HRV/ERV SRE confirmed to meet the specific SB-12 compliance path for this home |
| Schedule 1 vs report date | Schedule 1 signed before the drawings were revised | Schedule 1 reflects the final version of all submitted documents |
A reviewer who sees an oversized furnace on a tight envelope will question the load calculation. A reviewer who sees a TVC that doesn't match the bedroom count will question the ventilation design. Inconsistencies don't just get the flagged layer returned — they call the entire package into question. Coordinated packages move. Inconsistent packages generate questions that can take weeks to resolve. See our full HVAC design package for how we produce coordinated, complete submissions.
The drawing package structure is the same for every project — load, duct, ventilation, equipment, Schedule 1. But what goes on each layer changes significantly depending on the heating system.
Forced Air — Furnace or Heat Pump
The standard package applies directly. Duct layout, supply/return strategy, equipment schedule, HRV integration. The full five layers. For cold-climate heat pumps, the equipment schedule must show rated capacity at the local design temperature — not the nominal capacity at +8°C.
Radiant Floor + Ventilation
Radiant replaces the duct layout with PEX loop drawings — but the load calculation, MVDS ventilation design, and equipment schedule still apply. You still need HRV/ERV documentation regardless of heating type. See our radiant design service for how these layers combine.
Hybrid Systems
Hybrid setups — cold-climate heat pump with gas backup, heat pump with electric resistance, or heat pump with radiant — require the most careful coordination. The drawing package must show how the systems interact, what conditions trigger each heat source, and how backup heat is sized relative to the primary system load.
ICF Homes
ICF construction changes the load calculation inputs significantly — R-25 effective walls versus R-20 conventional framing means a meaningfully different heat loss profile. For custom ICF builds across Georgian Bay and Simcoe County, our partner icfhome.ca coordinates the full build with all HVAC engineering included.
The process is the same whether you need a standalone heat loss report or the full drawing package. It starts with your plans and ends with stamped documents ready for your municipality's portal.
Upload Your Plans
Floor plans, elevations, sections, window schedules, insulation details — everything you have. Any format. We identify what we need. Start here →
We Confirm Scope
We review the plans and your municipality's specific requirements — portal type, pre-conditions, OBC 2024 compliance path — and quote a flat rate within 24 hours.
We Build the Package
Load calculation, duct layout, ventilation design, equipment schedule, and Schedule 1 — all coordinated and consistent. Production starts immediately after payment.
You Receive Stamped PDFs
BCIN-stamped documents delivered by email in 48 hours — formatted for your municipality's portal and ready to submit.
What's the difference between mechanical drawings and a heat loss calculation?
The heat loss calculation tells you how much heating the house needs. The mechanical drawings show how the selected equipment and distribution system are laid out to serve that load. One is the calculation. The other is the system designed from the calculation and drawn to show the reviewer how it all works. Most Ontario new home permits need both — the calculation alone is the foundation, but the drawings are the house built on top of it.
Does every Ontario building permit require mechanical drawings?
Not always. Some simple renovations and additions only need a heat loss report. But most new custom homes in Ontario require a more complete mechanical package — particularly if the project uses a heat pump, radiant system, or hybrid setup, or if the municipality has asked for "HVAC design" or "mechanical drawings." Check our local municipality guides for what your specific building department expects. Our permit rejection guide covers the most common gaps.
What is the Schedule 1 and why does it keep getting mentioned?
The Schedule 1 is a separate form — not part of the drawings themselves — in which the BCIN-registered designer declares professional responsibility for the HVAC design. It must include the designer's name, BCIN number, qualification ID, and original signature. It must be submitted alongside every other document. Missing or unsigned Schedule 1s are one of the most common reasons permit applications are returned before a reviewer even reads the technical content.
Does the Mechanical Ventilation Design Summary (MVDS) have to be part of the drawings?
Yes — since OBC 2024 came into force on January 1, 2025, the MVDS is mandatory for all new Ontario residential construction. It documents the HRV or ERV system — airflow rates, Sensible Recovery Efficiency at -25°C, and SB-12 compliance path. If your designer's package doesn't include it, they're working to the wrong code. Every package we produce includes the MVDS as a standard component.
Can I get just the duct layout without the heat loss calculation?
We don't produce duct layouts or equipment schedules without a supporting load calculation, because the drawings would have no technical basis. A duct layout not grounded in a room-by-room load is guesswork dressed up as engineering — and an experienced reviewer will identify it as such. The load calculation is always the starting point. It can be one we produce or one produced by another qualified designer.
How do mechanical drawings for a radiant system differ from a forced-air system?
The load calculation, ventilation design, and equipment schedule layers apply to both. What changes is the distribution layer — instead of a duct layout, you get PEX loop drawings with loop lengths, spacing, manifold locations, and supply temperature targets. The MVDS is still required because radiant doesn't replace ventilation. The two drawing packages cover the same permit requirements through different distribution strategies.
What if my municipality asked for mechanical drawings but I already have a heat loss report from another designer?
That's one of the most common reasons people contact us. If you already have a heat loss report you're happy with, we can produce the remaining drawing layers — duct layout, MVDS, equipment schedule, and Schedule 1 — as an add-on. We'll review the existing report first to confirm the design temperatures and room loads are correct before building the rest of the package on top of it. Contact us with the existing report and we'll confirm the scope.
How long does it take to get a complete drawing package?
48 hours after payment for a standard new home permit package. We've served projects from simple bungalows to complex multi-storey custom homes, and the 48-hour commitment holds across all of them. Complex projects with radiant + forced air + HRV combinations occasionally require a brief scope confirmation call before production begins — but the quote and confirmation happen within 24 hours of receiving the plans.
Upload your floor plans and tell us your municipality. We'll confirm what your building department requires, produce the complete coordinated package, and deliver BCIN-stamped documents ready for your portal within 48 hours. For ICF custom home builds with all engineering included, visit our partner icfhome.ca/build-with-us.
- CSA F280 heat loss — room by room
- Duct layout drawn over your floor plan
- MVDS ventilation design — OBC 2024 compliant
- Equipment schedule sized from the load
- Schedule 1 signed and stamped
- Formatted for your portal in 48 hours
Drag & drop your floor plans here
PDF, CAD, JPG, PNG — any format works