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Residential · New BuildsNew Construction & Addition HVAC
New construction and addition HVAC starts at the drawing stage, not on install day. The load calculation, the duct layout, the ventilation strategy and the vent terminations all have to be settled before insulation goes in — because after drywall, every one of them becomes expensive.
Residential equipment sizing in Ontario is done to CSA F280, a room-by-room heat loss and heat gain calculation based on the actual assemblies, window specifications and air-tightness of the building — not a square-footage rule of thumb. On a new build that calculation almost always comes out smaller than owners expect, because a house built to current envelope requirements loses far less heat than the one it replaced. Getting it right is what prevents the classic new-home complaints: a short-cycling furnace, an oversized air conditioner that cools without dehumidifying, and a bonus room over the garage that never matches the rest of the house.
Ventilation is the second design decision. Current construction is tight enough that it needs mechanical ventilation rather than the accidental leakage older houses relied on, and the compliance package your designer chose under the building code's supplementary standard largely determines the equipment efficiency and whether a heat recovery ventilator is part of the design. Do I need an HRV in Ontario explains the reasoning, and the unit has to be ducted and balanced at rough-in rather than hung on a wall at the end of the job.
Additions have the opposite problem from new builds: an existing system that was never meant to serve the new floor area. Before anything is designed we check whether the current furnace has spare capacity, whether the trunk can pass the extra airflow, and whether the existing vent terminations still meet clearances once a new wall goes up beside them — that last one is missed constantly and is caught at inspection. Sometimes the honest answer is that the addition wants its own system or a ductless head rather than a tie-in. New runs and resized trunks are covered on our ductwork installation page, and the rest of the house sits under residential HVAC.
The sequencing on site is rough-in before insulation and drywall — ducts, vent pipes, gas piping, line sets and low-voltage wiring — then finish work once the floors and ceilings are closed. Permits and mechanical inspections go through the City of Hamilton or the Halton Region building department depending on the address, and the mechanical inspection is booked against the rough-in, not the finished house. For budgeting, how much HVAC costs for a new build gives ranges — or send us the drawings through our contact page.
Bring us in at the design stage when
- You are building a custom home, a garden suite or a laneway house from scratch
- An addition, dormer or second-storey build is adding rooms the current system was never sized for
- A gut renovation is opening the walls and floors anyway, which is the cheapest time to redo ducts
- The basement is being finished and the mechanical room has to be relocated or boxed in
- The builder's base package needs upgrading before the walls close — a heat pump, a better filter cabinet, a second zone
How it works
We work from the plans: room-by-room heat loss and gain to CSA F280, equipment selection, duct layout, ventilation strategy and vent terminal locations, priced in writing before anything is ordered.
Trunk and branch ducts, returns, gas piping, condensate, refrigerant line sets, ventilation ducting and thermostat wiring — all installed and inspected while the framing is still open, coordinated around the electrician and plumber.
Equipment set, connected and commissioned, airflow balanced room by room, ventilation rate verified, permits closed with the inspector, and the manuals and warranty registration left with the owner.
Common questions
Do you work directly with builders and general contractors?
Yes, and also directly with homeowners acting as their own contractor on an addition or a gut renovation. What we need either way is the drawings and a realistic construction schedule, because rough-in has to land between framing inspection and insulation.
Can the addition just tie into my existing furnace?
Only if the calculation says the furnace has the capacity and the ductwork can carry the extra airflow. A 60,000 BTU furnace sized correctly for the original house has no spare capacity for a 400-square-foot addition, and forcing it means every room gets a bit less. We check first and give you both options with prices.
What does the builder's warranty cover on a new home?
New homes in Ontario carry statutory warranty coverage administered through the province's new home warranty program, with different terms for different components and defined windows for reporting. Tarion HVAC warranty on a new home explains what applies to heating and cooling and how long you have to report an issue.
My new build is a year old and something is wrong. Can you help?
Yes — second-opinion visits on builder-installed systems are common work, especially uneven rooms and short-cycling from oversized equipment. We measure airflow, static pressure and room-by-room temperatures and put the readings in writing, which is what turns a comfort complaint into a warranty claim the builder's trade has to answer.
Who pulls the permit?
We do, for the mechanical scope, and we book the inspections. On a full build the general contractor's building permit covers the project and our work is inspected under it; on a standalone equipment install we pull the mechanical permit ourselves.