Home / Services / Ductwork Installation & Modification
Residential · Sheet MetalDuctwork Installation & Modification
Ductwork installation and modification is the sheet-metal side of comfort: new supply runs and returns, a trunk resized for the airflow a heat pump needs, and the sealing and balancing that make an existing system deliver what the furnace is actually producing. It is separate work from duct cleaning, and it is what fixes rooms a thermostat cannot.
Most of the duct problems we correct were designed in, not worn in. A 1950s or 60s bungalow off Plains Road or on the Hamilton Mountain typically got one large central return in the hallway and short supply runs to the near rooms, which worked when the furnace was a slow, oversized octopus. Add a finished basement, a rear addition and a bedroom door that stays shut, and the same system starves half the house. Adding a return in the primary bedroom and re-sizing two branch runs usually does more for comfort than any equipment change costing three times as much.
The number that tells us what is wrong is total external static pressure. Most residential furnaces and air handlers are rated for about 0.5 inches of water column; we measure across the blower and routinely find 0.9 or higher on systems with a high-MERV filter jammed into a slot sized for a fibreglass one, undersized returns, or a flex run crushed behind a soffit. High static is why blower motors burn out early, why registers whistle, and why the far bedroom gets a trickle — and it is a reading we can hand you, not a judgement call.
Ductwork is also the hidden line item when a house moves to a heat pump. A heat pump moves more air per unit of heat than an 80% furnace ever did, so a trunk that was fine at low airflow becomes the limiting factor at 400 CFM per ton. We measure before quoting equipment, and if the answer is that the duct needs a larger trunk section, a second return or new boots, we would rather say it before the system is ordered than after you notice the difference. Costs vary widely by house — how much ductwork costs sets expectations.
New runs get sealed with mastic at every joint, not cloth tape, which dries out and lets go within a few years in a warm basement. Basement and addition work is the bulk of what we do here: HVAC for finished basements and HVAC for home additions cover those two jobs in detail, and our residential HVAC page covers the rest of the house. To have someone measure yours, book a visit.
Duct modification is the fix when
- One or two rooms never reach temperature while the rest of the house is fine
- The upstairs bakes in July even with the AC running flat out
- Registers whistle, doors swing on their own, or the return grille roars
- You are finishing a basement, adding a room, or moving a wall the ducts run through
- A new furnace, air handler or heat pump needs more airflow than the existing trunk can pass
How it works
Static pressure at the blower, airflow at the registers, a look at the trunk sizing, returns, filter slot and any flex that has been crushed or kinked. You get the readings, not an opinion.
We lay out the new runs, take-offs, returns and balancing dampers on paper first, sized to the airflow your equipment needs, and quote it in writing before any metal is cut.
Trunk and branch work installed, joints sealed with mastic, boots and registers set, then the system balanced and re-measured so the numbers at the end are better than the numbers at the start.
Common questions
Is this the same as duct cleaning?
No. Duct cleaning removes dust and debris from ducts you already have. Duct installation and modification changes the ducts themselves — new runs, bigger trunks, added returns, sealing and balancing. Cleaning a badly designed duct system leaves it badly designed.
Can you add ducts to a house that has none?
Sometimes, and it is a bigger job than people expect: a boiler-heated house needs a furnace or air handler, a trunk route through the basement, and chases up to the second floor, usually taken out of closets. Where that is too invasive, a ductless mini-split does the same job with a 75 mm hole per room, and we will say plainly which one is the better buy for your layout.
Will adding a return really make a difference?
In older homes it is often the single biggest improvement available. Supply air pushed into a bedroom with a closed door has nowhere to go, so it pressurizes the room and slows the supply to a trickle. A dedicated return, or even a properly sized transfer grille, restores the loop.
Do I need a permit for duct work?
Straight repair and replacement of existing ductwork usually does not require one on its own, but duct work done as part of a furnace replacement, an addition or a basement finish is covered by the mechanical permit for that project. We pull what the job needs through the City of Hamilton or Halton Region.
How long does the work take?
Adding a return and re-sizing a couple of branches is often a single day. A basement or addition layout with new trunk sections is typically two to three days, and we schedule it around drywall so the metal goes in while the ceiling is still open.