Roof Penetration & Curb Installation Alberta

Commercial Roof Penetration & Curb Installation

Every pipe, vent, conduit, and rooftop unit has to pass through your roof, and each one is a hole in an otherwise sealed surface. In commercial buildings, penetrations and the curbs that carry equipment are where leaks start, far more often than at the open membrane. Commercial roof penetration and curb installation are their own trades.

Done poorly, one badly flashed pipe can soak the insulation around it for years unnoticed. Done right, the detail outlasts the rest of the roof. In Alberta, where metal expands and contracts hard between summer heat and winter cold, that care decides whether a curb holds or splits.

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Where Pipes, Vents, and Equipment Meet the Membrane

This service covers every spot where something protrudes from the roof plane: vent and plumbing pipes, conduit, exhaust fans, HVAC units, hatches, drains, and skylights. We install the flashing and curbs that seal those points, whether you are adding equipment, replacing a failed detail, or fixing work that was never watertight.

Each of these has to tie into your existing membrane without leaving a gap. A TPO or PVC roof needs welded boots; an SBS or built-up roof needs torch- or peel-and-stick detailing; and a metal roof needs counterflashing that allows for movement. Match the method to the roof, and the seal lasts; get it wrong, and you build a funnel into the insulation.

From Layout to a Sealed, Finished Detail

Planning the Opening and Layout

Before anyone cuts the roof, we plan exactly where the penetration or curb goes. That means coordinating with your mechanical and electrical trades so the opening aligns with the unit, duct, or conduit it serves.

We check the deck and structure can carry the load, confirm the spot clears existing drainage so water still runs off, and keep penetrations away from seams and low points where they would invite trouble. A few minutes of layout here prevents a curb that fights the roof and a detail that ponds water for years.

Cutting In and Building the Curb

With the layout set, we open the roof cleanly and build the support the detail needs. For a curb, that means a square, level frame anchored to the structure and tall enough to keep flashing well above the water line and snow.

We add insulation and a cover board to eliminate cold gaps and reinforce the deck where a heavy unit will sit. Clean cuts and solid framing matter because every later layer of waterproofing only works if the base under it is true. A leaning or short curb undoes the best flashing.

Flashing and Tying Into the Membrane

This is where the seal is made or lost. The flashing has to become part of your existing roof, not just sit on top of it. On TPO and PVC, we heat-weld boots and curb wraps into the field membrane. On SBS and built-up systems, we torch or adhere layered base and cap flashing.

Metal curbs get counterflashing detailed to allow thermal movement without opening a gap. Every termination is sealed and, where the system calls for it, fastened and stripped in. Matching the flashing to the membrane keeps the detail watertight for years.

Testing and Final Walkthrough

A penetration or curb is not finished until it has been proven to shed water. Where it makes sense, we run a controlled water test on the completed detail, then check the surrounding membrane and terminations again.

You get photos of the finished work and a clear record of what was installed and how it was sealed, which matters for both your warranty and any future inspection. We walk you through the result so nothing is a mystery. The aim is a detail you never have to think about again, through every Alberta season.

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What Goes Into a Detail That Holds

Not every opening is sealed the same way. A round plumbing or vent pipe takes a flashing boot sized and welded or wrapped to the membrane. Bundled electrical and gas conduit often needs a pourable sealer pocket or a custom curb. Large items like HVAC units, exhaust fans, and hatches sit on built curbs with their own flashing. Roof drains and overflow scuppers tie into the field with clamping rings and target sheets, and skylights need a curb plus counterflashing. We match the method to the item and the membrane, so each detail is built to seal rather than forced to fit.

A curb is only as good as its height and its anchoring. Build it too low, and spring snowmelt rises above the flashing line, turning the base of every rooftop unit into a soak point. We set curbs tall enough to clear the snow load Alberta roofs carry, and anchor them to resist the wind uplift that works at anything standing proud of the field. Counterflashing is detailed to allow the metal to expand and contract through the temperature swings here without splitting the seal. The result is equipment that stays dry through deep winter and the gusts that follow a chinook.

Most penetration and curb work happens on a building that is still open for business. Adding a rooftop unit or running new conduit means cutting into a roof that has to stay watertight overnight and through the next storm. We sequence the work so an opening is never left exposed, coordinate timing with your mechanical and electrical contractors, and protect the interior below. Where an old detail has been leaking, we strip it back to the sound substrate rather than seal over the problem. The point is to add what you need without handing you a new leak in return.

A penetration that was rushed rarely fails loudly at first. Water seeps in around the boot or under the curb flashing, spreads through the insulation, and quietly rots the deck while the surface still looks fine. By the time it shows inside, the repair is no longer a single boot; it is a wet section that has to come out. A botched detail can also void the membrane warranty, since manufacturers expect their own approved flashing methods. Getting the details right the first time is far cheaper than chasing the same leak across three winters.

What to Weigh Before You Cut Into the Roof

Cutting a hole in a sound roof is easy; making that hole disappear from a water standpoint is the hard part. The points below cover what comes up most when an owner needs new rooftop equipment, more conduit, or a fix for a detail that keeps leaking: who should do the flashing, how timing works, and how the right curb earns its keep.

Why the Roofer Should Flash, Not the Installer

When a new rooftop unit goes in, the mechanical crew makes the opening and sets the equipment, but flashing it into the roof is roofing work. Left to whoever is closest, that step gets a bead of caulk, and caulk is not waterproofing. A roofer ties the curb or boot to your specific membrane, sealing it the way it was meant to be sealed. That hand-off, done right, is the difference between a dry unit and a slow leak.

New Penetrations Versus Sealing Old Ones

Adding a penetration and fixing a failed one are different jobs. A new opening is planned, framed, and flashed from scratch. An old, leaking detail may only need its flashing rebuilt, but often the smarter move is to remove it entirely and patch the roof back to a clean field, especially if the equipment is gone. We tell you which path actually solves it rather than defaulting to the quickest patch.

Coordinating With Your Mechanical Trades

Rooftop projects rarely involve only the roofer. An HVAC swap brings a crane, a mechanical crew, and sometimes an electrician onto the roof in a set order. We coordinate so the opening is cut, the curb is built, the unit is set, and the flashing is finished in the right sequence, with no opening left exposed between trades. Clear scheduling keeps the job moving and prevents anyone from leaving a half-sealed hole overnight.

Timing Rooftop Work Around the Seasons

Weather shapes when this work goes best. Heat-welded and torch-applied flashing bonds most reliably in milder conditions, and cold can slow adhesives and stiffen the membrane. That does not mean rooftop work stops in winter, but planning it for the shoulder seasons yields the cleanest results. If equipment must go in during the cold, we adjust methods rather than force a detail that will not bond.

Keeping Water Moving Around Rooftop Units

A large curb in the drainage path acts like a dam. Water pools behind it, sits against the flashing, and seeps in over time. The fix is a cricket or saddle, a tapered build that splits the flow and steers it around the unit toward the drains. On Alberta roofs, where snowmelt arrives in volume, that diversion matters. We build the curb and the drainage detail together so the unit never becomes the low spot.

Commercial Roof Penetration & Curb Installation

Where Pipes, Vents, and Equipment Meet the Membrane

From Layout to a Sealed, Finished Detail

Planning the Opening and Layout

Cutting In and Building the Curb

Flashing and Tying Into the Membrane

Testing and Final Walkthrough

Have a new roofing project?

What Goes Into a Detail That Holds

What to Weigh Before You Cut Into the Roof

Why the Roofer Should Flash, Not the Installer

New Penetrations Versus Sealing Old Ones

Coordinating With Your Mechanical Trades

Timing Rooftop Work Around the Seasons

Keeping Water Moving Around Rooftop Units

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