At a glance: Completed 2026-09-21: old flue stack removal & roof vent install on Kingsbury Boulevard, University City, MO 63130. Office: St. Louis, 314-429-6000.
A pipe that was not doing anything anymore
Older homes in University City were often heated by boilers or gravity furnaces that vented straight up through the roof. When those systems were replaced with modern high-efficiency equipment that vents out the side of the house, the old metal flue was frequently left in place. It no longer carries exhaust, but it still sticks through the roof, and every penetration is a place water can get in.
On Kingsbury Boulevard, the old flue stack had outlived its job. Its flashing was aging, its storm collar was weathered, and keeping it meant keeping a leak risk for no reason. The homeowner chose to have it taken out for good.
Why we did not just patch the hole
The easy way to remove a dead flue is to pull the pipe, nail a scrap of plywood over the hole and shingle over it. That works, but it throws away an opportunity. The hole is already cut, it already sits in the attic space, and most older two-story homes in 63130 do not have enough exhaust ventilation. Putting a vent in that spot gives the attic a way to breathe without cutting a new hole anywhere else.
So the work order called for removing the stack and installing a 750 vent in its place, a standard square box vent that lets hot, moist air escape from the top of the attic.
Removing the stack safely
The crew first confirmed the flue was disconnected below and no appliance still used it. That step matters. Capping a flue that a water heater still depends on would push exhaust back into the house. With that confirmed, the shingles around the pipe were removed, the old flashing and storm collar were pulled, and the pipe was lifted out of the roof.
Any section that dropped down into the attic was secured or removed so nothing was left loose above the ceiling.
Sealing the opening
Before the vent went on, the crew laid ice and water shield around the opening. This self-sealing membrane sticks to the deck, seals around nails and gives the area a second waterproof layer under the shingles. If the hole was larger than the vent throat, it was framed down so the vent would sit on solid wood on all sides.
Installing the 750 vent
The 750 vent is a low-profile box vent. The crew set its flange into the shingle courses so the top edge sits under the shingles above and the bottom edge laps over the shingles below. That way water running down the roof flows over the vent instead of under it. Each corner was nailed into the deck and the nail heads were sealed.
Shingling around the new vent
New shingles were cut in and woven around the vent to match the surrounding courses. When the job was done, the only thing visible from the street was a small, tidy vent near the ridge where the tall pipe used to stand. The roof looks cleaner and one leak risk is gone.
Why attic ventilation matters in University City
Many homes in University City were built in the 1920s and 1930s with steep roofs and small attics. In summer, an under-ventilated attic can reach well over 140 degrees, which bakes shingles from below and loads the air conditioning. In winter, warm, moist air from the house condenses on the cold deck and causes mold and rot. Adding exhaust at the top of the attic, paired with intake at the soffits, helps keep the roof deck dry and the shingles lasting longer.
Other roof penetrations worth a look
If your home has an old flue, a capped plumbing vent or a dead exhaust fan on the roof, it is worth having it checked. Each one has flashing that ages. We can remove abandoned penetrations, reflash ones still in use, or convert openings into ventilation where it makes sense.
Roofer near me in University City, 63130
If you are searching roofer near me in University City, our St. Louis crews work across 63130, 63124 and 63105 and know the older housing stock here, including slate, tile and steep asphalt roofs. Call 314-429-6000 for the St. Louis office or 1-800-564-6232 at any hour.
We will tell you whether a stack can be removed, whether a vent belongs in its place and what the repair costs before any work begins.
Backed by our workmanship warranty
The vent installation and repair on Kingsbury Boulevard are covered by our lifetime workmanship warranty. If water gets in through the work we did, we come back and fix it.
Signs an old flue is causing trouble
Rust streaks running down the roof below a metal pipe, a cracked rubber storm collar, water stains on an upstairs ceiling near a chimney chase, or a rattling cap in high wind are all clues that an abandoned flue needs attention. Because nobody uses it, these signs are easy to ignore until a ceiling stain shows up. A quick inspection tells you whether to reflash it or take it out.
Fall timing on Kingsbury
Doing this in late September meant the new vent was in place before the heating season, when warm, moist indoor air starts rising into the attic. That is exactly when an extra exhaust vent earns its keep.
What the crew did, step by step
- Confirmed the old flue was disconnected and no appliance still vented through it.
- Removed shingles, flashing and the storm collar around the stack.
- Pulled the flue pipe out of the roof and secured anything left in the attic.
- Framed the opening as needed and installed ice and water shield around it.
- Installed a 750 box vent in the opening, lapped correctly into the shingle courses.
- Wove new shingles around the vent and sealed the nail heads.
- Cleaned up the roof and yard and hauled away the old pipe.
Questions homeowners in University City ask about this repair
Can an old furnace flue be removed from the roof?
Yes, once it is confirmed that no appliance still uses it. The opening can then be closed or turned into a vent.
Why put a vent where the flue was?
The hole is already there, and most older homes need more attic exhaust. A vent adds ventilation without cutting a new hole.
What is a 750 vent?
It is a common low-profile square box vent that lets hot, moist air out of the top of the attic.
Is an abandoned flue a leak risk?
Yes. Its flashing and storm collar age like any other penetration, even if the pipe is not in use.
Do you do roof repair in University City?
Yes. Call our St. Louis office at 314-429-6000.
How long does flue removal take?
Most are done in a few hours as part of a one-day repair.