What a vent pipe actually does
Think of pouring from a can with one hole punched in the lid. Glug, glug, slow. Punch a second hole and it flows smoothly. A drain works the same way. As water drops down the pipe, it needs air behind it, and the vent provides that air.
The vent has a second job. Each sink, tub and toilet has a curved trap that holds a plug of water. That water plug blocks sewer gas. When a draining fixture pulls too hard on the line, it can siphon the trap dry, and the smell walks in. A working vent keeps pressure balanced so the plug stays put.
Signs the venting is wrong
These show up in older homes, remodels and additions most often.
- Gurgling after a fixture drains.. The sound is air being pulled through the trap because it has no other path. A tub or washer draining is a common trigger.
- Slow drains with no clog.. If a snake does not help and the line is clear, the vent may be the problem.
- Sewer smell near a fixture.. Especially one that sits unused, or one at the far end of a long run. A dry or siphoned trap is the usual cause.
- Toilet bubbles when something else drains.. Water and air are fighting for the same path.
- A new bathroom or basement fixture that never drained right.. Added fixtures sometimes get connected to the drain without a proper vent.
Before assuming the vent is bad, rule out a plain clog. A blocked drain and a blocked vent can cause overlapping symptoms, and a camera or snake test sorts them out. Our drain cleaning service is often the first step before any roof work.
Common vent setups and where each fits
| Vent type | How it works | Where it shows up |
|---|---|---|
| Through-roof stack | A pipe rises through the roof and opens to outside air | Most homes, the main vent for the system |
| Individual vent | One fixture gets its own vent line | Fixtures far from the main stack |
| Wet vent | One pipe carries both drain water and air for nearby fixtures | Some bathroom groups, where the layout allows |
| Air admittance valve | A one-way valve lets air in without a roof penetration | Remodels and islands, only where local code accepts it |
Whether an air admittance valve is allowed, and where, depends on the plumbing code your town has adopted. We will not install one on a guess. We confirm the local rule first.
How a new vent gets installed
Trace the existing drain and vent
We open access where needed, find where each fixture ties in, and identify what is missing or undersized.
Plan the route
The new vent must rise before it goes horizontal, avoid chimneys and windows, and reach outside air. Walls and attic space decide the path.
Cut in and connect
We tie the vent to the drain at the correct point and run pipe up through the wall or chase.
Go through the roof
The pipe exits through a flashed penetration, then gets sealed so rain stays out. Winter frost can close a small opening, so the exit size matters in this climate.
Test and close up
We test the drain and watch each trap. Then we patch drywall access and leave the pipe clean and labeled.
Planning a bathroom, basement fixture or remodel that needs venting? We can look at the layout and price it clearly before work starts.
Call (847) 281-8626Why this is not a weekend project
A vent that exits too close to a window, ends below another roof, or connects at the wrong point can pull sewer gas into the home. The pipe must also slope so condensation drains away. Mistakes hide behind drywall and show up months later as a smell.
Work through the roof carries its own risk. Flashing that is not sealed correctly leaks into the attic. Our plumbing installation crew handles the pipe and the roof exit together, so there is one party responsible if something drips. We do not do roofing, so when a roof needs more than a flashed penetration, we say so and you bring in a roofer.
How housing age changes the vent picture
North Chicago's median home was built about 1973, and roughly a third predates 1960. Older houses may have vents that were routed through walls later opened for remodels, or fixtures added without new vent lines. Expect surprises behind old plaster and in basement bathrooms.
Newer housing is not immune. In Gurnee, the median home dates to about 1992, and most of the stock went up after 1980. A newer home is more likely to have a clean vent layout, but finished basements and added bathrooms can still outrun it. In Libertyville, a median build year of about 1976, roughly 28 percent of homes built before 1960 and a historic downtown core mean vent runs can be anything from tidy to improvised.
Permits, licenses and the paperwork around a vent
What North Chicago, Libertyville and Gurnee publish about plumbing work
North Chicago's building department page lists the Illinois Department of Health Plumbing Code among its adopted codes. The page does not describe a plumbing permit process, so ask the department directly at 1850 Lewis Avenue before adding or moving a vent.
The city also posts a plumber registration application and a contractor registration packet, and it lists plumbers as exempt from the city business license because they are state licensed. The Illinois Department of Public Health licenses plumbers under the Illinois Plumbing License Law, and its website has a license lookup.
Libertyville's village code adopts the Illinois Plumbing Code, and the village building division asks for a copy of the state plumbing contractor registration, the plumber's license and a signed letter of intent for each project. Gurnee's Building Safety Division applies a similar approach on water heater permits, requiring a registered plumber and a letter of intent. Before any wall or roof is cut, call JULIE at 811 if the work involves digging.
What not to do about a suspected vent problem
- Do not keep running drains if you smell sewer gas, open a window instead
- Do not cap, plug or stuff a vent pipe on the roof
- Do not climb onto a wet or icy roof to look
- Do not ignore headaches or dizziness with a gas smell, leave the building and call the gas utility or 911
Venting questions, answered
No. A bathroom exhaust fan moves air out of the room. A plumbing vent connects to the drain line and ventilates the pipes. They are separate systems and should never share a pipe.
If a fan duct and a vent both end near each other on the roof, they should still be separate openings.
Yes, we are open 24/7. A drain that backs up or a sewer smell that fills a room is a call we take at any hour, and same-day appointments are available when schedules allow.
A permanent vent installation usually waits for daylight and an open roof, so we may stabilize the problem first.
The city's building department page does not describe a plumbing permit process, so we will not guess. Call the department and ask before work starts. A licensed plumber should also be able to tell you what they file.
Whoever does the work should be licensed by the Illinois Department of Public Health.
Sometimes, with a method the local code accepts, such as tying into an existing vent in the wall. A through-roof route is the traditional answer. We check the layout and your town's adopted code before choosing.
A finished ceiling or a chase can make the route harder, so plan the bathroom location with that in mind.
It depends on how far the pipe runs, how much wall or ceiling must be opened, whether the roof exit is easy to reach, and what the code requires for sizing. Access is the biggest variable.
We give a clear price before work starts, after we see the actual route.
Air in, gas out, drains running clear
Call us if your drains gurgle, your fixtures smell, or a remodel needs a new vent run. We are open 24/7.
Call (847) 281-8626