Quick Answer:
If you notice a sewer smell while walking through the remodel area and worry the remodeler cut or capped a vent incorrectly, stay calm and start with a few simple checks: review the remodel plans for moved drains or vents, look for temporary caps left in floor drains or vent pipes, run water through any relocated fixtures and sniff around joints for leaks, confirm new fixtures have P-traps and vents, and check floor drains for construction debris that can cause trap loss. If the odor continues or you suspect a vent was modified, call a licensed plumber.
Why This Happens
Remodel work can change how drains and vents connect. Common causes of a post-remodel sewer smell include:
- Vents cut, rerouted, or temporarily capped during work so gases can’t escape properly.
- Dry or missing P-traps after fixtures are moved or unused for a while—traps are the water seal that blocks sewer gas.
- Construction debris lodged in floor drains that prevents the trap from holding water.
- Loose or leaking drain joints where odor can escape.
This situation is similar to other post-work odor problems homeowners see after repairs—see Smell after plumbing repair for related causes and checks.
Step-by-Step What to Do
1. Review the remodel plans and inspect areas where drains or vents were moved
Get the portion of the plans that shows plumbing changes and compare them to what you see on site. Walk areas where pipes were relocated—kitchen, bathrooms, utility rooms, basement and attic. Look for new holes, patched openings, or roof vent changes. Note any work that appears incomplete or finished with temporary materials.
2. Check for temporary cap plugs left in floor drains or vents
Floor drains and vent stacks are often capped temporarily during construction. Remove drain grates and look for rubber or plastic caps. In basements or mechanical rooms, unfinished vent stub-outs might be capped. Remove temporary caps and refill traps with water where appropriate.
3. Run water through relocated fixtures and smell joints for leaks
Turn on sinks, tubs, and toilets that were moved or reconnected. Let water run for a minute or two, then check under sinks and around visible joints while smelling for sewer odor. A leak or bad joint may release gas even if pipes appear connected. If you find a leak, shut off water to that fixture and call the plumber.
4. Verify that any new fixtures have proper P-traps and vents installed
Open cabinet doors and look under new sinks to ensure a P‑trap is installed and connected properly. For wall-mounted fixtures or relocated appliances, confirm there is a vent route back to the stack—unvented fixtures can siphon traps and allow sewer gas in. If you can’t see a vent connection, ask the remodeler to show where the vent leads.
5. Look for construction debris lodged in floor drains causing trap loss
Remove grates and inspect floor and shower drains for dust, drywall, tile spacers, or other debris. Even small amounts can prevent a trap from holding water or create a path for gas. Clear debris, flush the drain with water, and top traps up to restore the water seal.
What Not to Do
- Do not assume builders will catch venting errors—avoid sealing openings until you confirm correct vent connections; call a pro when odors start after new fixtures are installed or if a vent was modified during remodel.
- Do not plug or permanently seal unknown roof or wall openings yourself—you could block a necessary vent or create a new problem.
- Do not rely only on strong-smelling cleaners to mask the smell; they don’t fix vents, leaks, or missing traps.
When to Call a Professional
- If the smell persists after you refill traps and clear debris.
- If you find or suspect a vent was cut, capped, or rerouted during the remodel.
- If you detect sewage backup, strong continuous gas odor, or physical damage to drain piping or vents.
- When you’re unsure how drains and vents should tie into the system shown on the plans.
When in doubt, call a licensed plumber to inspect vent connections and test for leaks or improper venting.
Safety Notes
- Sewer gas can be unpleasant and may contain hazardous components. If the odor is strong indoors, ventilate the area—open windows and doors—and limit time spent in the space.
- If you suspect a large gas leak or weak health symptoms (headache, dizziness, nausea), leave the area and seek help immediately.
- Avoid mixing cleaning chemicals when flushing drains. Wear gloves and eye protection when removing debris from drains.
Common Homeowner Questions
- Why did the smell start right after the remodel?
Because vents or drains were moved, temporarily capped, or filled with debris during work—any of those can let sewer gas into the living space. - Will pouring bleach down the drain fix the odor?
No. Bleach masks odor temporarily and doesn’t restore venting or fix leaks; add water to traps and clear debris instead. - How quickly should I expect a plumber to respond?
If the smell is persistent or you suspect a vent was altered, contact a plumber the same day; sooner if the odor is strong or there are signs of backup.
More in this topic
For more related fixes and similar symptoms, see Sewer Gas Smell from Floor Drains.