An offset joint is a spot where two pipe sections don't line up. Debris can build up at the step, and if soil is exposed it can erode into the pipe and form a void. Seattle's utility says minor offsets need no repair, moderate ones need routine inspection, and severe ones should be repaired.
What an offset joint is
A sewer line is built from several segments of pipe connected by joints. Seattle Public Utilities says that when the joints do not perfectly match up, they are called offset joints. Put simply, the ends of two neighboring pipes don't meet squarely.
Why it matters
The utility names two problems. Offset joints can cause soil and debris to build up in the pipe and eventually lead to sewer backups. And if the joint is exposed, the soil around the pipe can wash away and leave an empty space. That space can be unstable and eventually lead to sinkholes.
For a commercial property, the second problem is the one to take seriously if the line runs under a parking lot, a driveway or a slab.
How severity is rated
| Rating | What the utility says | Recommendation |
|---|---|---|
| Minor | Buildup of debris is unlikely to cause any negative effects on the sewer system. | No repair. |
| Moderate | Causes some debris buildup, and typically would not cause a backup since there is no exposed soil around the joint. | Inspect after a few years. If there's no change, no repair is necessary. |
| Severe | Surrounding soil may erode into the pipe and lead to voids and cause a backup. | Should be repaired. |
Those are one utility's ratings for side sewers. On a PACP report, joint defects have their own family of codes, and Geocadra notes that they distinguish between offset, separated and angular joints. Each finding also gets a grade from 1 to 5, and Geocadra lists a small joint offset as an example of a Grade 1 finding (see what PACP coding is). Ask your inspector whether the offset shows exposed soil, since that's the fact that separates the "watch it" case from the "fix it" case.
What to ask about your report
- How far the joint is out of line, and whether the report includes a photo or a video timestamp.
- Whether soil or a void is visible at the joint.
- Whether roots are entering at the joint. Seattle notes that older pipes without watertight joints are especially at risk for root damage. See signs of tree roots in a sewer line.
- Whether a belly in the line sits nearby.
A cleaning can keep a line with a moderate offset flowing, but it doesn't change the offset. For the repair side, see what sewer line replacement involves.
HQ can scope the line, mark the location and go over the report with you. Free estimates and upfront pricing on any repair.