Short definition
Cured-in-place pipe (CIPP) is a polymer-resin-saturated fabric liner that’s inverted or pulled into an existing damaged pipe and then cured — by hot water, steam, or UV light — into a hard, structurally independent new pipe inside the old. CIPP is the dominant trenchless option for residential side-sewer repair when the host pipe is intact enough to anchor against.
What it is
A felt or fiberglass liner is saturated with epoxy or vinyl-ester resin, then introduced into the host pipe through a cleanout. Pressure inverts the liner against the pipe wall — like turning a sock inside out — and a heat or UV cure hardens the resin in place. Cure times for residential laterals are typically 4 to 12 hours.
The result is a new, jointless pipe inside the old one, slightly smaller in inside diameter but smoother and gap-free. CIPP installations are governed by ASTM F1216 and ASTM F1743, with NASSCO PACP standards for inspection. The technology has been mature since the 1990s.
Why it matters to a homeowner
CIPP is the cleanest option when an aging pipe has cracks, joint offsets, or root intrusion but its walls are still mostly intact. Costs in Seattle (2026):
- Residential CIPP: $85–$150 per linear foot.
- Total residential job: $4,000–$20,000 depending on length and access.
- Savings vs. open-trench dig-and-replace: roughly 30–50% once landscape, asphalt restoration, and traffic-control costs are factored in.
The key constraint: CIPP needs an intact-enough host pipe to anchor against. A fully collapsed sewer line can’t be lined — there’s no wall to press against. That’s where pipe bursting takes over.
When you’ll encounter this term
- Pre-purchase scope shows a root-intruded clay-tile lateral with intact walls — CIPP preserves the landscaping.
- The line runs under a driveway or under a mature tree — CIPP avoids re-doing what’s above.
- A short Seattle side-sewer easement makes open-trench work impractical — CIPP fits in tight ROW situations.
Common variants / not the same as
- CIPP vs. epoxy spray-coat. Spray-coat is a thinner application; CIPP is a structural liner. The industry uses both terms loosely under “pipe relining.”
- CIPP vs. slip-lining. Slip-lining inserts a smaller new pipe inside the old; CIPP forms the new pipe in place from a soft liner.
- CIPP vs. pipe bursting. Pipe bursting fragments the old pipe and pulls a new one through; CIPP keeps the old pipe and adds a layer inside.
- Felt-CIPP vs. fiberglass-CIPP. Felt is more flexible (curves easier); fiberglass is stiffer and longer-lived but rigid.
Common failure modes
- Wrinkles in the liner during inversion → restricted bore.
- Incomplete cure → soft spots, eventual leaks.
- Cannot anchor to a fully collapsed host — needs at least an oval-but-intact wall.
- Severe joint offsets can’t be bridged.
Washington note
Seattle Public Utilities (SPU) accepts CIPP for residential side-sewer repair. A permit is required (now SPU-issued as of October 1, 2025). Multiple WA contractors specialize: Complete Trenchless, Pipe Spy, and others. Tacoma and most King County jurisdictions also accept CIPP under similar permit rules.