Fiberglass vs felt liners in CIPP rehabilitation

Fiberglass vs felt liners in CIPP rehabilitation

Not all liners used in CIPP pipe rehabilitation have the same structural behaviour. The two most common liner types are fiberglass liners (GRP) and felt liners, each with different characteristics, advantages and application limits.

Understanding this difference is important when choosing the right rehabilitation solution, especially when the objective is long-term performance and not only internal sealing.

Main differences between the materials

Fiberglass and felt liners differ mainly in structural strength, rigidity, dimensional stability and durability.

Fiberglass liners (GRP) usually offer:

• high mechanical resistance

• defined structural behaviour

• greater dimensional stability

• high long-term durability

Felt liners usually offer:

• greater flexibility

• easier adaptation to irregular pipe geometry

• more limited structural behaviour, depending on the system

• lower rigidity after curing

Structural rehabilitation vs lining

The choice of liner must always be linked to the objective of the intervention. A fiberglass CIPP liner is normally used when the aim is structural rehabilitation, creating a new pipe inside the existing one with defined mechanical performance.

Felt liners may be suitable for specific applications, particularly where flexibility is important or where the structural requirement is lower.

Typical applications

Fiberglass liners are especially suitable for:

• vertical stacks with structural degradation

• buried pipelines

• branches requiring structural reinforcement

• situations where high durability is required

Felt liners may also be used in specific contexts, depending on pipe condition, diameter, access and the intended rehabilitation method.

Durability and performance

CIPP rehabilitation with fiberglass liners can provide an estimated service life of 40 to 50 years, when correctly designed, installed and cured. It offers strong mechanical performance and good chemical resistance.

The performance of felt liners can vary depending on the liner system, resin type, installation method and pipe conditions.

Choosing the right solution

The decision between fiberglass and felt should be based on a technical assessment of the pipe, including:

• structural condition of the pipe

• type and severity of defects

• length of the section to be rehabilitated

• network use and operating conditions

A correct technical decision helps ensure not only that the immediate problem is solved, but also that the rehabilitation remains reliable over time.

A technical decision, not only a material choice

More important than the liner material itself is selecting the correct system for each situation. CIPP technology allows different approaches, and the right choice should be based on diagnosis, pipe condition and performance requirements.

Technical clarity in pipe rehabilitation

The distinction between fiberglass and felt is an important part of CIPP rehabilitation. Understanding these differences helps clients make better decisions and supports more consistent, durable results.

If you need to assess which solution is suitable for your pipe system, REVIPOX can perform a CCTV inspection and recommend the most appropriate approach, whether epoxy lining or CIPP rehabilitation.