Siless Liner 157 (4 mm) Closed Cell Foam Sound Deadening - Thermal

In this review the Siless Liner 157 (4 mm) is evaluated as a practical, budget-friendly thermal and sound insulation mat for automotive projects. The single biggest reason to buy is its combination of closed-cell polyethylene foam and a full adhesive backing that delivers strong thermal blocking and lightweight waterproofing at a price much lower than similar materials. For installers who need a flexible, compressible liner to reduce radiant heat and damp vibration without a heavy overlay, this product is a straightforward solution.

Key Features

• Closed-cell foam: The polyethylene formulation is waterproof and oil resistant, so it will not absorb moisture or develop an odor in vehicle environments.
• Self-adhesive backing: A factory-applied adhesive layer makes installation easier and helps the material conform to metal surfaces for optimal thermal contact.
• Heat blocker: The liner is specified to block up to 98% of radiant heat transfer, reducing engine and exhaust heat intrusion into cabins and engine bays.
• Lightweight and compressible: At 4 mm thickness the foam is easy to handle, trim, and fit into tight cavities without adding significant mass.
• Temperature tolerance: The material shares operating temperature characteristics with rubber foam up to about 215 degrees Fahrenheit for typical automotive exposure.
• Value for money: With 36 ft2 per roll and a low per-square-foot cost compared with similar products, it is economical for large coverage jobs.

Who It's For

The Siless Liner 157 is best for car owners, DIY installers, and professional technicians who need a lightweight, waterproof thermal barrier for trunks, floors, doors, or engine bay shielding. It works particularly well when layered over butyl-based deadeners to combine vibration damping with radiant heat protection.

It is less suitable for users who require very thick multi-layer acoustic treatments or who need products rated for continuous exposure far above 215 degrees Fahrenheit; in those cases a higher-temperature or thicker specialized mat would be more appropriate.

Pros & Cons

Pros

• Effective radiant heat blocking and measurable interior temperature reduction when installed in engine bays or under carpeting.
• Waterproof closed-cell foam resists moisture and odor, making it durable in vehicle environments.
• Easy to trim and apply thanks to the self-adhesive layer and flexible 4 mm sheet thickness.
• Large 36 ft2 roll offers good value compared with pricier alternatives.

Cons

• Some customers report mixed experiences with stickiness and tearability, so heavy or repeated repositioning can be difficult.
• At 4 mm it provides less mass for low-frequency vibration damping than thicker multi-layer deadeners alone.

Specifications

Our Verdict

The Siless Liner 157 (4 mm) is a practical, cost-effective thermal barrier for automotive projects that need waterproof, lightweight insulation with easy installation. It is a smart buy for anyone wanting to reduce radiant heat and improve cabin comfort without paying a premium, though installers seeking heavy mass damping or extreme temperature ratings should consider complementary or alternative products.

Frequently Asked Questions

Is the liner waterproof?
Yes, the closed-cell polyethylene formulation and waterproof adhesive prevent moisture absorption and resist odor.

Can it be used in engine bays?
Yes, it is used to block engine and exhaust heat, but keep long-term temperature exposure below about 215 degrees Fahrenheit.

How much coverage does one roll provide?
One roll covers 36 ft2 and measures roughly 15.74 in by 330.7 in.