Material terminology can sound unnecessarily technical when a homeowner is mainly interested in color and curb appeal. In practice, accurate terminology makes product comparisons easier and prevents claims from one siding category from being incorrectly applied to another.

Gentek lists Fairhaven Sound in its shakes-and-scallops collection and specifies polypropylene construction for its Traditional Shake, Scallop, Cape Cod Shake and Hand-Split Shake profiles.

The Polymeric Exterior Products Association also recognizes polypropylene siding as a distinct polymeric-cladding category commonly manufactured to reproduce wood shakes, shingles, stone and brick.

Polymer Is the Family; Polypropylene Is the Material

The word polymer describes a broad class of materials. Polypropylene and polyvinyl chloride—commonly called PVC or vinyl—are both polymers.

Calling Fairhaven Sound a polymer shake is therefore accurate, but less specific. Calling it polypropylene provides the exact material description published by Gentek.

Why People Call Them Vinyl Shakes

“Vinyl siding” has become a familiar household phrase, and people sometimes use it to describe nearly any lightweight polymeric cladding. Search engines also reflect the language homeowners commonly type rather than the precise material listed in a manufacturer’s specifications.

A contractor, supplier or article may therefore use “vinyl shakes” when discussing the general product style. That shorthand becomes a problem when it is carried into technical claims about composition, testing, code treatment, installation or insulation.

Clear communication can accommodate both forms of language: “If you are searching for Gentek vinyl shakes, the Fairhaven Sound product you are likely considering is actually polypropylene siding.”

How Polypropylene Supports the Cedar-Look Design

PEPA explains that polypropylene siding is commonly formed through an injection-molding process that can closely reproduce wood shakes and shingles. This manufacturing approach supports shapes, textures and lower-edge patterns that would be difficult to create with a conventional horizontal siding profile.

Gentek uses those capabilities to create four distinct Fairhaven Sound profiles:

• Traditional Shake with a consistent single-course exposure and natural cedar texture
• Scallop with a repeating curved lower edge
• Cape Cod Shake with varied exposure across the panel
• Hand-Split Shake with deeper cedar-grain texture and a staggered lower edge

Gentek also uses varied molds to reduce obvious repetition and self-concealing side tabs intended to make connections less visually distracting.

Polypropylene Does Not Mean the Product Looks Like Plastic

Material composition and finished appearance are different questions. A polypropylene product can be designed specifically to reproduce the surface relief, shadow lines and irregularity associated with cedar.

Whether the finished exterior looks convincing depends on more than the base material. Important aesthetic factors include:

• Depth and quality of the molded texture
• Variety among repeated patterns
• Visibility of panel connections
• Profile selection
• Color and sheen
• Viewing distance
• Course alignment and trim details

A well-designed polypropylene shake installed carefully can create a warm, dimensional effect. A premium product installed without regard for pattern, proportion or transitions can still look mechanical.

How It Differs Aesthetically from Conventional Vinyl Siding

Conventional vinyl siding is commonly formed into longer horizontal profiles such as clapboard or Dutch lap. Those profiles emphasize continuous horizontal lines.

Polypropylene shake panels are designed to suggest many smaller pieces of cedar. Their lower edges, surface relief and shadow patterns create a more textured visual field.

This difference is why Fairhaven Sound often works well as an accent against horizontal siding. The contrast is not only a change in color; it is a change in scale, texture and rhythm.

Does Polypropylene Siding Have an R-Value?

Polypropylene cladding should not automatically be described as insulated siding. Gentek’s current Fairhaven Sound product information does not publish an insulation R-value for the shakes and scallops.

PEPA distinguishes polypropylene siding from insulated vinyl siding. Certified insulated vinyl siding includes permanently attached foam and carries a tested, labeled R-value. Fairhaven Sound is not presented by Gentek as that type of product.

Separately documented continuous insulation can be installed behind compatible polymeric cladding when the complete wall is properly designed. In that situation, the R-value belongs to the specified insulation or tested assembly—not to the Fairhaven Sound panel.

Product Standards and Third-Party Certification

PEPA owns the VSI Product Certification Program. The program uses independent certification bodies and provides pathways for product certification listings and product evaluation reports.

PEPA identifies ASTM D7254 as the industry performance standard associated with polypropylene siding. Certification can help verify that an identified product meets applicable performance criteria.

Homeowners should distinguish between three separate ideas:

1. A manufacturer statement describes what the manufacturer reports about its product.
2. A test standard establishes defined procedures and performance criteria.
3. Third-party certification verifies an identified product through an independent program.

Advertising that references an ASTM standard is not necessarily the same as a current third-party certification listing. Ask for the documentation applying to the exact product being purchased.

Why Accurate Terminology Matters During Installation

Installers should follow instructions for the exact product category and profile. Conventional vinyl siding and polypropylene shakes may differ in panel dimensions, locking systems, accessory details and fastening requirements.

Gentek states that Fairhaven Sound includes self-aligning nail slots and a temperature chart to help installers account for expansion and contraction. Those product-specific features should guide the work.

A crew should not substitute a remembered rule from another siding product when the current manufacturer instructions provide a different requirement.

Why Accurate Terminology Matters When Comparing Prices

Two estimates can appear to cover “shake siding” while specifying very different products. One may include polypropylene specialty shakes, another conventional vinyl siding and another natural cedar.

A useful comparison should identify:

• Manufacturer and complete product-line name
• Material category
• Exact profile and color
• Quantity and coverage
• Trim and accessory products
• Wall preparation and water-management scope
• Installation requirements
• Applicable warranty documentation

Questions to Ask a Supplier or Contractor

1. Is the quoted product vinyl, polypropylene, insulated vinyl or another material?
2. What is the complete manufacturer and product-line name?
3. Which Fairhaven Sound profile is included?
4. Is the selected profile and color currently available locally?
5. Which current manufacturer installation instructions apply?
6. Is the product listed through the VSI Product Certification Program?
7. Does the proposal claim an R-value, and which exact product supports it?
8. What trim, transitions and accessories are included?
9. What warranty documents will be provided?

Language Homeowners Can Trust