The Short Answer

Polymeric siding expands when temperatures rise and contracts when temperatures fall. This movement is expected. A proper installation accommodates it through correct panel positioning, fastening and clearances at trim and accessories.

Why Temperature Movement Matters in the Quad Cities

Exterior cladding is exposed to more than the temperature shown by a weather forecast. Direct sunlight can warm a wall significantly, while shade, wind and overnight conditions can cool it. Different elevations of the same home may therefore experience different surface temperatures.

Dark colors and strongly sunlit walls may absorb more heat than lighter or shaded surfaces. That does not automatically make them unsuitable. It does make following the current product-specific installation instructions particularly important.

Iowa and western Illinois homes experience hot summers, cold winters and substantial seasonal temperature swings. An installation completed during cool weather must still perform when the panels become warmer, just as a warm-weather installation must accommodate later contraction.

How Fairhaven Sound Addresses Panel Positioning

Gentek identifies Fairhaven Sound as a polypropylene shake and scallop siding collection. According to Gentek, its installation-related features include self-aligning nail slots and a temperature chart on the panel’s side tab. These features are intended to assist with positioning for expansion and contraction in changing weather conditions.

These built-in features are useful, but they do not replace the complete installation instructions. The installer must still follow the current requirements for the selected profile, accessories, fastening surface and jobsite temperature.

• Self-aligning nail slots: Help establish consistent panel placement and fastening.
• Temperature chart: Helps the installer position panels for the conditions present during installation.
• Profile-specific construction: Means instructions should be checked for the exact Fairhaven Sound product being installed.
• Designed panel movement: Must remain available after the siding is fastened and connected to trim components.

Why “Tighter” Does Not Necessarily Mean “Better”

Homeowners sometimes assume that siding should be fastened as tightly as possible. Polymeric siding works differently. Its fastening slots are part of a system that allows controlled horizontal movement as temperatures change.

A fastener driven too tightly can restrict that movement. Fasteners placed incorrectly within their slots can also interfere with the panel’s intended response to temperature changes. The Polymeric Exterior Products Association, historically associated with Vinyl Siding Institute installation education, emphasizes correct fastener placement and allowing panels to move freely.

This does not mean the siding should be loose, unstable or carelessly attached. It means the fasteners and panels should be installed according to the manufacturer’s engineered method.

Expansion Space Is Also an Aesthetic Detail

Correct movement allowances support the finished appearance of the wall. If a panel is prevented from moving as designed, temperature changes may contribute to visible distortion, waviness or stress around joints and accessories.

Shake and scallop profiles naturally attract attention because of their texture, shadow lines and repeating shapes. That visual character makes alignment especially important. A well-planned installation should present deliberate courses, orderly corners and clean relationships with windows, doors, gables and rooflines.

Clearance at Trim, Corners and Openings

Panel movement must be considered anywhere siding meets another component. Examples include corner posts, window and door trim, utility penetrations, mounting blocks, roof intersections and transitions between siding profiles.

If the panel ends are crowded against an accessory, the available expansion space may be reduced. Conversely, excessive or poorly concealed gaps can weaken the finished appearance and may not comply with the installation requirements.

There is no single clearance number that should be copied into every project. Required spacing can depend on the product, temperature, panel location and accessory configuration. The current Gentek instructions for the specific Fairhaven Sound profile should govern the work.

The Wall Behind the Siding Still Matters

Expansion allowances cannot correct an uneven or improperly prepared wall. Before installation, the contractor should evaluate the substrate, water-resistive barrier, flashing and applicable wall details.

PEPA installation resources treat polymeric siding as part of a complete exterior wall assembly—not as a substitute for water management or structural preparation. Window flashing, penetrations and transitions must be detailed so water is directed away from vulnerable areas.

When exterior insulation is included, the attachment method must also account for the insulation thickness, fastening base and applicable installation requirements. This should be planned before materials are ordered.

Questions to Ask Before Installation Begins

A homeowner does not need to supervise every fastener. A short pre-installation conversation can, however, confirm that the crew understands the selected product.

1. Which Fairhaven Sound profile are we using? Confirm whether the design calls for Single 7-inch Straight Edge, Single 6-inch Traditional Shake, Single 8-inch RoughSawn Shake or 6-1/2-inch Scallop.
2. Do you have the current installation instructions? Product-specific requirements should be available to the installer, not recalled from a different siding line.
3. How will installation temperature affect panel positioning? Fairhaven Sound’s temperature chart should be used as directed by Gentek.
4. How will the panels be fastened? Ask how the crew will preserve designed panel movement while maintaining secure attachment.
5. How will transitions and penetrations be handled? Review windows, doors, light fixtures, hose connections, vents and changes between cladding styles.

What Homeowners Should Avoid

• Do not assume installation requirements for standard vinyl siding automatically apply to every polypropylene shake or scallop product.
• Do not rely on a universal expansion-gap number from an unrelated guide or online discussion.
• Do not caulk locations that are intended to permit drainage or panel movement unless the manufacturer’s instructions specifically require sealant there.
• Do not diagnose waviness from photographs alone. Sheathing, fastening, wall preparation, lighting and temperature can all influence what is visible.
• Do not make field modifications that could affect product performance or warranty coverage without consulting the applicable instructions.

A Better Way to Review the Finished Work

Review the project from several distances and under ordinary daylight. Close inspection is useful for trim and joint details, while a view from the street reveals whether courses, gable accents and color transitions feel visually balanced.

If something appears unusual, document the location and ask the installer to compare it with Gentek’s current instructions. Avoid pushing, pulling or refastening panels yourself because that can complicate both the diagnosis and any warranty discussion.