The Best Screws for Fiberglass

Fiberglass is strong, light, and corrosion resistant, but it can also be brittle at the surface. Using the wrong fastener can lead to cracking, delamination, or loose joints over time. Choosing the best screws for fiberglass means balancing holding power with a gentle, controlled installation method, and pairing the right screw design with the right backing hardware.

Whether you are fastening fiberglass panels to steel framing, assembling enclosures, or mounting hardware on a boat, Springs Fastener offers a wide range of industrial screws that perform reliably in fiberglass and composite materials.

What Makes Fiberglass Different From Wood or Metal?

Fiberglass behaves differently than wood or metal when you drive a screw:

• High strength, but brittle surface: Fiberglass is strong in tension and bending, but the gelcoat and top layers can chip or spider crack if overloaded locally.
• Limited ability to compress: Overtightening a screw can crush the laminate around the hole instead of simply pulling the joint tighter.
• Thermal and moisture stability: Outdoor or marine fiberglass will see UV, moisture, and temperature swings that demand corrosion resistant screws and washers.

Because of this, the best screws for fiberglass usually have sharp, well formed threads, are made from corrosion resistant materials (often stainless steel), and are installed with proper pilot holes and load spreading washers.

Best Screws for Fiberglass Panels and Enclosures

The right screw often depends on what the fiberglass is attached to and how frequently the joint will be serviced. Below are common options that work well in fiberglass applications.

1. Stainless self drilling screws into metal framing

If you are fastening fiberglass panels to steel or aluminum framing, stainless self drilling or Tek style screws are a popular choice. They drill their own pilot hole in the metal while pulling the fiberglass panel tight, which makes them efficient for repeatable installations.

• Use self drilling screws when fastening through fiberglass into metal studs, brackets, or frames.
• For enhanced corrosion resistance, especially in outdoor or marine environments, consider stainless steel self drilling screws.
• Pair them with EPDM bonded washers when you need a weather tight seal around the screw head.

Take care not to overtighten. Once the washer seats and the panel is snug, additional torque only increases the risk of crushing the fiberglass.

2. Thread cutting and thread rolling screws directly into fiberglass

In some assemblies, screws are driven directly into fiberglass instead of into a metal substructure. For those cases, thread forming designs help create a stronger, cleaner thread in the composite.

• Thread cutting screws are designed to cut a mating thread into harder or more brittle materials. Certain styles are often used in cast metals and composites where a clean, controlled thread is important.
• Thread rolling screws form a thread by displacing material instead of cutting it. In fiberglass and other composites, this can reduce loose chips and help create a strong, interference fit.

When using thread cutting or thread rolling screws in fiberglass, always pre drill to the recommended pilot size from your fastener specification, and use low to moderate driving speed to avoid heat buildup or chipping around the hole.

3. Machine screws with backing hardware for serviceable joints

Where you need to remove and reinstall fasteners repeatedly, through bolted joints often outperform direct screw into fiberglass. A typical stack up looks like this:

• Fiberglass panel or laminate
• Flat or bonded washer to spread load
• Machine screw passing through a drilled clearance hole
• Back side washer and nut, or blind threaded insert

Springs Fastener carries a wide range of machine screws, along with companion nuts and washers that allow you to build robust bolted joints in fiberglass assemblies.

If the back side of the fiberglass is not accessible, installing a rivet nut or insert in the laminate can provide a reusable internal thread. Our selection of blind threaded inserts is well suited for this type of connection.

4. Panel fasteners and nylon fasteners for specialized applications

For removable access panels or covers made from fiberglass, engineered panel hardware can improve ergonomics and serviceability.

• Panel fasteners provide quarter turn or tool less access, and are often used on enclosures, equipment housings, and inspection panels.
• Nylon fasteners offer non conductive, corrosion resistant fastening where you need electrical isolation or where metal hardware could print through thin cosmetic fiberglass skins.

Installation Tips For Screws in Fiberglass

Regardless of which screw style you choose, proper installation is critical for long term performance in fiberglass.

• Pre drill pilot holes: For most screws, drill a pilot hole that is slightly smaller than the screw’s minor diameter. This gives the threads material to bite without splitting the laminate.
• Support the back side: When possible, support the back of the panel with a block of wood or backing plate while drilling to minimize breakout.
• Use moderate speed and light pressure: High drill or driver speed can create heat and lead to chipping. Let the drill bit and screw do the work.
• Add load spreading washers: Flat washers or EPDM bonded washers help spread clamp load over a larger area and reduce the risk of surface cracking.
• Do not overtighten: Once the joint is snug and the washer is seated, stop. Extra torque rarely improves strength in fiberglass and often damages the material.
• Seal penetrations when needed: For roofs, exterior panels, or marine structures, pair screws with sealing washers or appropriate sealants to keep moisture out of the laminate.

Choosing Materials and Finishes for Fiberglass Projects

Environment is a key factor when choosing the best screws for fiberglass:

• General industrial and indoor applications: Zinc plated steel screws can be suitable where corrosion exposure is limited.
• Outdoor, high humidity, or marine applications: Stainless steel is usually the best choice. Our broad selection of stainless steel fasteners provides excellent corrosion resistance and long service life around fiberglass structures.
• Electrical and RF sensitive assemblies: Nylon or other non metallic fasteners help eliminate galvanic corrosion and reduce interference.

Work With Springs Fastener on Your Fiberglass Fastening Needs

Fiberglass projects often mix different substrates, hardware types, and environmental demands. If you are unsure which screw style is right for your application, the Springs Fastener team can help you evaluate your joint design and suggest appropriate options from our wide range of screws, washers, nuts, and specialty hardware.

Not seeing the exact fastener you need, or working on a large project with specific requirements? Use our Request for Quote form to share your specifications, or reach out through our Contact Us page. We will help you identify the best screws for fiberglass in your application and supply them quickly with bulk pricing options.