Installers are always looking for ways to save costs and improve efficiency, but reusing solar hanger bolts can jeopardize safety and waterproofing. While it’s tempting to reinstall a bolt that looks intact, this practice risks system performance and could lead to costly failures and compliance issues. Here’s why certified best practice is to always use new hanger bolts for each installation.
1. The Role of Hanger Bolts in Solar Mounting Systems
Solar hanger bolts are dual-thread fasteners that anchor mounting structures to the roof — commonly used in tile, metal, and wood roof settings. They perform two essential jobs:
- Deliver strong, stable mechanical fixation for racks and rails
- Ensure watertight seals at each roof penetration
Because these bolts are exposed to repeated weather and mechanical loads, even minor wear or damage can create major risks for long-term reliability.
2. Why Reusing Solar Hanger Bolts Is Not Advisable
A) Thread Deformation and Grip Loss
Bolts cut into wood or metal the first time they’re installed, forming tight threads in the substrate. Removing the bolt can strip or deform these threads—leading to a weaker grip, reduced pull-out strength, and loose connections if reused.
B) Waterproof Seal Failure
Every installation relies on a crushed sealing washer (often EPDM) and fresh sealant for waterproofing. Removing and reinstalling the bolt destroys the washer’s compression and limits sealant adhesion—raising the risk of leaks and water damage
C) Corrosion and Metal Fatigue
Even stainless bolts may develop microscopic corrosion or fatigue during use, especially in harsh climates. These hidden defects weaken bolt strength over time, risking future failures if bolts are reused.
D) Manufacturer & Standard Compliance
Top mounting manufacturers and industry standards (DIN EN 1090, UL 2703) dictate hanger bolts as single-use items. Manuals from companies like K2 Systems and IronRidge advise:
“Do not reuse fasteners that have been previously installed or exposed to stress.”
This ensures proper torque, sealing, and project safety on every installation.
3. What to Do Instead: Best Installation Practices
| Step | Recommended Action | Why |
|---|---|---|
| 1 | Use new hanger bolts & washers | Guarantees grip & strength |
| 2 | Inspect roof substrate | Avoids reuse in weakened materials |
| 3 | Apply fresh sealant around penetrations | Keeps waterproofing intact |
| 4 | Torque bolts to manufacturer specs | Prevents overtightening or slack |
| 5 | Inspect fasteners annually | Early detection of corrosion or loss |
By following these steps, installers protect both system reliability and long-term maintenance costs.
4. Common FAQs About Reusing Hanger Bolts
Q1: What happens if a hanger bolt is reused?
It may not grip securely and could cause leaks or loosen over time—weakening both structure and waterproofing.
Q2: How to tell if a bolt needs replacement?
Replace if you find any thread damage, rust spots, or worn washers. Always swap the full assembly if defects are found.
Q3: Are any solar mounting fasteners reusable?
Yes—middle clamps and side clamps can be reused if undamaged. Bolts that penetrate roofs, however, must be replaced after removal.
5. Final Thoughts: Don’t Risk System Safety for Minor Savings
While saving on hardware may feel tempting, the potential for leaks, corrosion, and system failure means reused solar hanger bolts could be much more costly in the end. Always choose new, certified stainless steel hanger bolts for every job.
Key Takeaway
| Factor | Reuse Risk | Recommendation |
|---|---|---|
| Structural Grip | ⚠️ Reduced holding power | Use new bolts |
| Waterproofing | ⚠️ Seal failure | Replace washers/sealant |
| Safety/Compliance | ⚠️ Non-compliant | Follow manufacturer specs |
Need Reliable Solar Fasteners?
At Suzhou Bilateral Import and Export Co., Ltd., we specialize in solar mounting systems and stainless-steel fasteners — including high-quality solar hanger bolts, roof hooks, and solar accessories engineered for long-lasting performance.
Visit us at www.szbolts.com to learn more or request a custom quote for your next project.
