Application of Hanger Bolts in Roof Mounting Systems

In solar roof mounting systems, hanger bolts are one of the most widely used fasteners for metal roof installations. Designed with a combination of wood thread and machine thread, hanger bolts penetrate metal roof sheets and secure directly into wooden purlins or structural components, providing strong and reliable support for the entire solar roof mounting system.

As an essential solar fastener, hanger bolts are widely used in corrugated metal roofs, trapezoidal sheet roofs, wooden roofs, and other metal roof structures, making them a key component in modern photovoltaic installations.

What Is a Hanger Bolt?

A hanger bolt is a dual-thread fastener featuring:

• Wood thread on one end for anchoring into wood purlins

• Machine thread on the other end for attaching mounting components

A standard solar hanger bolt assembly typically includes:

• Hanger Bolt (M8 / M10)

• EPDM sealing washer

• Stainless steel nut / flange nut

• L Feet (L Bracket)

• Compatible mounting rail and clamps

Common materials:
Stainless Steel 304 (A2) / Stainless Steel 316 (A4)

Applications of Hanger Bolts in Roof Mounting Systems

1. Metal Roof / Corrugated Metal Roof Mounting

Hanger bolts are most commonly used on corrugated metal sheets and trapezoidal roofs. They penetrate the roofing material and secure directly into the underlying wooden purlins.

Features:

• Used together with L Feet

• EPDM washers ensure excellent waterproofing

• Quick installation, suitable for various roof profiles

This is currently the most widely used solar hanger bolt solution for distributed PV projects.

2. Wooden Structure Roofs

For roofs with wooden purlins, the wood-threaded side provides outstanding pull-out strength and ensures long-term system stability.

Suitable for:

• Wooden houses

• Wooden panel roofs

• Light-structure roofs with solar mounting

3. Corrugated / Asbestos Roofs

Hanger bolts can be installed in the valley of corrugated roofs and used together with L feet to create a solid mounting foundation.

Advantages:

• Eliminates the need for tile cutting

• Corrosion-resistant, ideal for long-term outdoor use

Benefits of Using Hanger Bolts

1. High Versatility

Compatible with a wide range of metal roofs, corrugated sheets, and wooden roofs, making them a universal solar fastener.

2. Easy Installation

Requires only drilling and screwing—no welding or extra structural work.

3. Excellent Corrosion Resistance

Made of SS304/SS316, offering long-lasting durability in outdoor environments.

4. Full Compatibility with Solar Mounting Components

Works perfectly with:

• L feet

• Aluminum rails

• Mid clamps

• End clamps

• Other solar mounting accessories

Common Specifications

FAQ

1. What types of roofs can hanger bolts be used on?

They are suitable for metal roofs, corrugated roofs, trapezoidal roofs, and wooden roofs, especially where penetration fixing is required.

2. Are hanger bolts waterproof?

Yes. When used with EPDM sealing washers, hanger bolts offer excellent waterproof performance and prevent roof leakage.

3. How do I choose between M8 and M10 hanger bolts?

• M8 → For light structures

• M10 → For heavy-duty solar projects requiring higher strength

4. Can hanger bolts be customized?

Yes, hanger bolts can be customized in length, diameter, thread type, and material (e.g., 180mm, 200mm, 250mm, 300mm).

5. What components do hanger bolts work with?

They are commonly used with L feet, aluminum mounting rails, mid & end clamps, nuts, and washers, forming a complete solar roof mounting system.