Thermal Bridging and Mounting 2020 Aluminum Extrusion With Rivets in Van Walls (Explanation)

Forum Post #

https://www.fordtransitusaforum.com/threads/looking-for-options-to-insulate-thermal-bridge.88445/

Explanation #

Isolating metal siding from aluminum extrusion framing in your van is advised to prevent thermal bridging, which occurs when there is a direct conductive path between the interior and exterior metal surfaces. This can lead to inefficient insulation, causing the interior to heat up or cool down rapidly with the exterior temperature. Additionally, when two different metals are in contact, there’s a risk of galvanic corrosion, which can deteriorate the metals over time. Here’s what you need to know and some methods to isolate the two metals:

Understanding the Need for Isolation #

• Thermal Bridging: This reduces the effectiveness of your van’s insulation because heat escapes or enters more easily through the metal frames, leading to an uncomfortable interior climate and higher energy costs for heating or cooling.
• Galvanic Corrosion: Different metals have different electrochemical properties. When they are in contact, especially in the presence of an electrolyte (like water), it can cause one metal to corrode faster than it would on its own.

Ways to Isolate the Two Metals #

Use Non-Conductive Barriers: #

• Place a non-conductive material, such as rubber, plastic shims, or specially designed insulation tape, between the aluminum extrusion and the van’s metal siding. This barrier prevents direct metal-to-metal contact, reducing heat/cold transfer and the risk of galvanic corrosion.

Insulation Foam or Sheets: #

• Using rigid foam insulation panels or spray foam insulation not only isolates the metals but also adds to the thermal insulation of the van. Ensure the foam is compatible with both metal types and does not promote corrosion.

Thermal Breaks: #

• Incorporate materials that act as thermal breaks within the framing structure. These are elements with low thermal conductivity placed between the aluminum framing and the metal siding. They significantly reduce thermal bridging.

Plastic or Nylon Washers and Bushings: #

• When bolting or attaching the aluminum framing to the van’s body, use plastic or nylon washers and bushings to prevent direct metal contact.

Paint or Coating: #

• Applying a protective coating or paint that prevents corrosion to the surfaces of both metals can help. Ensure the coating is durable and designed for use with the specific metals in question.

Use of Sealants: #

• Sealants and caulks that are designed to prevent moisture ingress can also be used around the interface between the two metals, further reducing the risk of galvanic corrosion by preventing water from acting as an electrolyte.

Considerations #

• Material Compatibility: Ensure that the isolation materials you choose are compatible with both the van’s siding and the aluminum extrusion to prevent chemical reactions that could lead to corrosion.
• Structural Integrity: The method of isolation should not compromise the structural integrity of your van’s modifications.
• Professional Advice: It might be beneficial to consult with a professional in van conversions or a materials specialist to choose the best isolation methods for your specific situation.

Isolating the two metals is crucial for maintaining the longevity of your van’s modifications and ensuring that the internal environment remains comfortable and energy-efficient.

Won’t there always be metal to metal contact because I have to adhere the 2020 with metal screws to the walls? #

Yes, if you directly attach 2020 aluminum extrusions to the metal walls of a van using metal screws, there will be metal-to-metal contact, which can indeed create thermal bridges. Thermal bridges allow heat and cold to pass more easily through the insulated barriers, potentially reducing the effectiveness of the insulation and leading to issues such as increased energy costs, condensation, or uncomfortable temperatures inside the van.

However, there are strategies to minimize the impact of thermal bridging while still securing the aluminum extrusions to the van walls:

1. Use Thermal Breaks: #

Insert a non-conductive material between the 2020 aluminum extrusions and the van walls. Materials such as rubber pads, plastic shims, or specifically designed insulating washers can act as thermal breaks, significantly reducing heat transfer through the screw connections.

2. Limit Metal Screw Contact: #

Whenever possible, limit the number of metal screw connections between the extrusion and the van walls. This can be achieved by using alternative fastening methods where feasible or by strategically planning where screws are absolutely necessary and minimizing their use.

3. Insulating Washers: #

When using screws, consider employing insulating washers that provide a barrier between the screw head and the aluminum extrusion. These washers can be made of rubber, nylon, or other insulating materials and help reduce thermal bridging.

4. Sealant or Foam: #

Applying a non-conductive sealant or expanding foam around the screw area can also help to minimize heat transfer. This method can be particularly effective if combined with thermal breaks or insulating washers.

5. Overall Insulation Strategy: #

Focus on the overall insulation strategy of your van. While minimizing thermal bridges is important, ensuring that the van is well-insulated as a whole (including high-quality wall, ceiling, and floor insulation) can mitigate some of the effects of thermal bridging.

6. External Cladding: #

For some builds, adding an external layer of cladding that covers the entire framework can help reduce the effects of thermal bridging by creating a continuous insulative barrier outside the metal frame.

It’s important to balance the need for structural integrity with the desire to minimize thermal bridging. While it might not be possible to eliminate all metal-to-metal contact, employing these strategies can significantly reduce heat transfer, improving the thermal performance of your van conversion. Consulting with a professional experienced in van conversions can also provide you with customized solutions tailored to your specific build and climate needs.