> For the complete documentation index, see [llms.txt](https://docs.betterbuilding.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.betterbuilding.io/support-and-training/other-support/faqs/design-and-specification/materials/framing-thermally-broken-frames.md).

# Framing - Thermally Broken Frames

A thermal break is a material of low thermal conductivity placed in an assembly to reduce or prevent the flow of thermal energy between conductive materials. Thermal breaks have traditionally been the focus of cold climates but are now deemed a good design practice in all climates where performance design is a consideration.

In the context of glazing systems, thermally broken refers to frame products with a low thermal conductivity material to avoid unwanted heat loss or gain and lower condensation risk. Market-dependent thermal breaks of PVC, neoprene rubber, polyurethane and polyester-reinforced nylon are used for improved thermal performance. A thermal break separating the external and internal framing elements is at least 5.3 mm thick. It can be up to 25 mm or more with the polyester-reinforced nylon varieties.

Classified by the U.S. National Fenestration Rating Council (ref: NFRC 100-2016), thermal breaks can be defined as:

> *‘Thermal break: a material of low thermal conductivity inserted between members of high conductivity to reduce heat transfer. Thermal barrier material conductivity shall be no more than 0.5 W/mK’.*

Where an installed thermal break does not meet the above definition, particularly in reference to its depth and ability to separate external and internal framing components, it may be defined as thermally improved. In temperate climates, such thermal improvements provide good value reductions to heat transfer and are common in curtain wall systems.<br>


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.betterbuilding.io/support-and-training/other-support/faqs/design-and-specification/materials/framing-thermally-broken-frames.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.