Concrete by nature has minimal to negligible VOCs.
Most VOCs associated with concrete are generated from the use of stains, sealers and form release agents.
- For formed concrete, use a water based form release agent, this will produce VOCs in the neighborhood of .018 mg/m3 and a VOC release rate of .003 mg/m2h.
- Compare this to standard latex paint which has a VOC rate of 2.00 mg/m3 and .43 mg/m2h release rate.
- If you are staining the concrete surfaces, look into concrete stains derived from fish oil. It is natural and provides a beautiful finish.
As for alternatives to concrete, once you introduce glues, sealers, binding agents you increase the VOC content and release into the home.
For your project, one of the biggest challenges you will face is insulating the exterior of the home if it is formed concrete without introducing insulation and possible VOCs to the interior.
- One solution to this could be the installation of a rainscreen exterior.
- Not only is it aesthetically pleasing but you can install the insulation to the exterior beneath the rainscreen facade of the building minimize thermal bridging.
For more information:
Read "Is concrete flooring eco-friendly? What's the best way to finish it-stain, paint, polish?" a Q&A answered by Brad Hubbell.
Also, read "What is the most reliable, user-friendly, low-VOC, water-based concrete stain available?" a Q&A answered by Joel Hirshberg.