Before taking further and costly measures, such as adding a membrane foundation water proofing or reworking the french drain -- let's be sure water is flowing away from the home.
- Do you have positive drainage away from the home - at least 1/2" per foot? If not, adding 2" of soil 4 feet wide against the foundation and reseeding will help.
- Reconnect any loose or unsealed downspout pipes. Connect downspouts to any underground pipes (also check for pipe leaks via camera).
- Extend downspouts that discharge 12" or so from the home to 4 feet.
- Check for gutters that overflow in a heavy rain.
- Also, if you have a foundation drain, check to see that its outflow is clear.
Once the water issue is resolved www.concreteearth.com has some greener concrete floor sealing solutions that may work for you such as DRYCRETE which is a zero-VOC deep penetrating sealer.
Good luck with the investigation and reclaiming your basement.
For more information:
Read "How can I improve my outdoor area to avoid getting water in my basement and near-flooding in my backyard?" a Q&A answered by Ryan Flegal.