Legal Question in Real Estate Law in Maryland

You may have lost your right to contest this by going to settlement without first ascertaining that the seller had complied with the terms of the radon addendum. But if the seller affirmatively misrepresented that they complied, you may have a claim for fraudulent misrepresentation. However, there is the issue of damages. You stated that the company that supplied the parts inspected it, so it seems as if it was installed correctly even though done by the owner (who was obviously trying to save a few dollars). If the installation was done correctly, then you have no basis for a claim. If you're not sure about this, you can have an independent inspection done, and if it turns out that the installation was not done correctly, ascertain the cost of correctly installing the system. You can request that the seller reimburse you for this, which they will probably refuse, and then you'll have to decide if it's worth pursuing a legal action.