A real estate seller is required under Pennsylvania law to disclose to any potential buyer known material defects in the property.
most real estate defects will not be this obvious
The Pennsylvania Association of Realtors (PAR) provides a disclosure form that goes beyond the requirements of Pennsylvania law for disclosure of defects. The basic disclosure requirements are found in the Real Estate Commission's form here at the Pennsylvania Department of State website.
If you are a buyer, you are better off using the PAR form, especially in light of the increased risk of fraud in today's real estate environment.