It really depends. Are you hoping to rent out the basement separately, or are you trying to squeeze in another bedroom?
To be a separate rental unit, it needs to have a dedicated entrance from the outside, and there needs to be an egress opening in any and all bedrooms no matter which way you're planning on doing things.
You best resource is the Borough of Collegeville or whichever municipality the property is in.
Joshua Stein, REALTORÂ®
Coldwell Banker Preferred â€“ Conshohocken
Office:(610) 828-9558 * Cell:(215) 866-8030
Direct:(484) 270-1165 * Fax: (215) 999-5894
PA License #RS317975